JPH09197352A - Trial lens for inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that prescription is difficult and prescription exchange is frequent by providing the optical part of the concave surface part of a lens with a toric surface which has two orthogonal radii of curvature and specifying the degree of astigmatism of one surface. SOLUTION: This trial lens for inspection has the features that the optical part of the concave surface part of the lens has the toric surface which has two orthogonal radii of curvature (RB1 and RB2 shown by the expression) and the RB2 surface has the degree of astigmatism shown by the expression. The expressions are RB1>= the weak main meridian value of the cornea, RB2 > the strong meridian value of the cornea, and the degree of astigmatism of the trial lens =(NT-1.00)×(1/RB1-1/RB2)×1000. In the expressions, the units of RB1 and RB2 are millimeters. Further, NT is the refractive index of tear liquid. A trial lens for inspection like this is used to improve the stability of the lens at the time of inspection, the need for eye drop anesthesia is eliminated, and the inspection can easily be performed similarly to the inspection of an ordinary spherical lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to astigmatism correction using a hard contact lens, and more particularly to an examination trial lens for determining a astigmatism correction contact lens for a patient with corneal astigmatism.

[0002]

2. Description of the Related Art As a method of correcting astigmatism, a method using a spectacle lens and a method using a contact lens are known. In the case of strong corneal astigmatism, the method using spectacle lenses often does not provide sufficient corrected visual acuity, but in the case of contact lenses, good corrected visual acuity is often obtained, which is expected as a method of correction. . However,
Since the prescription method for contact lenses is difficult, it has not spread enough. The following three types of methods are known as methods for correcting astigmatism with contact lenses, especially for patients with corneal astigmatism.

1) A method using a spherical lens. 2) Back toric lens method. 3) Method using a bite lick lens. The causes of astigmatism are roughly classified into corneal astigmatism and residual astigmatism (such as crystalline lens astigmatism).

In the case of only corneal astigmatism, it can be often corrected by a spherical lens, but it is not used so much due to the problem of wearing feeling. A back toric lens is used to improve this feeling of wearing, but a huge number of trial lenses are required to make an accurate prescription, and it is economically impossible, so a simple trial lens set Since the prescription is performed in Japan, it requires experience in prescription and hinders its spread. A considerable part of spherical lenses and back toric lenses are set so that the shape of the optical part of the concave surface part distorts the cornea, and therefore the prescription data predicted from the perfect correction value for spectacle lenses is large. The prescription results are different. This point is also considered to be the reason why prescriptions for astigmatism correction are difficult.

It was thought that the Bite-Rick lens requires less experience in prescribing because it can be prescribed from the perfect correction value for spectacle lenses, but inspection data for prescribing (corneal shape data, corrective spherical power and astigmatic power). Due to insufficient accuracy in), it is difficult to form an accurate prescription and it is not widely used.

[0006] Recently, in order to improve this point, a prescription method for trial lenses for bitoric lenses has been developed (JP-A-2-24421). In this method, a spherical lens is used as a trial lens, a truncation is provided to stabilize the lens on the cornea, and eye anesthesia is required at the time of examination. Therefore, inspection with this trial lens requires a considerable amount of skill and labor, which hinders its widespread use.
Also, with this method, the corrective spherical power can be accurately obtained,
Corrected astigmatic power is still uncertain. As described above, the astigmatism correction method using contact lenses has not been widely used despite its expected effects due to the large number of prescription exchanges due to difficulty in prescription and insufficient patient satisfaction.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of difficulty in prescription and frequent replacement of prescription, which are problems in astigmatism correction with hard contact lenses. . The present invention provides an improved test trial lens for overcoming the difficulty of prescriptions and the high number of prescription changes.

[0008]

[Means for Solving the Problems] The difficulty of prescription lies in the difficulty of examination with a trial lens and the inaccuracy of the corrected astigmatic power. In the present invention, in order to solve these two points, as a result of earnest studies, the inventors have invented the following trial lens for inspection. That is, according to the present invention, two curvature radii (RB1 represented by the following formula,
An inspection trial lens having a toric surface having RB2) and having an astigmatic power of the following formula on the RB2 surface.

