JP4846938B2 - Eye characteristics measuring device - Google Patents

Description

となる。また、集光点Ｐｃが角膜６２の前面に達してから後面に達するまでのレンズ部Ｐｌがｌ_Ｐｌ（＝ΣΔｌ_Ｐｌ、総移動量）移動したとき、
【００４０】
【数２】

（ｒ：角膜６２の前面の曲率半径（ステップＳ１０１において、プラチドリング７１（ケラトリングでもよい）から予め算出）
よって、
【００４１】
【数３】

となる。このとき、
【００４２】
【数４】

となり、参照ミラー１４の１次・２次干渉縞検出のための移動量ｌ_ｒｅｆと、レンズ部の角膜前面−後面間の移動量ｌ_ｐｌと、プラチドによる角膜形状測定から得られた角膜６２の前面の曲率半径ｒを代入することにより、角膜６２の屈折率ｎを得ることができる。
【００４３】
（ｖｉｉ）角膜６２の厚さ算出
次に、求められた角膜６２の屈折率ｎと、参照ミラー１４の移動量ｌ_ｒｅｆとから上式（数１）により角膜６２の厚さｔを算出する（Ｓ１１３）。
以上により、被検眼の角膜６２の屈折率、厚さを求めることができる。
また、被検眼６０の網膜６１まで照明光を導光させ、参照ミラー１４を、検出手段２７の出力が水晶体６３の前面、後面に相当する干渉縞の次の第５次干渉縞まで観測できるように移動させることによって、参照ミラー１４の移動量Ｉ_refと被検眼６０における角膜６２、房水６４、水晶体６３のそれぞれの屈折率ｎ、ｎ_１、ｎ_２から、正確な眼軸長Ｌ_ｅｙｅ ^Ｒを求めることができる。ここで、眼軸長とは、例えば角膜前面と網膜との光学的距離（屈折率×距離）をいう。この際、検出手段２７の出力は、一般的に、角膜６２の前面、後面、水晶体６３の前面、後面に相当する干渉縞の次の第５次干渉縞の振幅が最大となる。そのときの第１次干渉縞から第５次干渉縞までの距離が正確な眼軸長の大きさとなる。その大きさは、例えば略１７ｍｍ程度となる。
【００４４】
（第２の実施の形態）
図９は、第２の実施の形態に関する眼特性測定装置１５０の概略光学系を示す図である。なお、ここでの光学系は、主に、角膜の屈折率と角膜厚と眼の収差と角膜の形状の測定を行う場合について示している。なお、上述の第１の実施の形態の眼特性測定装置１００と重複する光学系に含まれる部材等については、同一符号を付し、機能、構成は同様である。
第１受光光学系２０’は、例えば、第１の実施の形態における第１受光光学系２０に対して、ハルトマン板２２を追加したものである。第１受光光学系２０’は、例えば、コリメートレンズ２１と、ハルトマン板２２と、第１受光部２３と、コリメートレンズ２１とハルトマン板２２との間に挿入された第４ビームスプリッター２５と、集光レンズ２６と、検出手段 ２７と、第１受光光学系移動手段２８とを備える。ハルトマン板２２は、被測定眼６０の網膜６１から反射して戻ってくる光束（第１光束）の一部を、少なくとも、１７本のビームに変換する変換部材である。第１受光部２３は、このハルトマン板２２で変換された複数のビームを受光するためのものである。また、ここでは、第１受光部２３は、リードアウトノイズの少ないＣＣＤが採用されているが、ＣＣＤとしては、例えば、一般的な低ノイズタイプ、測定用の１０００＊１０００素子の冷却ＣＣＤ等、適宜のタイプのものを適用することができる。
また、第１照明光学系１０’は、第１光源部１１、集光レンズ１２、レンズ１２’、クロスシリンダーレンズ１７、絞り１８、移動手段１９を備える。移動手段１９は、集光レンズ１２の移動及びクロスシリンダーレンズ１７の絞りを別個に調整することができる。さらに、第１受光部２３、ハルトマン板２２を用いた測定を行なう際に、集光光学系移動手段９１により、コリメートレンズ９２を光学系から取り除くように移動させることができる。
【００４５】
第２の実施の形態における眼特性測定装置１５０は、第１の実施の形態と同様に角膜６２の屈折率、角膜厚を算出する。その際、集光点の位置の調整は、集光光学系移動手段９１によるコリメートレンズ９２の移動のみならず、さらに、移動手段１９による第１照明光学系１０’の移動及び／又は、第１受光光学系移動手段２８による第１受光光学系２０’の移動により調整することも可能である。その後、前眼部前の集光光学系９０に含まれるコリメートレンズ９２をはずして眼の収差測定を行う。
【００４６】
つぎに、ハルトマン板を用いた眼の収差測定について、第１照明光学系１０’と第１受光光学系２０’との位置関係を概略的に説明する。
第１受光光学系２０’には、第４ビームスプリッター２５が挿入されており、この第４ビームスプリッター２５によって、被測定眼６０からの反射光は、透過され、第１受光光学系２０に含まれる第１受光部２３は、変換部材であるハルトマン板２２を通過した光を受光し、受光信号を生成する。
【００４７】
また、第１光源部１１と被測定眼６０の網膜６１とは、共役な関係を形成している。被測定眼６０の網膜６１と第１受光部２３とは、共役である。また、ハルトマン板２２と被測定眼６０の瞳孔と絞り１８とは、共役な関係を形成している。さらに、第１受光光学系２０は、被測定眼６０の前眼部である角膜６２、及び瞳孔と、ハルトマン板２２と略共役な関係を形成している。すなわち、アフォーカルレンズ４２の前側焦点は、被測定眼６０の前眼部である角膜６２及び瞳孔と略一致している。
【００４８】
また、第１照明光学系１０’と第１受光光学系２０’は、第１光源部１１からの光束が、集光する点で反射されたとして、第１受光部２３での反射光による信号ピークが最大となるように、連動して移動する。具体的には、第１照明光学系１０’と第１受光光学系２０’は、それぞれ移動手段１９及び第１受光光学系移動手段２８により、第１受光部２３での信号ピークが大きくなる方向に移動し、信号ピークが最大となる位置で停止する。これにより、第１光源部１１からの光束は、被測定眼６０の網膜６１上で集光する。このとき、移動手段１９は、さらに、絞り１８の絞りも調整可能としてもよい。このように、移動手段１９及び第１受光光学系移動手段２８は、屈折率・角膜厚の測定と、収差測定に兼用されることができる。
【００４９】
また、集光レンズ１２は、第１光源部１１の拡散光を平行光に変換する。集光レンズ１２の近傍に配された絞り１８は、眼の瞳、あるいはハルトマン板２２と光学的に共役の位置にある。絞り１８は、径がハルトマン板２２の有効範囲より小さく、いわゆるシングルパスの収差計測（受光側だけに目の収差が影響する方法）が成り立つ様になっている。集光レンズは、上記を満たすために、実光線の眼底共役点を前側焦点位置に、さらに、眼の瞳との共役関係を満たすために、後側焦点位置が絞りと一致するように配置されている。
【００５０】
また、光線１５’は、光線２４と第１ビームスプリッター４１で共通光路になった後は、近軸的には、光線２４と同じ進み方をする。但し、シングルパス測定のときは、それぞれの光線の径は違い、光線１５’のビーム径は、光線２４に比べ、かなり細く設定される。具体的には、光線１５のビーム径は、例えば、レーザ光線が眼の瞳に入射するとき、眼の瞳位置で１ｍｍ程度になり、網膜６１からの拡散反射光が眼の瞳から出射するとき、眼の瞳位置で７ｍｍ程度になることもある（なお、図中、光線１５’の第１光源部１１からの光束における第１ビームスプリッター４１から眼底までは省略している）。
【００５１】
つぎに、変換部材であるハルトマン板２２について説明する。
第１受光光学系２０に含まれるハルトマン板２２は、反射光束を複数のビームに変換する波面変換部材である。ここでは、ハルトマン板２２には、光軸と直交する面内に配された複数のマイクロフレネルレンズが適用されている。また、一般に、測定対象部（被測定眼６０）について、被測定眼６０の球面部分、３次の非点収差、その他の高次収差までも測定するには、被測定眼６０を介した少なくとも１７本のビームで測定する必要がある。
【００５２】
また、マイクロフレネルレンズは、光学素子であって、例えば、波長ごとの高さピッチの輪帯と、集光点と平行な出射に最適化されたブレーズとを備える。ここでのマイクロフレネルレンズは、例えば、半導体微細加工技術を応用した８レベルの光路長差を施したもので、高い集光率（例えば、９８％）を達成している。また、被測定眼６０の網膜６１からの反射光は、コリメートレンズ９２、アフォーカルレンズ４２を通過し、ハルトマン板２２を介して、第１受光部２３上に集光する。したがって、ハルトマン板２２は、反射光束を少なくとも１７本以上のビームに変換する波面変換部材を備える。
【００５３】
図１０は、第２の実施の形態に関する眼光学特性測定装置１５０の概略電気系３００を示すブロック図である。眼光学特性測定装置１５０に関する電気系３００は、例えば、演算部３１０と、制御部３２０と、表示部３３０と、メモリ３４０と、第１駆動部３５０と、第２駆動部３６０と、第３駆動部３７０と、第４駆動部３８０とを備える。
【００５４】
演算部３１０は、第１受光部２３から得られる受光信号▲４▼、第２受光部８２から得られる受光信号▲８▼、第３受光部５４から得られる受光信号(11)、検出手段２７から得られる受光信号(12)を入力すると共に、座標原点、座標軸、座標の移動、回転、全波面収差、角膜６２の面収差、ゼルニケ係数、収差係数、Ｓｔｒｅｈｌ比、白色光ＭＴＦ、ランドルト環パターン等を演算する。また、演算部３１０は、このような演算結果に応じた信号を、電気駆動系の全体の制御を行う制御部３２０と、表示部３３０と、メモリ３４０とにそれぞれ出力する。なお、演算３１０の処理の詳細は後述する。
【００５５】
制御部３２０は、演算部３１０からの制御信号に基づいて、第１駆動部３５０、第２駆動部３６０、第３駆動部３７０及び第４駆動部３８０を制御するものである。制御部３２０は、例えば、演算部３１０での演算結果に応じた信号に基づいて、第１光源部１１に対して信号▲１▼を出力し、第２光源部３１に対して信号▲７▼を出力し、第４光源部５５に対して信号(10)を出力し、第３光源部５１に対して信号▲９▼を出力する。さらに、制御部３２０は、第３駆動部３７０を介して信号▲２▼を移動手段１９に出力し、第４駆動部３８０を介して信号▲３▼を第１受光光学系２０を駆動する第１受光光学系移動手段２８に出力し、さらに、第１駆動部３５０を介して信号▲５▼を集光光学系移動手段９１に出力し、第２駆動部３６０を介して信号▲６▼を参考ミラー移動手段１６に出力する。
図１１は、第２の実施の形態に関する眼特性測定装置１５０のフローチャートである。
【００５６】
（ｉ）プラチドリング７１による角膜形状測定（Ｓ１０１）、（ｉｉ）集光点の移動（Ｓ１０３）、（ｉｉｉ）集光光学系９０の移動（Ｓ１０５）、（ｉｖ）ミラーの走査（Ｓ１０７）、（ｖ）干渉縞の極大値（Ｓ１０９）、（ｖｉ）屈折率の算出（Ｓ１１１）、（ｖｉｉ）角膜６２の厚さ算出（Ｓ１１３）については、第１の実施の形態と同様である。
【００５７】
（ｖｉｉ’）眼の収差測定
ハルトマン板２２を用いた検出結果に基づき、演算部３１０は、周知の方法により、手術前の眼の収差を測定する（Ｓ２１３）。これにより、被検眼の屈折力の評価を行うことができる。
【００５８】
（ｖｉｉｉ）角膜６２の水分含有量算出
つぎに、演算部３１０は、求められた角膜６２の屈折率ｎから角膜６２の水分含有量を算出する（Ｓ２１５）。具体的には、角膜６２を水分と角膜構成物質（細胞）に分けて考え、水の屈折率を１．０、水分含有量を角膜６２に対してｘ（％）とすると、
（角膜構成物質含有量＋ｘ（水分含有量））：１００＝ｎ：１．０
この関係から、水分含有量が角膜全体に対して何％であるか算出することができる。
【００５９】
（ｉｘ）１パルスあたりの角膜６２の削り量算出
角膜６２の水分含有量から１パルスあたりの角膜６２の削り量を算出する（Ｓ２１７）。すなわち、具体的には、１パルスあたりの水分蒸発量はエキシマレーザの場合、装置により、予め定められた深さ（例えば、０．４〜０．７μｍ）で削り取られるので、ステップＳ２１５で求められた水分含有量に対して１パルスで蒸発する角膜６２の深さが求められ、それに応じて角膜６２の削り取られる量が分かる。
【００６０】
（ｘ）屈折矯正手術
求められた角膜６２の水分含有量に応じて角膜６２の屈折矯正手術が行なわれる（Ｓ２１９）。なお、角膜厚を測定しながら、屈折矯正手術を平行して行うこともできる。
【００６１】
（ｘｉ）屈折率の算出
ステップＳ２１９で行われた屈折矯正手術の後、再び、上述と同様にして再度屈折率を算出する（Ｓ２２１）。詳細については、上述のステップＳ１０１〜Ｓ１１１の処理と同様であるので、ここでは省略する。
【００６２】
（ｘｉｉ）角膜６２の厚さ算出
屈折矯正手術後、上述と同様にして（Ｓ１１３参照）、再度角膜６２の厚さを求める（Ｓ２２３）。これにより、適正に手術がおこなわれたのかどうか確認する。
【００６３】
（ｘｉｉｉ）眼の収差測定
ハルトマン板２２及び／又はプラチドリング７１を用いた検出結果に基づき、演算部３１０は、周知の方法により、手術後の眼の収差（角膜収差）を測定する（Ｓ２２５）。これにより、被検眼の屈折力の評価を行うことができる。
