JPH0341925A - Ophthalmological measuring device - Google Patents

Abstract

PURPOSE:To exactly execute the measurement even if its place is not a complete darkroom by providing a light shielding plate on the front position of an eye to be examined which can bring a background light which is reflected by the eye to be reflected and made incident on the optical path of a light receiving optical system, to light shielding. CONSTITUTION:A laser beam P from a light source 2 is condensed by a condenser lens 3, and irradiates the front part 6 of an eye to be examined 5 by a projection lens 4. A scattering light N in an eyeball is condensed from the oblique direction by using the light receiving lens 9 of a light receiving optical system 8, and led to a photomultiplier 13 through a half mirror 11 and a diaphragm 12. The half mirror 11 leads a part of the scattering light N to an ocular lens 15. In front of the eye 5, that is, in a position for bringing a background light 22 which is made incident on an optical path 24 to light shielding, a light shielding plate 25 for preventing the background light 22 from being reflected by the surface of the cornea 21 and being made incident on the optical path 24 is provided. In such a manner, even if there is a misalignment against the eye 5, it is prevented that its background light 22 is made incident on the optical path 24, and the measurement can be executed exactly.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention comprises a convergent light irradiation optical system so that a convergent light beam is irradiated toward the eyeball of an eye to be examined, and the reflection of the convergent light beam on the eyeball. This invention relates to an improvement in an ophthalmological measuring device that calculates and measures the condition of an eyeball by guiding scattered light based on the light receiving optical system to a measuring device equipped with a charging converter or an image intensifier.

(Prior Art) Conventionally, ophthalmological measurement devices have been configured with a convergent light irradiation optical system so that a convergent light beam is irradiated toward the eyeball of the eye to be examined, and the scattering based on the scattering of this convergent light by the eyeball has been used. There is a configuration in which light is guided through a light receiving optical system to a measuring device equipped with a photoelectric converter or an image intensifier, and the state of the eyeball is calculated and measured, and the calculated measurement results are displayed.

(Problems to be Solved by the Invention) However, in this conventional ophthalmological measurement device, since the amount of scattered light from the eyeball is extremely weak, the background light in the measurement chamber is reflected by the eye to be examined, and the measurement optical system If the light enters the optical path of the light, it will cause noise, and it will be easily affected by the background light, so the measurement must be carried out in a completely dark room, making the measurement difficult.

The present invention has been made in view of the above circumstances, and its purpose is to provide an ophthalmological measuring device that can perform accurate measurements while avoiding the effects of background light even in a not completely dark room. It is about providing.

(Means for Solving the Problems) In order to achieve the above object, the ophthalmological measurement device based on the present invention has a position where background light that is reflected by the eye to be examined and enters the optical path of the light receiving optical system can be blocked. It is characterized in that a light shielding plate is provided at a position in front of the eye to be examined.

(Operation and Effect) According to the ophthalmological measuring device according to the present invention, background light that may be reflected by the eye to be examined and enter the optical path of the light receiving optical system is blocked by the light shielding plate, so that it does not need to be in a completely dark room. Measurements can be made accurately.

(Example) Hereinafter, an example in which the ophthalmological measuring device according to the present invention is applied to the measurement of intracameral white matter concentration will be described with reference to the drawings.

In FIG. 1, 1 is a laser beam irradiation optical system, and 2 is a He--Ne laser light source that forms a part of the laser beam irradiation optical system. The laser beam P from the He-Ne laser light source 2 is condensed by the condenser lens 3, and is irradiated into the anterior chamber 6 in the eyeball of the subject @5 as a convergent beam by the projection lens 4. The laser beam P is φ scattered within the eyeball (for example, scattered at the measurement point 7), and the scattered light N is transmitted to the optical axis 10 of the eye 5 using the light receiving lens 9 of the light receiving optical system 8 that defines the measurement field of view S. The light is focused from an oblique direction relative to the light beam, and is guided to a photomultiplier tube (PMT) 13 via a half mirror 11 and an aperture 12. Here, half mirror
Reference numeral 11 has a function of guiding a part of the scattered light N to an eyepiece lens 15 which forms a part of the observation optical system 14 at the bottom.