RB1 ≧ weak main meridian value of cornea RB2> strong main meridian value of cornea Astigmatic power of trial lens = (NT-1.00) ×
(1 / RB1-1 / RB2) × 1000 (Here, the units of RB1 and RB2 are expressed in millimeters, and NT is the refractive index of tear fluid.)

The present invention will be described in detail below. The trial lens for inspection of the present invention has two radii of curvature RB1 and RB2 which are orthogonal to each other in the concave surface optical portion, and the values thereof are as follows. RB1 ≧ weak main meridian value of cornea RB2> strong main meridian value of cornea This strong / weak main meridian value of the cornea can be measured by a keratometer or an off-salmometer. The measured value is read in units of 1/100 mm, but it is desirable to round up this value to the unit of 0.05 mm. On the strong main meridian side, it is desirable to further carry it by 0.05 mm. The difference between RB1 and RB2 is not particularly limited, but if this difference is too small, the stability of the astigmatic axial degree may deteriorate. In the case of a trial lens for inspection, it is 0.30 mm or more, preferably as standard.
35 mm.

The trial lens for inspection of the present invention is RB
It is necessary that the two surfaces have the astigmatic power calculated by the following equation. Astigmatic power of trial lens = (NT-1.00) x
(1 / RB1-1 / RB2) × 1000 Here, NT is the refractive index of tear fluid, and 1.3375 was used in the present invention. The spherical power of the trial lens is not particularly limited, but -3.00D is preferable as the standard as in the trial of the spherical lens.

In the present invention, the use of the above-mentioned trial lens for inspection improves the stability of the lens during the examination, eliminates the need for eye anesthesia, and is almost the same as the trial examination with a normal spherical lens. It will be similarly easy to implement. The difference between the weak main meridian value and the strong main meridian value is not particularly limited as the cornea shape, but if this difference is small, the stability of the astigmatic axial degree of the lens may deteriorate. It is preferable that this difference is 0.40 mm or more.

In the present invention, by using the above-mentioned trial lens for inspection, the corneal astigmatic power due to the shape of the cornea is already almost corrected by this trial lens. This is because the corneal astigmatic power is almost canceled by the tear lens power, but only the tear lens part that disappeared by giving the concave part two curvature radii to have lens stability. It became possible only by correcting as the astigmatic power of this trial lens. In the correction visual acuity test using this trial lens for inspection, it is only necessary to confirm the additional spherical power and the additional astigmatic power of the same axis as the corneal astigmatic axis only when there is residual astigmatism, and the inspection is easy. Can be implemented.

The trial lens set for inspection of the present invention is not particularly limited, but it is sufficient to prepare the same number as the trial lens set for a normal spherical lens, for example. In other words, the base curve is 0.05mm
It may be prepared at intervals, for example, BC = 7.20-8.
Within the range of 40, 25 sheets / set is sufficient. In this case, the size of the base curve on the strong main meridian side of the cornea is made smaller than this value by a constant value, regardless of the shape of the cornea, based on the size of the base curve on the weak main meridian side of the cornea. Is desirable. The constant value is not particularly limited, but is preferably 0.30 mm or more, more preferably 0.35 mm or more.

The contact lens for astigmatism correction prescribed by the trial lens for inspection of the present invention has a toric surface having two radii of curvature (RB1, RB3) orthogonal to the optical portion of the concave surface portion, and their values are respectively. It is indicated by the following values. RB1 ≧ weak main meridian value of cornea RB3> strong main meridian value of cornea The strong / weak main meridian value of the cornea can be measured by a keratometer or an off-salmometer. The measured value is read in units of 1/100 mm, but it is desirable to round up this value to the unit of 0.05 mm. On the strong main meridian side, it is desirable to further raise the distance by 0.05 mm or more. The difference between RB1 and RB2 is not particularly limited, but if this difference is too small, the stability of the astigmatic axial degree may deteriorate, so it is preferably 0.30 m.
m or more, and more preferably 0.35 mm or more.

The astigmatism correction contact lens prescribed by the examination trial lens of the present invention has the RB2 surface having the astigmatic power calculated by the following equation. Astigmatic power of lens = (NT-1.00) × (1 / RB1
−1 / RB2) × 1000 + Cyl Here, NT is the refractive index of tear fluid, and 1.3375 was used in the present invention. Further, here, Cyl is the additional astigmatic power confirmed by the corrected visual acuity test result with the above-described trial lens.