なお、ステップＳ２２１での屈折率の算出を省略してもよい。
【００６４】
（第３の実施の形態）
図１２は、第３の実施の形態に関する眼特性測定装置１７０の概略光学系を示す図である。なお、ここでの概略光学系は、主に、角膜の厚さと眼の収差の測定を、ズームレンズを用いて行う場合について示している。なお、上述の眼特性測定装置１００と重複する光学系に含まれる部材等については、同一符号を付し、機能、構成は同様である。
ここでの眼特性測定装置１７０は、例えば、ズームレンズ光学系９０’を備える。このズームレンズ光学系９０’により、第２の実施の形態における眼特性測定装置１５０の集光光学系９０を取り外し可能にする代わりに、光学系を調整するものである。なお、図３の概略図は、第３の実施の形態における眼特性測定装置１７０に対応している。
また、電気系のブロック図は、第２の実施の形態と同様であるが、ズームレンズ光学系９０’の制御が異なる。すなわち、ズームレンズ光学系９０’は、コリメートレンズ９２と、ズームレンズ９３とを含み、図１２の信号▲５▼が第５駆動部４９０を介してズームレンズ移動手段９４を移動し、コリメートレンズ９２及びズームレンズ９３の間隔である面間隔を変えることにより、集光点を角膜６２上に集光させたり、平行光入射させて収差測定を行ったりできるようにする。よって、第１・２の実施の形態のように集光光学系９０を取り外すことなく、角膜６２の屈折率、角膜厚、及び、眼の収差等を測定することができる。また、眼特性測定のフローチャートは、第２の実施の形態と同様である。
【００６５】
なお、角膜６２の中心部以外の周辺部をも測定して、角膜全体の形状マップをつくるために、上述の眼特性測定装置１００、１５０、１７０の第２照明光学系７０及び調整用光学系５０を、被検眼６０のアライメントを調整しながら移動可能にする走査手段をさらに備えることにより、角膜厚は瞳（一部または）全面をスキャンして測定することもできる。こうすることで、角膜厚の全部または一部を一度に測定し、角膜全体の形状をマップにして把握することができる。
【００６６】
（第４の実施の形態）
角膜厚を測定するときと同様に、第１の実施の形態、図５、図６、図７に示すように演算部、検出手段２７により検出された干渉縞から、屈折率の変化する境界面（房水−水晶体、水晶体−硝子体、硝子体−網膜）を検出し、水晶体６３、被検眼（硝子体）６０の屈折率ｎ_１、ｎ_０を算出し、眼軸長Ｌ_ｅｙｅ ^Ｒを算出する。
算出された眼軸長Ｌ_ｅｙｅ ^Ｒをもとにして、被検眼の軸上のパワーを算出し、被検眼６０の収差マップからパワーマップを出力する。
ここでは、対象とする波面の位置をＸ，Ｙで表示するものとし、光軸を含む断面において、その位置での波面の法線が光軸と交わる点と、その時に光軸上での波面の位置までの距離をＬｐとする。このときのパワーＰを１／Ｌｐ＋１／Ｌ_ｅｙｅ ^Ｒとする。ここで、Ｌ_ｅｙｅ ^Ｒは、上述したように正確に測定された眼の眼軸長を表わす。また、波面の各位置（ｒ，ｔ）でのパワー分布をＰ（ｒ，ｔ）で表わす。このパワー分布Ｐ（ｒ，ｔ）は、眼の屈折力分布（Ｏｃｕｌａｒ Ｒｅｆｒａｃｔｉｖｅ Ｐｏｗｅｒ Ｍａｐ）に相当する。
【００６７】
つぎに、Power Map計算方法について説明する。
まず、求められた波面収差Ｗ（Ｘ，Ｙ）をパワー表示に変換する場合について説明する。なお、このパワー表示は、主に後述する第１〜５表示例において示される。
ここでは、対象とする波面の位置をＸ，Ｙで表示するものとし、光軸を含む断面において、その位置での波面の法線が光軸と交わる点と、その時に光軸上での波面の位置までの距離をL_Pとする。
このときのパワーＰを１／Ｌ_Ｐ＋１／Ｌ_ｅｙｅ ^Ｒとする。ここで、Ｌ_ｅｙｅ ^Ｒは、正確に測定された眼の眼軸長である。
従来、一般的な眼軸長を１７ｍｍと推定し、被検眼の軸上のパワーを算出し、被検眼６０の収差マップからパワーマップを出力していたが、本実施の形態により、正確な眼軸長を算出し、被検眼の軸上のパワーを算出し、被検眼６０の収差マップからパワーマップを出力することができる。
【００６８】
【発明の効果】
本発明によると、以上説明した通り、従来の眼特性測定装置に低コヒーレント干渉を用いた角膜の形状や厚さ、屈折率測定の機能を付加し、さらに被検眼眼球の収差、手術後の角膜形状等を求め、屈折矯正手術での角膜の削り量の算出を行うことができるので、角膜矯正手術において角膜の正確な手術を行うことができる。
【図面の簡単な説明】
【図１】本発明に関する眼特性測定装置１００の概略光学系を示す図。
【図２】プラチドリング７１の構成図。
【図３】本発明に関する眼特性測定装置１００の概略電気系２００を示すブロック図。
【図４】第１の実施の形態に関する眼特性測定装置１００のフローチャート。
【図５】参照ミラー１４の移動距離と検出手段２７との関係を示す図（１）。
【図６】参照ミラー１４の移動距離と検出手段 ２７との関係を示す図（２）。
【図７】参照ミラー１４の移動距離と検出手段 ２７との関係を示す図（３）。
【図８】角膜６２の屈折率算出の方法を説明するための概略図。
【図９】本発明に関する眼特性測定装置１５０の概略光学系を示す図。
【図１０】本発明に関する眼光学特性測定装置１５０の概略電気系３００を示すブロック図。
【図１１】本発明に関する眼特性測定装置１５０のフローチャート。
【図１２】本発明に関する眼特性測定装置１７０の概略光学系を示す図。
【符号の説明】
１０ 第1照明光学系
１４ 参照ミラー
２０ 第1受光光学系
２２ ハルトマン板
３０ 第２送光光学系
４０ 共通光学系
４１ 光路分割光学系（第１ビームスプリッター）
５０ 調整用光学系
６０ 被測定眼
６１ 網膜
６２ 角膜
７０ 第２照明光学系
７１ プラチドリング
８０ 第２受光光学系
９０ 集光光学系
１００、１５０、１７０ 眼特性測定装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eye characteristic measuring device that measures optical characteristics of an eye to be examined.
[0002]
[Prior art]
In recent years, optical instruments used for medical purposes have spread very widely. In particular, in the ophthalmology, this optical apparatus is treated as an optical characteristic measuring apparatus that performs eye functions such as eye refraction and adjustment, and inspection in the eyeball.
[0003]
In general, corneal topography includes many predictions such as corneal incision and corneal cutting, clinical practice after corneal transplantation, design and evaluation of contact lenses for myopia and hyperopia, corneal diagnosis and disease determination, etc. It is effective for use. Conventional corneal shape measuring methods include, for example, Prade disk technology, stereoscopic photography technology, moire technology, topography interference technology, and the like.
[0004]
As this eye characteristic measuring apparatus, for example, a point light source is projected onto the fundus, diffuse reflected light from the eye light passes through the eyeball optical system, and the light flux that has passed through is converted into a predetermined number of beams by a conversion member such as a Hartmann plate. Devices that convert and receive this beam at a light receiving unit to measure optical characteristics of the eye, and a corneal shape measuring device that measures a corneal shape using a platid ring by near infrared light are known.
[0005]
[Problems to be solved by the invention]
However, with such a conventional ophthalmic characteristic measuring device, the corneal thickness and the refractive index of the cornea are accurately determined when determining the amount of corneal shaving in refractive surgery and when evaluating the optical characteristics of the eye after surgery. It was necessary to ask for. However, it is necessary to measure corneal thickness using another device, and the commonly used value is used for the refractive index of the cornea, and there is a need to obtain a value for each eye. It came out.
[0006]
In view of the above points, an object of the present invention is to provide an eye characteristic measuring device in which a function of measuring the shape and thickness of a cornea and refractive index using low coherent interference is added to the eye characteristic measuring device. In addition, the present invention provides an eye characteristic measuring device capable of performing more accurate surgery by calculating aberrations of the eye to be examined, corneal shape after surgery, etc., calculating the amount of corneal shaving in refractive surgery. The purpose is to do.
[0007]
[Means for Solving the Problems]
  According to the first solution of the present invention,
  A first light source that emits a light beam having a wavelength in the near infrared region;
