JP2897211B2 - Optometry device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slit lamp microscope capable of measuring the curvature of a cornea, and particularly to an apparatus suitable for inspection for prescription of a contact lens and confirmation of a fitting state. [Prior art] The prescription of a contact lens is as follows. First, a refractometer or the like is used to screen the refraction abnormality of the eye to be examined, and the corrective refractive power is determined by a subjective test, and the radius of curvature of the cornea of the eye to be examined is measured by a keratometer. Measure and select a trial lens from both data. Thereafter, a trial lens is attached to the subject's eye to check whether pain is caused, and a fitting inspection using a fluorescence reflection image using a slit lamp microscope is performed. However, conventionally, all these operations have been performed using separate and independent devices. Further, as an apparatus combining a slit lamp microscope and a corneal curvature meter, for example, an apparatus disclosed in Japanese Patent Publication No. 61-25369 is known. This is a structure in which the main objective lens of the slit lamp microscope and the corneal curvature meter can be exchanged by rotation. [Problems of the prior art] In order to perform the former prescription of a contact lens using a separate and independent device, a large space for inspection is required, and both the examiner and the subject must move between the devices. There are inconveniences that must be met. The latter is a combination device of a slit lamp microscope and a manual corneal curvature meter, and can only detect a curvature in one certain meridian direction, so that it is difficult to obtain an accurate corneal astigmatism and an axial angle. An object of the present invention is to provide a compact slit lamp microscope capable of saving a large amount of space and labor when prescribing a contact lens, and capable of measuring curvature with high accuracy independent of the experience of an examiner in view of the problems of the above-described conventional apparatus. Is to provide. [Constitution of the Invention] In order to achieve the above object, the present invention provides a slit lamp microscope having a slit light projection optical system for projecting slit light and an observation optical system for observing an eye to be inspected including a magnification changing means, A corneal reflection image of the measurement target is detected through a projection optical system that projects the measurement target toward the cornea, and a measurement light reflecting unit that reflects the light flux of the measurement target and transmits at least a part of the visible light flux. A corneal curvature measurement optical system including a detection optical system, and the measurement light beam reflection means is placed between the observation optical system and the subject's eye during measurement of the corneal curvature, and the measurement light beam reflection means is used for the observation optical system during slit observation. Moving means for moving the corneal curvature measurement optical system so as to be placed outside the optical path,
Display means for displaying a measurement result by the corneal curvature measurement optical system; and approximately anterior eye of the eye to be examined in conjunction with moving the measurement light beam reflecting means between the observation optical system and the eye by the movement means. Control means for operating the magnification changing means so that the entire section can be observed. Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an arrangement diagram of a basic optical system of the slit lamp microscope. Reference numeral 1 denotes an examinee's eye, and 2 denotes an examiner's eye. 3 is an observation optical system and 25 is an illumination optical system. The light beam emitted from the illumination light source 26 is condensed by a condenser lens and then formed into a slit shape by an aperture 28 and a slit plate 29. 30 is a filter, consisting of several replaceable filters including a cobalt filter. For a fitting inspection using a fluorescence reflection image, a cobalt filter is inserted on the optical path. The light beam transmitted through the filter 30 is applied to the slit projection lens 3
1. It is projected onto the subject's eye via the prism 32 and illuminates it. The illumination optical system is arranged so as to be pivotable about a vertical axis V, and can be pivoted to enter and exit the optical path of the observation optical system. The observation optical system 3 includes an objective lens 4, a variable power mechanism 5 composed of a Galileo system variable power lens group, a relay lens 6, a Porro prism 7, a field stop 8, and an eyepiece 9. Is observed through the eyepiece 9. Corneal Curvometer (Measurement Principle) FIG. 3 is a view for explaining the measurement principle of the corneal curvature radius in this embodiment. When an annular indicator (not shown) is projected onto the cornea, a circle having a radius a is formed when the cornea is spherical, and an ellipse having a major axis b ₁ and a minor axis b ₂ is formed when the cornea is a toric surface. Here, it is assumed that points (A) and (B) on a circle correspond to (A ') and (B') on an ellipse. Further, assuming that the ellipse is inclined from the x axis by (θ) about the origin 0, the x and y components of the amount of change from (A) to (A ′) are (ΔAx) and (ΔA
When the x and y components of the amount of change from (y) and (B) to (B ′) are (ΔBx) and (ΔBy), respectively, the following relationship is established. ΔAx = b ₁ cos ² θ + b ₂ sin ² θ−a (1) ΔAy = b ₁ −b ₂ ) sin θ cos θ (2) ΔBx = (b ₁ −b ₂ ) sin θ cos θ (3) ΔBy = b ₁ cos ² θ + b ₂ sin ² θ−a (4) Accordingly, b ₁ , b ₂ , and θ can be expressed by the following equations. Further, the position of (A ') and the target point (C') are detected, and the center between the two points (A ') and (C') is obtained to obtain the position of the origin 0. Thus, each of the points (A), (B) and (C) on the reference circle
The x, y coordinates are stored in advance, and the x, y of each of the points (A '), (B'), and (C ') formed by the cornea having an unknown shape.