A parallel plane plate 16 is provided between the half mirror 11 and the aperture 12.
is provided. When the parallel plane plate 16 is set perpendicular to the optical axis 17 of the light-receiving lens 9 as shown in FIG. and the optical axis 17 as shown in FIG.
When set obliquely with respect to the measurement field S-, scattered light N- from the measurement field S- is guided to the photomultiplier tube 13 through the aperture 12a.

This photomultiplier tube 13 converts photons into electrons, and
It has an amplification function and outputs the photoelectric conversion outputs S1 and S2 (see FIG. 4) to the amplifier 18. Amplifier 9 #18 amplifies the photoelectric conversion output and connects it to arithmetic circuit 1 as an arithmetic measurement means.
Output to 9. The calculation circuit 19 has a function of counting and calculating the intensity of the scattered light N%N' as the number of photons. The arithmetic circuit 19 calculates the measurement field of view S by subtracting the measurement result of the measurement field of view S- from the measurement result of the measurement field of view S.
The opacity of the anterior chamber 6, which is extremely important in determining intraocular inflammation and the permeability of the blood aqueous humor fence, is removed by removing noise components from within the eyeball included in the measurement, and the calculation results are as follows: Display of turbidity value etc. on monitor etc.11
)20. Regarding the groove bottom mentioned above, the ophthalmological measuring device (
It is disclosed in Japanese Patent Application No. 63-265813).

By the way, if such a measurement is performed in a room that is not a completely dark room, an image 23 based on the background light 22 is reflected on the cornea 21 of the eye 5 to be examined, as schematically shown in FIG.
The background light 22 forming this image 23 may enter the optical path 24 of the light receiving optical system 8 as shown in FIG. When this background light 22 enters the optical path 24 of the light receiving optical system 8,
Noise components based on this background light 22 are included in the measurement results, making it impossible to obtain accurate measurement results.

Therefore, in this ophthalmological measuring device, the background light 22 is placed in front of the eye 5 to be examined and at a position where the background light 22 entering the optical path 24 of the light receiving optical system 8 can be blocked by the surface of the cornea 21 of the eye 5 to be examined. A light shielding plate 25 is provided to prevent the light from being specularly reflected and entering the optical path 24 of the light receiving optical system 8 . A diffuser plate or a non-reflection plate is used for this light shielding plate 25.

As a result, even if there is a misalignment of the device main body with respect to the eye 5 to be examined and the room is not completely dark and a distorted reduced image is formed on the cornea 21 based on the background light, the background light 22 from entering the optical path 24, accurate measurements can be made.

In the above embodiments, an ophthalmological measuring device for measuring opacity in the anterior chamber has been described, but the present invention can also be applied to an ophthalmic measuring device for testing the cornea, crystalline lens, fundus, and the like.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main part configuration of the ophthalmological measuring device according to the present invention, FIGS. 2 and 3 are schematic diagrams for explaining the action of the parallel plane plate shown in FIG. 1, and FIG. 5 is an explanatory diagram of the photoelectric conversion output output from the photomultiplier tube, and FIG. 5 is a schematic diagram for explaining the image formed on the cornea of the eye to be examined due to background light. 1... Laser light irradiation optical system, 5... Eye to be examined 8...
・Light receiving optical system, 9... Light receiving lens, 25... Light shielding plate K... Convergent light flux, N, N-... Scattering sibling diagram

Claims (1)

[Claims] (1) A laser beam irradiation optical system is configured so that a laser beam as a convergent beam is irradiated toward a measurement point on the eyeball of the eye to be examined, and the scattered light based on the scattering of the laser beam at the measurement point is In an ophthalmological measurement device that determines a field of view for measurement and guides the light to a photoelectric converter via a light receiving optical system, and calculates and measures the condition of the eyeball based on the photoelectric conversion output of the photoelectric converter, the light reflected by the eye to be examined and the received light. 1. An ophthalmological measuring device, characterized in that a light shielding plate is provided at a position in front of the subject's eye at a position capable of shielding background light incident on the optical path of an optical system.