  An optical path dividing means for guiding a part of the light beam emitted from the first light source part to the anterior eye part to be examined and taking out a part of the light beam as reference light;
  Condensing means for condensing the light beam from the first light source unit on the anterior eye portion to be examined;
  Reflecting means for reflecting the reference light from the optical path dividing means;
  Interference formed through the optical path dividing means by the reflected light from the anterior segment of the eye to be examined and the reference light reflected by the reflecting meansStreaksDetecting means for detecting
  First moving means for moving a condensing point in the vicinity of the anterior eye part of the eye to be examined, in which the light flux from the first light source part is collected by the condensing means;
  Second moving means for moving the reflecting means in the optical axis direction;
  The first moving means controls the movement of the condensing point at the anterior eye portion of the eye to be examined, and the second moving means controls the movement of the reflecting means while the interference by the detecting means.StreaksCalculation unit to determine the corneal refractive index or corneal thickness of the eye
With,
The calculation unit calculates an corneal refractive index and / or a corneal thickness based on the calculated curvature radius of the front surface of the cornea and a moving distance by the first and second moving means.I will provide a.
According to the second solution of the present invention,
A first light source that emits a light beam having a wavelength in the near infrared region;
An optical path dividing means for guiding a part of the light beam emitted from the first light source part to the anterior eye part to be examined and taking out a part of the light beam as reference light;
Condensing means for condensing the light beam from the first light source unit on the anterior eye portion to be examined;
Reflecting means for reflecting the reference light from the optical path dividing means;
Detecting means for detecting interference fringes formed through the optical path dividing means from the reflected light from the anterior segment of the eye to be examined and the reference light reflected by the reflecting means;
First moving means for moving a condensing point in the vicinity of the anterior eye part of the eye to be examined, in which the light flux from the first light source part is collected by the condensing means;
Second moving means for moving the reflecting means in the optical axis direction;
The cornea of the eye to be inspected based on the detection result of the interference fringes by the detecting means while the movement of the condensing point at the anterior eye part of the eye to be examined is controlled by the first moving means and the reflecting means is moved by the second moving means. Calculation unit for obtaining refractive index or corneal thickness
With
The calculation unit provides an eye characteristic measurement device that controls the first moving unit to remove the condensing unit from the optical system and measures the aberration of the eye to be examined.
[0008]
  First of the present invention3According to the solution of
  A first light source that emits a light beam having a wavelength in the near infrared region;
  An optical path dividing means for guiding a part of the light beam emitted from the first light source part to the anterior eye part or the retina to be examined and taking out a part of the light beam as reference light;
  Condensing means for condensing the luminous flux from the first light source part on the anterior eye part or the retina to be examined;
  Reflecting means for reflecting the reference light from the optical path dividing means;
  Interference formed through the optical path dividing means from the reflected light from the anterior eye part or retina of the eye to be examined and the reference light reflected by the reflecting meansStreaksDetecting means for detecting
  First conversion means for converting a part of the first reflected light beam reflected from the retina of the eye to be examined into at least substantially 17 beams, the first light beam from the first light source unit;
  First light receiving means for receiving a beam via the conversion means;
  First moving means for moving a condensing point in the vicinity of the anterior eye part of the eye to be examined, in which the light flux from the first light source part is collected by the condensing means;
  Second moving means for moving the reflecting means in the optical axis direction;
  The first moving means controls the movement of the condensing point at the anterior segment of the eye to be examined, and the second moving means controls the movement of the reflecting means, while the interference by the detecting means.StreaksA calculation unit that obtains the corneal refractive index or the corneal thickness of the eye to be examined from the detection result of the eye, and obtains the aberration of the eye to be examined by the reflected light from the eye retina detected by the first light receiving means
An eye characteristic measuring apparatus comprising:
[0009]
As one of the features of the present invention, a second light source unit for illuminating the anterior ocular segment to be examined, a second detection unit for detecting reflected light from the anterior ocular segment to be examined, and detection from the second detecting unit An arithmetic unit for obtaining corneal aberration of the eye to be examined can be provided from the result.