By detecting the coordinates, the corneal shape can be measured. Next, the relationship between the elliptical shape and the corneal toric surface shape will be described with reference to FIG. The collimated point light source 13 is projected onto the cornea at an angle α with respect to the optical axis 0. When the distance from the optical axis 0 of the image 13 'that can be at this time is b _1, the corneal radius of curvature Rb ₁ in the cross section can be expressed by the following equation. Similarly, if the distance from the optical axis 0 and b _2, the corneal radius of curvature Rb ₂ in this section can be expressed by the following equation. By substituting Equations (5) and (6) into Equations (8) and (9), R on the long side and R on the short side can be obtained. (Optical System) Next, an optical system constituting the corneal curvature meter will be described. FIG. 1 is an arrangement diagram of a basic optical system of a corneal curvature meter. The aiming optical system of the corneal curvature meter is shared with the observation optical system 3 of the slit lamp microscope except for the Meyerring projection system. 10 includes a part of the detection optical system and the target projection system,
It is a movable part that can be put in or out of the detection system. The movable unit 10 is rotatable about the optical axis 0 '. When the curvature meter is not used, the movable unit 10 is rotated and removed from the aiming optical system (observation optical system) 3. It should be noted that the species to be put in or out is not limited to this, and it is needless to say that the species may be slid on the rail from the up-down direction. Also, when the movable part is put into the aiming / detection system, the magnification change mechanism in the observation optical system (aiming optical system) is set to the lowest magnification so that the anterior eye can be observed in a wide range. In the present embodiment, the setting is performed manually, but a known method,
That is, the operability is further improved by interlocking the switching of the aiming system and the detection system by operating a switch using a microcomputer. The movable unit 10 includes a Meyerring projection system for aiming, a target projection system, and a part of a detection optical system. The visible light flux emitted from the Meyer ring light source group 11 forms a ring-shaped virtual image on the cornea 15 of the subject's eye by the ring-shaped slit plate 12. The examiner observes the Meyerring image through the eyepiece lens 9 and positions the image so that the image can be seen most clearly at the center of the visual field. The point light sources 13a and 13B of the optotype projection system are light sources having wavelengths in the near infrared region. When the measurement switch (not shown) is pressed after the completion of the alignment, the measurement light flux is emitted from the point light sources 13a and 13b. The emitted light beams are collimating lenses 14a and 14B
And is projected at an angle of α onto the cornea 15 of the subject's eye, and is specularly reflected on the corneal surface to produce virtual images 13a ′ and 13
Make b '. The measurement light beam reflected by the cornea of the subject's eye is reflected by the dichroic mirror 16 and guided to the detection optical system. With the objective lens 17, the light receiving surface 24 of the one-dimensional sensor array and the virtual image 13a ',
13b 'and 13c' are arranged at conjugate positions and the objective lens 1
The light is reflected by the light beam mirror 18 having emitted the light 7 and changes its direction. A telecentric stop 20 is arranged at the image-side focal position of the objective lens 17, and a light beam passing through the telecentric stop 20 is split into two optical paths by a beam splitter 21. A cylindrical lens common to the one-dimensional sensor array 24 in the divided optical path
23 are placed. The light is polarized on the one-dimensional sensor array by the prism action of the cylindrical lens, and becomes a blurred line image in a direction orthogonal to the detection direction of the one-dimensional sensor array due to its refractive power. An image rotator 22 inclined at 45 ° about the optical axis 0 ″ is disposed on one of the optical paths split by the beam splitter 21, and the light beam passing therethrough is 90 ° about the optical axis 0 ″.
