Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-05-31
2001-07-10
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06257722
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ophthalmic apparatus, and more particularly to an alignment mechanism of the apparatus relative to a patient's eye.
2. Description of Related Art
Referring to the ophthalmic apparatus such as an ophthalmic laser surgery apparatus, a refractometer, a noncontact tonometer, a fundus camera or the like, after the patient's eye fixes a fixation target to fix a position of an eyeball, a desired part of the patient's eye is aligned with the apparatus (such as optical axis of the following optical system: a laser irradiating optical system, a measuring optical system, a photographing optical system or the like) to carry out surgery, measurement, photographing or the like of the patient's eye. Deviation between the patient's eye and the apparatus may occur due to movement of the patient's eye (the eyeball) after alignment. Every time when the deviation occurs, manually-operated alignment is inconvenient. For this reason, currently, a mainly used type of apparatus is the one detects positional relationship between the patient's eye and the apparatus to move the apparatus relative to the patient's eye to perform alignment.
As for the ophthalmic laser treatment apparatus, it is well known that a corneal surgery apparatus which irradiates a corneal surface with an excimer laser beam to ablate a lesion on the corneal surface or to change the corneal curvature to correct refractive errors. For instance, in this kind of the apparatus, movement of the patient's eyeball may occur while the laser irradiating. However, the examiner may not recognize this movement and keeps the laser irradiating, which results in ablating the cornea in a not-predetermined shape. For the prevention of this error, it is suggested to provide the ophthalmic apparatus with a function of moving an irradiating optical axis of the laser irradiating optical system to perform tracking of the patient's eye. In this kind of tracking mechanism, an anterior part of the eye is consistently photographed with a CCD photographing element while the laser irradiating. Then, in the case of detecting that the pupil center position or the like are not positioned within a predetermined allowable range relative to the irradiating optical axis or the like as a standard position, the tracking of the irradiating optical axis is performed in a manner to make the pupil center position or the like coincide with the standard position based on the photographing image.
As for the above-mentioned CCD photographing element for position detecting, a CCD photographing element for interlaced scanning which alternately outputs image data (image signals) of an odd field and of an even field is generally used because such a CCD photographing element is economical. However, this CCD photographing element requires about 33 ms to obtain a screenful of image data. For this reason, in case that the movement of the patient's eye is fast, it results in decreasing accuracy of tracking and operation.
In addition, it is suggested that the apparatus which projects target luminous flux on the patient's cornea and photographs a target image (bright spot) formed on the cornea with the CCD photographing element to perform tracking based on the results. However, in case that the patient's eye moves fast, which results in decreasing accuracy of tracking and surgery.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances and has an object to overcome the above problem and to provide the ophthalmic apparatus which can increase accuracy of surgery or measurement by speeding up alignment of the patient's eye and the apparatus.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed our in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, an ophthalmic apparatus comprises ophthalmic means having an observation optical system for observing a patient's eye and treating or examining the patient's eye, moving means for relatively moving the ophthalmic means relative to the patient's eye, a photographing optical system including a plurality of photoelectric photographing elements for photographing the patient's eye, image capturing means which captures image signals of different ranges from the plurality of photoelectric photographing elements to obtain supplemental image data, detecting means which analyzes the obtained image data to detect a position of the patient's eye, and control means which controls the moving means based on the results detected by the detecting means to move the ophthalmic means to a desired position relative to the patient's eye.
In another aspect of the present invention, an ophthalmic apparatus comprises ophthalmic means having an observation optical system for observing a patient's eye and treating or examining the patient's eye, moving means for relatively moving the ophthalmic means relative to the patient's eye, a photographing optical system including a plurality of photoelectric photographing elements for photographing the patient's eye, detecting means which captures images signals of interlaced scanning from the plurality of photoelectric photographing elements at time intervals and detects a position of the patient's eye based on the captured image signals, and control means which controls the moving means based on the results detected by the detecting means to move the ophthalmic means to a desired position relative to the patient's eye.
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patent: 5562656 (1996-10-01), Sumiya
patent: 5562691 (1996-10-01), Tano et al.
patent: 5637109 (1997-06-01), Sumiya
patent: 6022108 (2000-02-01), Yoshida et al.
patent: 6082860 (2000-07-01), Takagi
patent: 0 765 648 A2 (1997-04-01), None
patent: 5-22667 (1993-01-01), None
patent: 10-145654 (1998-05-01), None
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Manuel George
Nidek Co. Ltd.
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