[0010]
As another feature of the present invention, the corneal refractive index or corneal thickness obtained can be compared with a corneal refractive index or corneal thickness that is normally calculated, and an arithmetic unit that calculates the shaving amount of the corneal shaving can be provided. .
[0011]
As another feature of the present invention, it is possible to provide an arithmetic unit for calculating the ocular aberration distribution from the corneal aberration of the subject eye by obtaining the axial length of the subject eye or the power on the pupil central axis of the subject eye. .
[0012]
As another feature of the present invention, it is possible to provide an arithmetic unit for obtaining the axial length of the eye to be examined or the power on the pupil central axis of the eye to be examined and calculating the eye aberration distribution from the corneal aberration of the eye to be examined.
[0013]
As another feature of the present invention, the condensing optical system is a zoom lens optical system, and the corneal refractive index or corneal thickness of the eye to be examined is obtained, and the aberration of the eye to be examined is obtained by reflected light from the retina of the eye to be examined. Also good.
[0014]
As another feature of the present invention, a second illumination optical system for illuminating the periphery of the anterior segment of the eye to be examined is provided, the radius of curvature of the front surface of the cornea of the eye to be examined is obtained, and the subject is measured from the moving distance and the radius of curvature of the second moving means. You may make it have a calculating part which calculates | requires the corneal refractive index or corneal thickness of an optometry.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a schematic optical system of an eye characteristic measuring apparatus 100 according to the first embodiment. The optical system here mainly shows the case of measuring the corneal shape, the refractive index, and the corneal thickness.
[0016]
The optical system of the eye characteristic measuring device 100 is, for example, a device that measures optical characteristics of the eye 60 to be measured, which is an object, with respect to the cornea 62, and includes a first illumination optical system 10, a reference optical system 15, and a first optical system. Light receiving optical system 20, second light transmitting optical system 30, common optical system 40, adjustment optical system 50, second illumination optical system 70, second light receiving optical system 80, and condensing optical system 90 . For the eye 60 to be measured, a cornea 62, an intraocular lens 63, and a retina 61 are shown in the figure.
[0017]
The 1st illumination optical system 10 is provided with the 1st light source part 11 for emitting the light beam of a 1st wavelength, and the condensing lenses 12 and 13, for example. The first illumination optical system 10 is for illuminating a minute region on the anterior eye part (cornea) 62 of the eye 60 to be measured with the light flux from the first light source part 11 so that the illumination conditions can be appropriately set. It is. Here, as an example, the first wavelength of the illumination light beam emitted from the first light source unit 11 is an infrared wavelength (for example, 780 nm). The first light source unit 11 preferably has a large spatial coherence and a small temporal coherence. Here, the 1st light source part 11 is a super luminescence diode (SLD), for example, Comprising: It can obtain a point light source with high brightness | luminance. In addition, the 1st light source part 11 is not restricted to SLD, For example, lasers, such as broadband LD, may be sufficient.
[0018]
The reference optical system 15 includes a reflection mirror (reference mirror) 14 and a reference mirror moving unit 16.
The first light receiving optical system 20 includes, for example, a condenser lens 21, a condenser lens 26, and a detection unit 27. The first light receiving optical system 20 includes a light beam (first light beam) reflected and returned from the anterior eye part (or cornea) 62 of the eye 60 to be measured, and an optical link (second light beam) reflected by the reference mirror 14. ) Is received by the detecting means 27 via the condenser lens 21 and the collimating lens 26. Here, the detection means 27 employs a CCD with low lead-out noise. However, as the CCD, for example, a general low noise type, a cooling CCD of 1000 * 1000 elements for measurement, etc. A type of thing can be applied.
[0019]
The second light transmission optical system 30 mainly performs, for example, alignment adjustment, coordinate origin, and measurement / adjustment of coordinate axes, which will be described later, and a second light source unit 31 for emitting a light beam of the second wavelength, An optical lens 32 and a third beam splitter 33 are provided.
[0020]
  The common optical system 40 is disposed on the optical axis of the light beam emitted from the first illumination optical system 10, and the first illumination optical system 10, the second illumination optical system 70, the first light receiving optical system 20, and the second light receiving optical system. 80, the second light transmission optical system 30 and the like. The common optical system 40 includes, for example, a first beam splitter 41, an afocal lens 42, and a second beam splitter 43. As the first beam splitter, for example, a half mirror, a deflection beam splitter, or the like is used. When a deflecting beam splitter is used, it is necessary to arrange the λ / 4 plates 44 and 45 on the branched optical path and to arrange the 45 ° polarizer 29 on the optical path where the branched optical paths merge. The first beam splitter receives the light beam having the wavelength of the first light source unit 11, transmits (reflects) a part of the light beam to the anterior eye unit 62, and reflects the first light beam reflected by the anterior eye unit 62 and returning. The second light beam that is transmitted and transmitted through the other part toward the reference optical system 15 is reflected by the reference mirror 14 and returned. As a result, interference light between the first light flux and the second light flux (Streaks) Is formed. In addition, the second beam splitter 43 transmits (reflects) the wavelength of the second light source unit 31 to the eye 60 to be measured, reflects the light flux reflected and returned from the anterior eye part 62 of the eye 60 to be measured, On the other hand, it is formed of a mirror (for example, a dichroic mirror) that transmits the wavelength of the first light source unit 11. The second beam splitter 43 prevents the light beams of the first light source unit 11 and the second light source unit 31 from entering the other optical system and causing noise.
[0021]
The adjustment optical system 50 mainly performs, for example, adjustment of a working distance described later, and includes a third light source unit 51, a fourth light source unit 55, condensing lenses 52 and 53, and a third light receiving unit 54. And mainly adjust the working distance.
[0022]
The second illumination optical system 70 includes a second light source 72 and a placido ring 71. Note that the second light source 72 may be omitted.
FIG. 2 is a configuration diagram of the placido ring 71.
The Placido ring (PLACIDO'S DISC) 71 is for projecting a pattern index composed of a plurality of concentric annular zones as shown in the figure. Note that the index of a pattern composed of a plurality of concentric annular zones is an example of an index of a predetermined pattern, and other appropriate patterns can be used. And after the alignment adjustment mentioned later is completed, the parameter | index of the pattern which consists of a some concentric ring zone can be projected.
[0023]
The second light receiving optical system 80 includes a condenser lens 81 and a second light receiving unit 82. The second light receiving optical system 80 converts the pattern of the placido ring 71 illuminated from the second illumination optical system 70 from the anterior eye part (or cornea) 62 of the eye 60 to be measured and returns the second luminous flux. The light is guided to the light receiving unit 82. Further, the second light receiving optical system 80 can also guide the returned light beam emitted from the second light source unit 31 and reflected from the cornea 62 of the eye 60 to be measured to the second light receiving unit 82. The second wavelength of the light beam emitted from the second light source unit 31 is different from, for example, the first wavelength (here, 780 nm), and a long wavelength can be selected (for example, 940 nm).
The condensing optical system 90 includes a collimating lens 92 and condensing optical system moving means 91 that moves the collimating lens 92.
[0024]
In such a configuration, the light beam emitted from the first light source unit 11 is transmitted through the optical path splitting optical system 41 (for example, the first beam splitter), extracted as reference light, and moved in the optical axis direction by the reference mirror moving means 16. The light is reflected by a possible reflection mirror (reference mirror) 14, reflected again by the optical path dividing optical system 41, and received by the first light receiving optical system 20 as a second light flux. On the other hand, the light beam reflected by the optical path splitting optical system 41 is collected by a collimator lens 92 that can be moved by the condensing optical system moving means 91 of the condensing optical system 90, and the anterior eye portion (cornea) 62 of the eye to be examined. The reflected light (first light flux) is collected on the first beam splitter 41 and received by the first light receiving optical system 20.
[0025]
Next, alignment adjustment will be described. The alignment adjustment is mainly performed by the second light receiving optical system 80 and the second light transmitting optical system 30.