After being rotated by an angle, the light enters the one-dimensional sensor array 24. The X and Y coordinates of the virtual images 13a 'and 13b' on the cornea are obtained by taking out the scanning output of the measuring light incident on the one-dimensional sensor array 24 and measuring the interval between peak outputs corresponding to each point light source image. Can be In this case, the X coordinate is measured by a light beam passing through the optical axis 0 ", and the Y coordinate is measured by a light beam passing through the optical axis 0 '. After obtaining the position coordinates of 13a' and 13b ', And point light source 1 in the same way.
A point light source 13c (not shown) at a position where 3a is rotated by 90 ° with respect to the optical axis 0 forms a virtual image 13c 'and obtains the position coordinates of this virtual image. The radius of curvature of the cornea is calculated based on the coordinates thus obtained, and displayed on a display (not shown). In this embodiment, the measurement is performed separately in the vertical direction and the horizontal direction. However, the measurement can be performed simultaneously by providing a prism between the cylindrical lens 23 and the one-dimensional sensor array 24. [Effects of the Invention] According to the present invention, anterior eye observation with a slit lamp microscope, fitting inspection, which is indispensable for prescription of a contact lens,
The corneal curvature measurement can be performed efficiently with one device,
Moreover, there is no need to separately provide an observation optical system for measuring the corneal curvature. Furthermore, complicated mounting adjustment work for corneal curvature measurement is not required, the measurement result can be obtained immediately without any special operation, and the appearance of the slit lamp microscope is not impaired. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a layout diagram of a basic optical system of a corneal curvature meter, FIG. 2 is a layout diagram of a basic optical system of a slit lamp microscope, FIG. 3 and FIG. It is a figure explaining the measurement principle of a corneal curvature radius. 3: Observation optical system (aiming optical system) 10: Moving part, 21: Beam splitter 22: Image rotator

Continuation of front page       (56) References JP-A-61-220624 (JP, A)                 JP-A-62-117525 (JP, A)                 JP-A-53-32992 (JP, A)                 Real opening sho 59-68503 (JP, U)                 Mishima et al., "Ophthalmology MOOK No.               3 General Examination of Ophthalmology ”Kanehara Publishing (Showa 55-               10-20), P189

Claims (1)

(57) [Claims] A slit lamp microscope having a slit light projection optical system for projecting slit light and an observation optical system for observing the subject's eye including a zooming means, a projection optical system for projecting a measurement index toward the cornea, A corneal curvature measurement optical system that includes a detection optical system that detects a corneal reflection image of the measurement index via a measurement light beam reflection unit that reflects the light flux of the index and transmits at least a part of the visible light flux, and when measuring corneal curvature, Moving means for moving the corneal curvature measuring optical system so that the measuring light beam reflecting means is placed between the observation optical system and the eye to be inspected, and the slit is used to place the measuring light beam reflecting means outside the optical path of the observation optical system. Display means for displaying a measurement result by the corneal curvature measurement optical system; and a test object interlocked with moving the measurement light beam reflection means between the observation optical system and the eye by the moving means. An optometry apparatus comprising: control means for operating the zooming means so that substantially the entire anterior segment of the eye can be observed.