Kabushiki Kaisha Topcon

Hideki Hatanaka

Fumio Ohtomo

Tsutomu Sato

Akihiro Arai

Hisashi Tsukada

Akihiko Sekine

Takeyuki Kato

Isao Minegishi

Minoru Kamiya

A corneal shape measuring apparatus is provided which measures a corneal shape in such a way that a reflection image from a cornea (15) is recorded as image data and then the image data is analyzed. The apparatus includes LEDs (14) for projecting an index onto a subject's eye in order to detect a position of an apparatus body (3) in up, down, right, and left directions and in forward and backward directions with respect to the eye, an automatic photographic mode in which the eye is automatically photographed when a position of the apparatus body in up, down, right, and left directions with respect to the and a position of the apparatus body in forward and backward directions with respect to the eye are each within a predetermined range, a semi-automatic photographic mode in which the eye is photographed when a position of the apparatus body in up, down, right, and left directions with respect to the eye and a position of the apparatus body in forward and backward directions with respect to the eye are each within the predetermined range and, at the same time, a photography switch (11') is operated, and a manual photographic mode in which the eye is photographed when the photography switch is operated regardless of a position of the apparatus body with respect to the eye. A positional relationship of the apparatus body (3) to the eye is stored correspondingly to recorded image data.

Corneal shape measuring apparatus

An intraocular length measuring instrument according to the invention can avoid errors in measurement caused by the movement of a subject's eye, such as a blink or involuntary eye movement, and improve the accuracy of the measurement of an intraocular length of the eye. The intraocular length measuring instrument includes a pattern image projecting and receiving optical system for projecting a pattern image onto the cornea of the eye and receiving the pattern image into a two-dimensional image sensor; an interferometric system for producing interference light in such a way that measuring light is projected onto a surface of an intraocular object to be measured while reference light is projected onto a reference surface corresponding to the object surface and interference is caused between light reflected by the object surface and light reflected by the reference surface and causing a photosensor to receive the interference light and output an interference signal; a device for determining the position of the object surface by sampling interference signals output by the photosensor; a device for reading the data concerning the pattern image received by the two-dimensional image sensor at any point of time of the duration of the sampling in order to memorize the pattern image data in a memory medium; and means for determining the position of a corneal vertex from the pattern image data memorized in the memory medium.

Intraocular length measuring instrument capable of avoiding errors in

An intraocular length measuring instrument including a light source having a short coherent length, a beam splitter for forming a measuring optical path across the interior of an eye to be tested and a reference optical path within the instrument, and guiding a beam of light from the light source to both the measuring optical path and the reference optical path, a first light receiving portion for interfering light reflected by an intraocular object to be measured after passing along the measuring optical path with light coming through the reference optical path and receiving a resultant interference light, an intraocular object position measuring portion for finding an optical path difference from an optical path length of the reference optical path and a peak position of a signal coming from the first light receiving portion, a light irradiating optical system for irradiating a light beam to the cornea of the eye to be tested, a light receiving optical system for introducing a reflected light from the cornea to a second light receiving portion, and a corneal position measuring portion for fining a position of the cornea from an output of the second light receiving portion.

Intraocular length measuring instrument

Growing community of inventors

Tokyo, Japan

Hideki Hatanaka