[0026]
First, the light beam from the second light source unit 31 passes through the condenser lens 32, the third beam splitter 33, the second beam splitter 43, and the afocal lens 42, and is approximately parallel to the eye 60 to be measured. Illuminate with. The reflected light beam reflected by the cornea 62 of the eye 60 to be measured is emitted as a divergent light beam as if it was emitted from a point having a radius of curvature of the cornea 62. The divergent light beam is received as a spot image by the second light receiving unit 82 via the afocal lens 42, the second beam splitter 43, the third beam splitter 33, and the condenser lens 81.
[0027]
Here, when the spot image on the second light receiving unit 82 is off the optical axis, the main body of the eye optical characteristic measuring apparatus 100 is moved up and down and adjusted so that the spot image coincides with the optical axis. To do. As described above, when the spot image coincides with the optical axis, the alignment adjustment is completed. In the alignment adjustment, the cornea 62 of the eye 60 to be measured is illuminated by the third light source unit 51, and an image of the eye 60 to be measured obtained by this illumination is formed on the second light receiving unit 82. May be used so that the pupil center coincides with the optical axis.
[0028]
Next, the working distance adjustment will be described. The working distance adjustment is mainly performed by the adjustment optical system 50.
First, the working distance adjustment is performed, for example, by irradiating a parallel light beam near the optical axis emitted from the fourth light source unit 55 toward the eye 60 to be measured and the light reflected from the eye 60 to be measured. This is performed by receiving light at the third light receiving unit 54 via the condenser lenses 52 and 53. Further, when the eye 60 to be measured is at an appropriate working distance, a spot image from the fourth light source unit 55 is formed on the optical axis of the third light receiving unit 54. On the other hand, when the eye 60 to be measured deviates back and forth from an appropriate working distance, the spot image from the fourth light source unit 55 is formed above or below the optical axis of the third light receiving unit 54. Note that the third light receiving unit 54 only needs to be able to detect a change in the position of the light beam in the plane including the fourth light source unit 55, the optical axis, and the third light receiving unit 54. For example, the one-dimensionally arranged in this plane A CCD, a position sensing device (PSD), etc. can be applied.
[0029]
Next, the electrical system of the eye characteristic measuring device will be described.
FIG. 3 is a block diagram showing a schematic electrical system 200 of the eye characteristic measuring apparatus 100 according to the present invention. The electrical system 200 related to the eye characteristic measuring apparatus 100 includes, for example, a calculation unit 210, a control unit 220, a display unit 230, a memory 240, a first drive unit 250, and a second drive unit 260.
[0030]
The calculation unit 210 receives the light reception signal (10) obtained from the first light receiving unit 27, the light reception signal (2) obtained from the second light receiving unit 82, and the light reception signal (5) obtained from the third light receiving unit. The coordinate origin, coordinate axis, coordinate movement, rotation, total wavefront aberration, surface aberration of the cornea 62, Zernike coefficient, aberration coefficient, Streh ratio, white light MTF, Landolt ring pattern, and the like are calculated. In addition, the calculation unit 210 outputs signals according to such calculation results to the control unit 220 that controls the entire electric drive system, the display unit 230, and the memory 240, respectively. Details of the processing of the calculation 210 will be described later.
[0031]
The control unit 220 controls, for example, lighting and extinguishing of the first light source unit 11 and controls the first driving unit 250 and the second driving unit 260 based on the control signal from the calculation unit 210. In this example, the control unit 220 outputs a signal (7) to the first light source unit 11 on the basis of a signal according to the calculation result in the calculation unit 210, and the second light source 72 of the platide ring 71. The signal (6) is output, the signal (1) is output to the second light source unit 31, the signal (3) is output to the third light source unit 51, and the signal to the fourth light source unit 55 is output. Output (4). Further, the control unit 220 outputs the signal (8) to the condensing optical system moving unit 91 via the first driving unit 250 and the signal (9) to the reference mirror moving unit 16 via the second driving unit 260. Output.
[0032]
For example, the first driving unit 250 outputs a signal (8) to the condensing optical system moving unit 91 based on the light reception signal (10) from the first light receiving unit 23 input to the calculation unit 210. The condensing optical system moving means 91 can be driven to move the condensing point on the anterior eye part collected by the condensing optical system 90 in the optical axis direction. For example, the second driving unit 260 outputs a signal {circle over (9)} to the reference mirror moving unit 16 based on the light reception signal (10) (the circled number in the figure) from the first light receiving unit 23 input to the calculation unit 210. The reference mirror moving means 16 is driven, and the reflection mirror (reference mirror) 14 can be moved in the optical axis direction.
[0033]
FIG. 4 is a flowchart of the eye characteristic measuring apparatus 100 according to the first embodiment.
(I) Measurement of corneal shape by platide ring 71
First, the anterior eye part of the eye to be examined is illuminated by the placido ring 71 and the second light source 72, which are the second illumination optical system 70, and the curvature radius of the eye to be examined is obtained from the reflected light from the anterior eye part of the eye to be examined. (S101). At this time, the platid ring 71 may be a kerat ring, and only the radius of curvature may be obtained.
(Ii) Moving the focal point
Next, the illumination light from the first light source unit 11 of the first illumination optical system 10 is reflected and reflected by an optical path splitting optical system (hereinafter referred to as a first beam splitter) 41 to illuminate the anterior segment of the eye to be examined. (S103). On the other hand, a part of the illumination light from the first light source unit 11 is extracted through the first beam splitter 41 and reflected through the reflection mirror (reference mirror) 14 as reference light. At this time, the first drive unit 250 causes the focusing optical system 90 to focus the light beam slightly closer to the measurement device than the front surface of the cornea.
[0034]
(Iii) Movement of the condensing optical system 90
  The first driving unit 250 moves the condensing lens 92 of the condensing optical system 90 by the condensing optical system moving unit 91 (for example, about 20 μm at a time), thereby setting the condensing point of the anterior eye portion to be examined. Move (S105).
(Iv) Mirror scanning
  An interference state (interference fringes) is formed through the first beam splitter 41 by the reflected light from the vicinity of the cornea 62 (anterior eye part of the eye to be examined) and the reference light reflected by the reflecting mirror 14. This interference state (interferenceStreaks), The second drive unit 260 moves (scans) the reflecting mirror 14 by the reference mirror moving unit 16 (S107). Output data of the detection means 27 at each scanning position is appropriately stored in the memory 240 by the arithmetic unit 210.
[0035]
  Here, the moving distance of the reference mirror 14 and the detection means
27 will be described for each condensing point.
  5, 6, and 7 are views (1), (2), and (3) showing the relationship between the moving distance of the reference mirror 14 and the detection means 27.
  As shown in FIGS. 5, 6, and 7, the horizontal axis represents the moving distance (μm) of the reflecting mirror (reference mirror) 14, and the vertical axis represents the output (V) of the detection means 27 in the first light receiving optical system 20. An interference state between the reflected light from the anterior eye portion to be examined and the reference light is detected. Here, as the focal point position, FIG. 5 shows the front surface of the cornea, FIG. 6 shows the front and back surfaces of the cornea, and FIG. 7 shows the back surface of the cornea. When the reference mirror 14 is moved at the position of each condensing point, the detection output becomes as shown in the figure. The right figure in each figure shows, as an example, the signal on the left with a large detection output is the primary interference.StreaksThe next largest signal on the right is secondary interferenceStreaksIt corresponds to.
[0036]
(V) Maximum value of interference fringes
  The point where the amplitude of the envelope of the interference fringe becomes maximum when the condensing point matches the boundary surface (for example, air-cornea 62, cornea 62-aqueous humor) where the refractive index changes can be detected, and this maximum is obtained. The maximum value at the point is detected (S109). On the front side of the cornea, as shown in FIG.StreaksAre compared to obtain a position where the amplitude becomes maximum or maximum. On the other hand, on the back surface of the cornea, as shown in FIG.StreaksAre compared to obtain a position where the amplitude becomes maximum or maximum.
[0037]
(Vi) Calculation of refractive index
Two signal light intervals l obtained at this time_refThe refractive index is calculated from At the same time, the corneal shape is measured with platide, and the corneal aberration is calculated (S111).
[0038]
  Hereinafter, a method for calculating the refractive index of the cornea 62 from the signal interval will be described in detail.
  FIG. 8 is a schematic diagram for explaining a method for calculating the refractive index of the cornea 62. As shown in the figure, the mirror part is scanned in the direction of the optical axis, and the two signal lights interfere with each other.StreaksWhen the maximum amplitude (envelope) is obtained, it is understood that the focal point Pc has reached the front surface of the cornea 62. From there, the condensing point Pc is moved little by little into the eye by moving the lens portion Pl, the mirror is scanned at each position, the maximum amplitude (envelope) at each position is compared, and secondary interference is performed.StreaksWhen the maximum value is obtained, it can be predicted that the position of the condensing point Pc has reached the rear surface of the cornea 62. Note that the arithmetic unit 210 may obtain the maximum or maximum value while scanning, or may store all scanned data in the memory 240 and obtain the maximum or maximum value later. At this time, by applying a so-called Michelson interferometer (see “Iwanami Rikagaku Dictionary” on page 1246, left column) published by Iwanami Shoten Co., Ltd.StreaksAnd secondary interferenceStreaksThe position of the mirror where the maximum amplitude (envelope) is obtained is compared, and the difference in the position of the mirror at that time is_refThen, the thickness t of the cornea 62 at that position is expressed as follows, where n is the refractive index of the cornea 62.