The spherical power of the lens is a value obtained by adding the spherical power of the trial lens for inspection and the additional spherical power confirmed by the above-mentioned corrected visual acuity test. The method for producing the trial lens for inspection of the present invention is not particularly limited, and it can be performed by a method known to those skilled in the art. For example, DAC DL
L SERIES III / 4XC LATHE or Max Gfeller AG
There is a method of using a special lathe such as Type AT-3, JT-2, or a method of using a spherical lathe with the conventional bending method.

[0018]

In the present invention, the base curve and the astigmatic power of the contact lens for astigmatism correction are determined by the method using the above-mentioned trial lens for inspection, which facilitates the determination method and reduces prescription exchange. Is possible. This was made possible by offsetting the effect of corneal astigmatism with a tear lens to compensate for the difficulty of measuring astigmatism power, and by adding little or no residual astigmatism. It is due to. Also,
Even when determining the base curve, this trial lens can be inspected in a stable wearing state, so it can be confirmed in a state close to the prescription lens including the feeling of wearing by the patient, and the prescription lens like the conventional There is no need to understand it without trying.

[0019]

Hereinafter, the present invention will be described in detail with reference to Examples which are compared with Comparative Examples. Comparative Example 1 Prescription Example with Spherical Lens (YY) The following data were obtained as the radius of curvature of the cornea and subjective / objective refraction test data. 1. Corneal curvature radius 7.89 / 7.42 AX180 2. Subjective Refraction Test Data 1.5XS-4.00C-1.25AX180 3. Objective Refraction Test Data S-4.0C-1.50AX179

Corrected visual acuity data obtained using the following trial lenses and prescription lens data from the results are as follows. 4. Trial lens data 7.65 S-3.00C-0.00AX 5. Corrected visual acuity data 1.2XS-0.75C-1.25AX180 6. Prescription data 7.65 1.2XS-3.75C-1.25AX180

The lens data calculated from the above data 1, 2, and 4 are as follows. 7. Calculation data 7.65 S-3.75C-1.50AX90 The calculation results were significantly different from the prescription data, and it was difficult to predict from the refraction test data. The prescription lens had a prescription exchange because of a feeling of foreign matter and poor eyesight.

Comparative Example 2 Prescription Example (DT) with Back Toric Lens The same inspection results as in Comparative Example 1 were obtained. 1. Corneal radius of curvature 8.66 / 7.70 AX159 2. Subjective Refraction Test Data 1.0XS + 6.25C-2.50AX180 3. Objective refraction test data S --- C --- AX-

Corrected visual acuity data obtained using the following trial lenses and prescription lens data from the results are as follows. 4. Trial lens data 8.30 / 7.80 S-3.00C-3. 53AX 5. Corrected visual acuity data 1.2XS + 6.25C-0.00AX 6. Prescription data 8.30 / 7.80 1.2XS + 3.75C-3.53AX

The lens data calculated from the above data of 1.2 and 4 are as follows. 7. Calculation data 8.30 / 7.80 S + 5.00C-0.25AX180 As a result of the calculation, the spherical powers were greatly different, and it was difficult to predict from the refraction inspection data. The prescription lens was replaced due to poor fitting.

Comparative Example 3 Prescription Example (O.K.) with Spherical Lens The same inspection results as in Comparative Example 1 were obtained. 1. Corneal curvature radius 7.79 / 7.07 AX176 2. Subjective Refraction Test Data 1.0XS + 0.25C-3.50AX170 3. Objective Refraction Test Data S + 0.25C-4.50AX172

Corrected visual acuity data obtained using the following trial lenses and prescription lens data from the results are as follows. 4. Trial lens data 7.75 S-2.00C-0.00AX 5. Corrected visual acuity data 1.0XS + 2.25C-0.00AX 6. Prescription data 7.75 / 7.15 1.2XS + 0.25C-3.75AX 180

The lens data calculated from the above data 1, 2, and 4 are as follows. 7. Calculation data 7.75 / 7.15 S + 0.00C-2.75AX180 As a result of the calculation, the spherical diopter is almost the same, and the astigmatic diopter is also 1.
It was within D and could be predicted from the refraction test data. Examination with a trial lens required eye anesthesia. There was no particular problem in wearing the prescription lens.

