Kabushiki Kaisha Topcon

Topcon Corporation

Canon Kabushiki Kaisha

Akinari Takagi

Hiroshi Iijima

Kouji Nishio

A corneal endothelial cell photographing apparatus comprises a first slit plate provided with a slit, a photographing light projecting optical system for obliquely projecting photographing light for photographing a corneal endothelial cell of an eye to be tested through the slit of the first slit plate on the eye, an observation light projecting optical system for projecting observation light through the slit of the first slit plate on the eye for observation prior to photographing the corneal endothelial cell of the eye, an observing and photographing optical system for guiding the observation light reflected from the cornea of the eye and the photographing light reflected from the cornea of the eye to an image pickup device for the observation and photographing of the corneal endothelial cell of the eye, a second slit plate provided with a slit narrower than that of the first slit plate, and a Z-alignment measuring light projecting optical system for projecting alignment measuring light through the slit of the second slit plate on the eye to measure the position of a main unit of the corneal endothelial cell photographing apparatus relative to the eye with respect to directions along the optical axis of the eye.

Corneal endothelial cell photographing apparatus

An ophthalmic apparatus having a main unit detects the alignment of the main unit with the subject's eye with respect to vertical and lateral directions by an XY-alignment detecting means on the basis of an index light beam projected on the eye and reflected from the cornea of the eye, detects the alignment of the main unit with the eye with respect to horizontal directions parallel to the optical axis of the eye by a Z-alignment detecting means on the basis of a Z-alignment index light beam projected obliquely on the eye and reflected from the cornea of the eye, and permits a display means to display the results of detection made by the Z-alignment detecting by a display permitting means when a predetermined condition is satisfied.

Ophthalmic apparatus

A noncontact tonometer is provided which is capable of intercepting out-of-axis light of an index beam of light and performing precise alignment. The noncontact tonometer includes an index projecting optical system for projecting an index frontally onto a subject's eye (E) through a nozzle (12) through which gas is also is sprayed upon the eye (E). The index projecting optical system has a projection lens (27) and a diaphragm (23) disposed at a position conjugated to an end surface (F) of the nozzle (12) on the side of the projection lens (27). The diaphragm (23) intercepts rays of light traveling out of an optical axis, and enables precise alignment.

Noncontact tonometer

An ophthalmologic apparatus is provided which comprises a slit light projecting optical system (60) for projecting a slit beam of light from an oblique direction onto the cornea (C) of a subject's eye, a light receiving optical system (70) for receiving light reflected by the cornea (C), a corneal thickness measuring circuit (74) for measuring the thickness of the cornea from information on the received light of the light receiving optical system (70), an index light projecting optical system (90) for projecting from an oblique direction onto the cornea (C) an index beam of light having a larger width than the slit beam, and a line sensor (72) for receiving the index beam reflected by the cornea (C).

Ophthalmologic apparatus

Disclosed herein is an ophthalmic instrument equipped with an optical alignment system. The optical alignment system has a Z-alignment index projection light system (60) which projects index light onto the cornea (C) of a subject eye (E) and a sensor (73) which receives reflected light of the index light reflected at the cornea (C). The ophthalmic instrument is further equipped with a Z-alignment detection circuit (74) which computes a positional relation between an index image formed on a light receiving surface of the sensor (73) and the cornea (C). When the result of computation by the detection circuit (74) is within a predetermined range, the subject eye is measured. The Z-alignment index projection light system (60) is provided with an aperture diaphragm (63) which has a transmittance distribution characteristic in which a quantity of light is gradually reduced from the optical axis of the system (60) in a radial direction.

Ophthalmic instrument

A non-contact tonometer measures an intraocular pressure precisely based on a deformation amount of a cornea when a pressurized pulse of air is injected to the cornea. The intraocular pressure is measured on the basis of the maximum value of a correlation function curve, instead of detecting a peak of a light changing curve.

Non-contact tonometer

An ophthalmological instrument is provided in which optical members can be satisfactorily cleaned, the times for cleaning can be reduced and reliability of measuring accuracy can be improved. An alignment between a cornea (C) of an eye (E) to be tested and an instrument body is detected by projecting an alignment detecting light toward the cornea (C) through alignment detecting optical systems (30, 40) and receiving a luminous flux reflected on the cornea (C) through a light receiving sensor (45). A working distance between the cornea (C) and the instrument body is detected projecting a working distance detecting light toward the cornea (C) through working distance detecting optical systems (50, 60) and receiving a luminous flux reflected on the cornea (C) by a light receiving sensor (63). Part of optical paths of the alignment detecting optical systems (30, 40) and the working distance detecting optical systems (50, 60) are not used in common. Dirt stuck to optical members arranged in part of the optical paths which are used in common is detected in accordance with signals from the light receiving sensors (45, 63).

Ophthalmological instrument

An alignment luminous flux is projected toward the cornea of an eye-to-be-detected by an alignment light projecting optical system. The alignment luminous flux reflected by the cornea is imaged on two light receiving means by an alignment light imaging optical system one of which light receiving means is disposed on the front side of an light collecting position adjacent to the cornea when the cornea is in a correct working distance and the other of which is on the back side.

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Tokyo, Japan

Akinari Takagi