[0039]
[Expression 1]

It becomes. Further, the lens portion Pl from the point when the condensing point Pc reaches the front surface of the cornea 62 to the rear surface is l._Pl(= ΣΔl_Pl, Total movement)
[0040]
[Expression 2]

(R: radius of curvature of front surface of cornea 62 (calculated in advance from placido ring 71 (may be kerato ring) in step S101))
Therefore,
[0041]
[Equation 3]

It becomes. At this time,
[0042]
[Expression 4]

The primary and secondary interference of the reference mirror 14StreaksTravel distance l for detection_refAnd the amount of movement l between the anterior and posterior corneas of the lens_plThen, the refractive index n of the cornea 62 can be obtained by substituting the radius of curvature r of the front surface of the cornea 62 obtained from the measurement of the cornea shape by Plactide.
[0043]
(Vii) Calculation of the thickness of the cornea 62
Next, the obtained refractive index n of the cornea 62 and the amount of movement l of the reference mirror 14 are obtained._refFrom the above, the thickness t of the cornea 62 is calculated by the above equation (Equation 1) (S113).
As described above, the refractive index and thickness of the cornea 62 of the eye to be examined can be obtained.
Further, the illumination light is guided to the retina 61 of the eye 60 to be examined, and the reference mirror 14 can be observed up to the fifth interference fringe next to the interference fringes corresponding to the front surface and the rear surface of the crystalline lens 63 as the output of the detection means 27. The amount of movement I of the reference mirror 14 is_refAnd refractive indexes n, n of the cornea 62, aqueous humor 64, and crystalline lens 63 in the eye 60 to be examined.₁, N₂From the accurate axial length L_eye ^RCan be requested. Here, the axial length refers to, for example, the optical distance (refractive index × distance) between the anterior cornea and the retina. At this time, the output of the detection means 27 generally has the maximum amplitude of the fifth interference fringe next to the interference fringes corresponding to the front and rear surfaces of the cornea 62 and the front and rear surfaces of the crystalline lens 63. At this time, the distance from the first interference fringe to the fifth interference fringe is an accurate size of the eye axis length. The size is about 17 mm, for example.
[0044]
(Second Embodiment)
FIG. 9 is a diagram showing a schematic optical system of the eye characteristic measuring apparatus 150 according to the second embodiment. The optical system here mainly shows a case where the refractive index of the cornea, the corneal thickness, the aberration of the eye, and the shape of the cornea are measured. In addition, about the member etc. which are contained in the optical system which overlaps with the eye characteristic measuring apparatus 100 of the above-mentioned 1st Embodiment, the same code | symbol is attached | subjected and the function and a structure are the same.
For example, the first light receiving optical system 20 ′ is obtained by adding a Hartmann plate 22 to the first light receiving optical system 20 in the first embodiment. The first light receiving optical system 20 ′ includes, for example, a collimating lens 21, a Hartmann plate 22, a first light receiving unit 23, a fourth beam splitter 25 inserted between the collimating lens 21 and the Hartmann plate 22, and a collecting unit. An optical lens 26, a detection unit 27, and a first light receiving optical system moving unit 28 are provided. The Hartmann plate 22 is a conversion member that converts a part of a light beam (first light beam) reflected and returned from the retina 61 of the eye 60 to be measured into at least 17 beams. The first light receiving unit 23 is for receiving a plurality of beams converted by the Hartmann plate 22. Here, the first light receiving unit 23 is a CCD with low lead-out noise, but as the CCD, for example, a general low noise type, a cooling CCD of 1000 * 1000 elements for measurement, etc. An appropriate type can be applied.
The first illumination optical system 10 ′ includes a first light source unit 11, a condenser lens 12, a lens 12 ′, a cross cylinder lens 17, a diaphragm 18, and a moving unit 19. The moving means 19 can separately adjust the movement of the condenser lens 12 and the diaphragm of the cross cylinder lens 17. Further, when the measurement using the first light receiving unit 23 and the Hartmann plate 22 is performed, the collimating lens 92 can be moved by the condensing optical system moving unit 91 so as to be removed from the optical system.
[0045]
The eye characteristic measurement device 150 according to the second embodiment calculates the refractive index and the corneal thickness of the cornea 62 as in the first embodiment. At this time, the adjustment of the position of the condensing point is not only the movement of the collimating lens 92 by the condensing optical system moving means 91 but also the movement of the first illumination optical system 10 ′ by the moving means 19 and / or the first. It is also possible to adjust by moving the first light receiving optical system 20 ′ by the light receiving optical system moving means 28. Thereafter, the collimating lens 92 included in the condensing optical system 90 in front of the anterior eye part is removed, and eye aberration measurement is performed.
[0046]
Next, the positional relationship between the first illumination optical system 10 ′ and the first light receiving optical system 20 ′ will be schematically described for eye aberration measurement using the Hartmann plate.
A fourth beam splitter 25 is inserted into the first light receiving optical system 20 ′, and the reflected light from the eye 60 to be measured is transmitted by the fourth beam splitter 25 and included in the first light receiving optical system 20. The first light receiving unit 23 receives the light that has passed through the Hartmann plate 22 that is the conversion member, and generates a light reception signal.
[0047]
Further, the first light source unit 11 and the retina 61 of the eye 60 to be measured form a conjugate relationship. The retina 61 of the eye 60 to be measured and the first light receiving unit 23 are conjugate. The Hartmann plate 22, the pupil of the eye 60 to be measured, and the diaphragm 18 form a conjugate relationship. Further, the first light receiving optical system 20 forms a substantially conjugate relationship with the cornea 62 and the pupil, which are the anterior segment of the eye 60 to be measured, and the Hartmann plate 22. That is, the anterior focal point of the afocal lens 42 substantially coincides with the cornea 62 and the pupil, which are the anterior segment of the eye 60 to be measured.
[0048]
Further, the first illumination optical system 10 ′ and the first light receiving optical system 20 ′ assume that the light beam from the first light source unit 11 is reflected at the point where the light is collected, and signals by the reflected light from the first light receiving unit 23. Move in conjunction so that the peak is at its maximum. Specifically, in the first illumination optical system 10 ′ and the first light receiving optical system 20 ′, the direction in which the signal peak at the first light receiving unit 23 increases due to the moving unit 19 and the first light receiving optical system moving unit 28, respectively. And stop at the position where the signal peak is maximum. Thereby, the light flux from the first light source unit 11 is collected on the retina 61 of the eye 60 to be measured. At this time, the moving unit 19 may further adjust the diaphragm of the diaphragm 18. As described above, the moving unit 19 and the first light receiving optical system moving unit 28 can be used for both the measurement of the refractive index and the corneal thickness and the measurement of the aberration.
[0049]
Further, the condenser lens 12 converts the diffused light from the first light source unit 11 into parallel light. The stop 18 disposed in the vicinity of the condenser lens 12 is in an optically conjugate position with the pupil of the eye or the Hartmann plate 22. The diaphragm 18 has a diameter smaller than the effective range of the Hartmann plate 22 so that so-called single-pass aberration measurement (a method in which the eye aberration affects only the light receiving side) is established. In order to satisfy the above, the condensing lens is arranged so that the fundus conjugate point of the actual light ray is at the front focal position, and further, the rear focal position is coincident with the diaphragm in order to satisfy the conjugate relationship with the eye pupil. ing.
[0050]
Further, the light beam 15 ′ travels in the same manner as the light beam 24 in a paraxial manner after the light beam 24 and the first beam splitter 41 share a common optical path. However, in the single pass measurement, the diameters of the respective light beams are different, and the beam diameter of the light beam 15 ′ is set to be considerably smaller than that of the light beam 24. Specifically, for example, when the laser beam is incident on the eye pupil, the beam diameter of the light beam 15 is about 1 mm at the eye pupil position, and when the diffusely reflected light from the retina 61 is emitted from the eye pupil. In some cases, the distance from the first beam splitter 41 to the fundus of the light beam 15 ′ from the first light source unit 11 is omitted.
[0051]
Next, the Hartmann plate 22 as a conversion member will be described.