Example 1 Prescription Example (KO) for Trial Lens for Inspection The same inspection result as in Comparative Example 1 was obtained. 1. Corneal radius of curvature 7.76 / 7.02 AX180 2. Subjective Refraction Test Data 1.0XS + 1.00C-3.75AX180 3. Objective Refraction Test Data S + 0.75C-4.50AX179

Corrected visual acuity data obtained using the following trial lenses and prescription lens data from the results are as follows. 4. Trial lens data 7.75 / 7.40 S + 0.25C-2.06 AX180 5. Corrected visual acuity data 1.2XS + 0.75C-0.00AX 6. Prescription data 7.75 / 7.10 1.2XS + 1.00C-4.00AX 180

The lens data calculated from the above data 1, 2, and 4 are as follows. 7. Calculation data 7.75 / 7.10 S + 1.00C-3.25AX180 As a result of the calculation, the spherical diopter was present, the astigmatic diopter was also within 1D, and the prediction from the refraction test data was also possible. The trial lens examination did not require eye anesthesia. There was no particular problem in wearing the prescription lens.

(Example 2) Prescription Example (SK) for Trial Lens for Inspection The same inspection results as in Comparative Example 1 were obtained. 1. Corneal curvature radius 7.23 / 6.69 AX178 2. Subjective Refraction Test Data 1.2XS + 2.75C-3.25AX175. Objective Refraction Test Data S + 3.25C-3.00AX172

Corrected visual acuity data obtained using the following trial lenses and prescription lens data from the results are as follows. 4. Trial lens data 7.20 / 6.85 S-3.00C-2.40 AX180 5. Corrected visual acuity data 1.0XS + 5.25C-0.00AX 6. Prescription data 7.20 / 6.75 1.0XS + 2.25C-3.25 AX180

The lens data calculated from the above data 1, 2 and 4 are as follows. 7. Calculation data 7.20 / 6.75 S + 2.50C-2.50AX180 As a result of the calculation, the spherical power is almost the same, and the astigmatic power is also 1.
It was within D and could be predicted from the refraction test data. The trial lens examination did not require eye anesthesia. There was no particular problem in wearing the prescription lens.

[0034]

According to the present invention, the trial lens set can be selected in accordance with only the radius of curvature of the cornea, like the trial lens set for spherical lenses. is there. This is because the astigmatic power of the trial lens of the present invention is set so that the test can be performed regardless of the corneal astigmatic power.

In the present invention, even in the case of intense corneal astigmatism,
Since no special skill or experience is required, it is possible to handle the lens almost as easily as the prescription of a spherical lens. This is because by using the trial lens of the present invention, the base curve, the spherical surface, and the astigmatic power can be easily obtained by calculation based on the measured values. As a result, even if you have little experience prescribing contact lenses for astigmatism correction, it is now possible to prescribe as easily and accurately as with spherical lenses. It is expected that more opportunities will be provided and better vision correction will be performed.

Since the trial lens for examination of the present invention hardly distorts the shape of the cornea, the examination result is
Since it almost matches the perfect correction value of the spectacle lens, it is possible to easily determine whether or not the prescription data of the astigmatism correction contact lens is correct. Therefore,
The prescription technique can be easily improved on the basis of the prescription technique of the conventional spectacle lens.

Claims (3)

[Claims] 1. A toric surface having two radii of curvature (RB1 and RB2 represented by the following equation) orthogonal to the optical portion of the concave surface of the lens, and an RB2 surface having an astigmatic power of the following equation. Trial lens for inspection. RB1 ≧ weak main meridian value of cornea RB2> strong main meridian value of cornea Astigmatic power of trial lens = (NT-1.00) ×
(1 / RB1-1 / RB2) × 1000 (Here, the units of RB1 and RB2 are expressed in millimeters, and NT is the refractive index of tear fluid.) 2. NT = 1.375 and RB1-R
2. A range of B2 ≧ 0.30.
Trial lens for inspection described. 3. The trial lens for inspection according to claim 2, wherein RB1−RB2 ≧ 0.30 and RB1 is a value obtained by rounding up the weak main meridian value of the cornea in units of 0.05 mm. .