The Hartmann plate 22 included in the first light receiving optical system 20 is a wavefront conversion member that converts a reflected light beam into a plurality of beams. Here, a plurality of micro Fresnel lenses arranged in a plane orthogonal to the optical axis is applied to the Hartmann plate 22. In general, in order to measure the spherical portion of the eye to be measured 60, third-order astigmatism, and other higher-order aberrations of the measurement target portion (eye to be measured 60), at least via the eye to be measured 60. It is necessary to measure with 17 beams.
[0052]
The micro Fresnel lens is an optical element, and includes, for example, an annular zone having a height pitch for each wavelength and a blaze optimized for emission parallel to the focal point. The micro Fresnel lens here is, for example, an optical path length difference of 8 levels applying a semiconductor microfabrication technique, and achieves a high light collection rate (for example, 98%). The reflected light from the retina 61 of the eye 60 to be measured passes through the collimating lens 92 and the afocal lens 42 and is condensed on the first light receiving unit 23 via the Hartmann plate 22. Therefore, the Hartmann plate 22 includes a wavefront conversion member that converts the reflected light flux into at least 17 beams.
[0053]
FIG. 10 is a block diagram showing a schematic electrical system 300 of the eye optical characteristic measuring apparatus 150 according to the second embodiment. The electrical system 300 related to the eye optical characteristic measuring apparatus 150 includes, for example, a calculation unit 310, a control unit 320, a display unit 330, a memory 340, a first drive unit 350, a second drive unit 360, and a third drive. A unit 370 and a fourth driving unit 380.
[0054]
The calculation unit 310 receives the light reception signal (4) obtained from the first light receiving unit 23, the light reception signal (8) obtained from the second light receiving unit 82, the light reception signal (11) obtained from the third light receiving unit 54, and the detection means 27. , The coordinate origin, coordinate axis, coordinate movement, rotation, full wavefront aberration, surface aberration of the cornea 62, Zernike coefficient, aberration coefficient, Strehl ratio, white light MTF, Landolt ring pattern And so on. In addition, the calculation unit 310 outputs signals according to such calculation results to the control unit 320 that controls the entire electric drive system, the display unit 330, and the memory 340, respectively. Details of the processing of the calculation 310 will be described later.
[0055]
The control unit 320 controls the first drive unit 350, the second drive unit 360, the third drive unit 370, and the fourth drive unit 380 based on the control signal from the calculation unit 310. For example, the control unit 320 outputs a signal (1) to the first light source unit 11 and a signal (7) to the second light source unit 31 based on a signal corresponding to the calculation result in the calculation unit 310. , The signal (10) is output to the fourth light source unit 55, and the signal (9) is output to the third light source unit 51. Further, the control unit 320 outputs the signal (2) to the moving means 19 via the third drive unit 370, and drives the first light receiving optical system 20 with the signal (3) via the fourth drive unit 380. 1 is output to the light receiving optical system moving means 28, and further, the signal (5) is output to the condensing optical system moving means 91 via the first driving section 350, and the signal (6) is output via the second driving section 360. Output to the reference mirror moving means 16.
FIG. 11 is a flowchart of the eye characteristic measurement device 150 according to the second embodiment.
[0056]
(I) Measurement of corneal shape by platide ring 71 (S101), (ii) movement of condensing point (S103), (iii) movement of condensing optical system 90 (S105), (iv) scanning of mirror (S107), (V) Maximum value of interference fringes (S109), (vi) Calculation of refractive index (S111), (vii) Calculation of thickness of cornea 62 (S113) is the same as in the first embodiment.
[0057]
(Vii ′) Eye aberration measurement
Based on the detection result using the Hartmann plate 22, the calculation unit 310 measures the aberration of the eye before the operation by a known method (S213). Thereby, the refractive power of the eye to be examined can be evaluated.
[0058]
(Viii) Calculation of water content of cornea 62
Next, the arithmetic part 310 calculates the water content of the cornea 62 from the obtained refractive index n of the cornea 62 (S215). Specifically, the cornea 62 is divided into water and a corneal constituent (cell), and the water refractive index is 1.0 and the water content is x (%) with respect to the cornea 62.
(Corneal constituent content + x (water content)): 100 = n: 1.0
From this relationship, it is possible to calculate how much the moisture content is with respect to the entire cornea.
[0059]
(Ix) Calculation of the amount of shaving of the cornea 62 per pulse
The amount of shaving of the cornea 62 per pulse is calculated from the water content of the cornea 62 (S217). That is, specifically, the amount of water evaporation per pulse is determined in step S215 because the excimer laser is scraped off at a predetermined depth (for example, 0.4 to 0.7 μm) by the apparatus. The depth of the cornea 62 that evaporates in one pulse is determined with respect to the water content, and the amount of the cornea 62 that is scraped off can be known.
[0060]
(X) Refractive surgery
A refractive surgery for the cornea 62 is performed according to the obtained water content of the cornea 62 (S219). In addition, refractive surgery can be performed in parallel while measuring the corneal thickness.
[0061]
(Xi) Calculation of refractive index
After the refractive surgery performed in step S219, the refractive index is calculated again in the same manner as described above (S221). The details are the same as the processing in steps S101 to S111 described above, and are omitted here.
[0062]
(Xii) Calculation of the thickness of the cornea 62
After the refractive surgery, the thickness of the cornea 62 is obtained again in the same manner as described above (see S113) (S223). As a result, it is confirmed whether or not the operation was properly performed.
[0063]
(Xiii) Eye aberration measurement
Based on the detection result using the Hartmann plate 22 and / or the platid ring 71, the calculation unit 310 measures the post-operative eye aberration (corneal aberration) by a known method (S225). Thereby, the refractive power of the eye to be examined can be evaluated.
Note that the calculation of the refractive index in step S221 may be omitted.
[0064]
(Third embodiment)
FIG. 12 is a diagram showing a schematic optical system of the eye characteristic measuring apparatus 170 according to the third embodiment. The schematic optical system here mainly shows the case where the measurement of the thickness of the cornea and the aberration of the eye is performed using a zoom lens. In addition, about the member etc. which are contained in the optical system which overlaps with the above-mentioned eye characteristic measuring apparatus 100, the same code | symbol is attached | subjected and the function and a structure are the same.
The eye characteristic measuring device 170 here includes, for example, a zoom lens optical system 90 '. This zoom lens optical system 90 'adjusts the optical system instead of making the condensing optical system 90 of the eye characteristic measuring apparatus 150 in the second embodiment removable. Note that the schematic diagram of FIG. 3 corresponds to the eye characteristic measuring apparatus 170 according to the third embodiment.
The block diagram of the electric system is the same as that of the second embodiment, but the control of the zoom lens optical system 90 'is different. That is, the zoom lens optical system 90 ′ includes a collimator lens 92 and a zoom lens 93, and the signal (5) in FIG. 12 moves the zoom lens moving means 94 via the fifth drive unit 490, and the collimator lens 92. Further, by changing the surface interval that is the interval between the zoom lenses 93, the condensing point can be condensed on the cornea 62, or the aberration can be measured by entering the parallel light. Therefore, the refractive index, the corneal thickness, the eye aberration, and the like of the cornea 62 can be measured without removing the condensing optical system 90 as in the first and second embodiments. The flowchart of eye characteristic measurement is the same as that of the second embodiment.
[0065]
Note that the second illumination optical system 70 and the adjustment optical system of the above-described eye characteristic measurement devices 100, 150, and 170 are used to measure the peripheral part other than the central part of the cornea 62 and create a shape map of the entire cornea. Further, the corneal thickness can be measured by scanning the entire surface of the pupil (part or part). By doing so, it is possible to measure all or part of the corneal thickness at a time and grasp the shape of the entire cornea as a map.
[0066]
(Fourth embodiment)
As in the case of measuring the corneal thickness, the boundary surface where the refractive index changes from the interference fringes detected by the calculation unit and the detection means 27 as shown in the first embodiment, FIG. 5, FIG. 6, and FIG. (Aqueous humor-lens, lens-vitreous, vitreous-retina) is detected, and the refractive index n of the lens 63 and the eye 60 (vitreous) to be examined.₁, N₀To calculate the axial length L_eye ^RIs calculated.
Calculated axial length L_eye ^RBased on this, the power on the axis of the eye to be examined is calculated, and a power map is output from the aberration map of the eye 60 to be examined.
Here, the position of the target wavefront is indicated by X and Y, and in the cross section including the optical axis, the point where the normal of the wavefront at that position intersects the optical axis, and the wavefront on the optical axis at that time Let Lp be the distance to the position. The power P at this time is 1 / Lp + 1 / L_eye ^RAnd Where L_eye ^RRepresents the axial length of the eye accurately measured as described above. The power distribution at each position (r, t) on the wavefront is represented by P (r, t). This power distribution P (r, t) corresponds to the refractive power distribution of the eye (Ocular Refractive Power Map).
[0067]
Next, the Power Map calculation method will be described.
First, a case where the obtained wavefront aberration W (X, Y) is converted into a power display will be described. This power display is mainly shown in first to fifth display examples described later.
Here, the position of the target wavefront is indicated by X and Y, and in the cross section including the optical axis, the point where the normal of the wavefront at that position intersects the optical axis, and the wavefront on the optical axis at that time L to the position of_PAnd
The power P at this time is 1 / L_P+ 1 / L_eye ^RAnd Where L_eye ^RIs the accurately measured axial length of the eye.
Conventionally, a general ocular axial length is estimated to be 17 mm, the power on the axis of the eye to be examined is calculated, and a power map is output from the aberration map of the eye 60 to be examined. The axial length is calculated, the power on the axis of the eye to be examined is calculated, and the power map can be output from the aberration map of the eye 60 to be examined.
[0068]
【The invention's effect】
According to the present invention, as described above, the function of measuring the shape and thickness of the cornea and the refractive index using low coherent interference is added to the conventional eye characteristic measuring device, and the aberration of the eye to be examined, the cornea after surgery Since the shape and the like can be obtained and the amount of corneal scraping can be calculated in refractive surgery, the cornea can be accurately operated in corneal correction surgery.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic optical system of an eye characteristic measuring apparatus 100 according to the present invention.
FIG. 2 is a configuration diagram of a placido ring 71.
FIG. 3 is a block diagram showing a schematic electrical system 200 of the eye characteristic measuring apparatus 100 according to the present invention.
FIG. 4 is a flowchart of the eye characteristic measuring apparatus 100 according to the first embodiment.
FIG. 5 is a diagram (1) illustrating a relationship between a moving distance of a reference mirror 14 and a detection unit 27;
6 is a diagram (2) showing the relationship between the moving distance of the reference mirror 14 and the detection means 27. FIG.
7 is a diagram (3) showing the relationship between the moving distance of the reference mirror 14 and the detection means 27. FIG.
FIG. 8 is a schematic diagram for explaining a method of calculating a refractive index of the cornea 62.
FIG. 9 is a diagram showing a schematic optical system of an eye characteristic measuring apparatus 150 according to the present invention.
FIG. 10 is a block diagram showing a schematic electrical system 300 of an eye optical property measuring apparatus 150 according to the present invention.
FIG. 11 is a flowchart of an eye characteristic measuring apparatus 150 according to the present invention.
FIG. 12 is a diagram showing a schematic optical system of an eye characteristic measuring apparatus 170 according to the present invention.
[Explanation of symbols]
10 First illumination optical system
14 Reference mirror
20 First light receiving optical system
22 Hartmann board
30 Second light transmission optical system
40 Common optics
41 Optical path splitting optical system (first beam splitter)
50 Adjustment optical system
60 Eye to be measured
61 Retina
62 cornea
70 Second illumination optical system
71 Pratide ring
80 Second light receiving optical system
90 Condensing optical system
100, 150, 170 Eye characteristic measuring device

Claims (9)

A first light source that emits a light beam having a wavelength in the near infrared region;
An optical path dividing means for guiding a part of the light beam emitted from the first light source part to the anterior eye part to be examined and taking out a part of the light beam as reference light;
Condensing means for condensing the light beam from the first light source unit on the anterior eye portion to be examined;
Reflecting means for reflecting the reference light from the optical path dividing means;
Detecting means for detecting interference fringes formed through the optical path dividing means from the reflected light from the anterior segment of the eye to be examined and the reference light reflected by the reflecting means;
First moving means for moving a condensing point in the vicinity of the anterior eye part of the eye to be examined, in which the light flux from the first light source part is collected by the condensing means;
Second moving means for moving the reflecting means in the optical axis direction;
The cornea of the eye to be inspected based on the detection result of the interference fringes by the detecting means while the movement of the condensing point at the anterior eye part of the eye to be examined is controlled by the first moving means and the reflecting means is moved by the second moving means. An arithmetic unit for obtaining a refractive index or a corneal thickness is provided ,
The calculation unit calculates an corneal refractive index and / or a corneal thickness based on the calculated curvature radius of the front surface of the cornea and a moving distance by the first and second moving means. A first light source that emits a light beam having a wavelength in the near infrared region;
An optical path dividing means for guiding a part of the light beam emitted from the first light source part to the anterior eye part to be examined and taking out a part of the light beam as reference light;
Condensing means for condensing the light beam from the first light source unit on the anterior eye portion to be examined;
Reflecting means for reflecting the reference light from the optical path dividing means;
Detecting means for detecting interference fringes formed through the optical path dividing means from the reflected light from the anterior segment of the eye to be examined and the reference light reflected by the reflecting means;
First moving means for moving a condensing point in the vicinity of the anterior eye part of the eye to be examined, in which the light flux from the first light source part is collected by the condensing means;
Second moving means for moving the reflecting means in the optical axis direction;
The cornea of the eye to be inspected based on the detection result of the interference fringes by the detecting means while the movement of the condensing point at the anterior eye part of the eye to be examined is controlled by the first moving means and the reflecting means is moved by the second moving means. An arithmetic unit for obtaining a refractive index or a corneal thickness is provided ,
The said calculating part controls the said condensing means to be removed from an optical system by the said 1st moving means, and measures the aberration of an eye to be examined, The eye characteristic measuring apparatus characterized by the above-mentioned. A first light source that emits a light beam having a wavelength in the near infrared region;
An optical path dividing means for guiding a part of the light beam emitted from the first light source part to the anterior eye part or the retina to be examined and taking out a part of the light beam as reference light;
Condensing means for condensing the luminous flux from the first light source part on the anterior eye part or the retina to be examined;
Reflecting means for reflecting the reference light from the optical path dividing means;
Detecting means for detecting interference fringes formed through the optical path dividing means from the reflected light from the anterior eye part or retina of the eye to be examined and the reference light reflected by the reflecting means;
First conversion means for converting a part of the first reflected light beam reflected from the retina of the eye to be examined into at least substantially 17 beams, the first light beam from the first light source unit;
First light receiving means for receiving a beam via the conversion means;
First moving means for moving a condensing point in the vicinity of the anterior eye part of the eye to be examined, in which the light flux from the first light source part is collected by the condensing means;
Second moving means for moving the reflecting means in the optical axis direction;
The corneal refraction of the eye to be inspected based on the detection result of the interference fringes by the detecting means while controlling the movement of the condensing point at the anterior segment of the eye to be examined by the first moving means and the movement of the reflecting means by the second moving means. An eye characteristic measuring apparatus comprising a calculation unit that obtains a rate or a corneal thickness and obtains an aberration of the eye to be examined by reflected light from the eye retina detected by the first light receiving means. In the eye characteristic measuring device according to any one of claims 1 to 3 ,
The calculation unit obtains the interval between the maximum or maximum amplitude of the interference light detected by the detection means from the movement distance of the second movement means, and obtains the corneal refractive index or the corneal thickness of the eye to be examined from the movement distance. An eye characteristic measuring device. In the eye characteristic measuring device according to any one of claims 1 to 3 ,
A second illumination optical system for illuminating the vicinity of the anterior eye portion of the eye to be examined; and a second light receiving portion for detecting reflected light from the anterior eye portion of the eye to be examined,
The arithmetic unit is an eye characteristic measuring device, wherein a corneal shape or corneal aberration of an eye to be examined is obtained from a detection result by the second light receiving unit. In the eye characteristic measuring device according to claim 3 ,
The calculation unit calculates an corneal refractive index and / or a corneal thickness based on the calculated curvature radius of the front surface of the cornea and a moving distance by the first and second moving means. In the eye characteristic measuring device according to claim 3 ,
The condensing optical system is a zoom lens optical system, and the cornea refractive index or corneal thickness of the eye to be examined is obtained by adjusting the condensing point and detecting the interference fringes by the detecting means in accordance with the control by the first moving means. An eye characteristic measuring apparatus for obtaining an aberration of an eye to be examined by detecting reflected light from the retina of the eye to be examined by the first light receiving means. In the eye characteristic measuring device according to claim 3 ,
Condensing means for adjusting the focal position of the light beam from the first light source;
Stop means for adjusting the stop of the light beam from the first light source;
Condensing diaphragm moving means for adjusting and controlling the position and diaphragm of the condensing means and the diaphragm means,
The arithmetic unit adjusts the position of the condensing point and the detected light beam by the first light receiving unit by controlling the condensing stop moving unit. In the eye characteristic measuring device according to any one of claims 1 to 3 ,
In order to detect the interference fringes at each position by scanning the position of the condensing point of the light beam applied to the anterior segment of the eye to measure the corneal thickness and / or corneal refractive index of a part or all of the pupil An eye characteristic measuring device further comprising scanning means.

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