Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-03-24
2001-05-15
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06231186
ABSTRACT:
FIELD OF INVENTION
The present invention generally relates to a system for measuring the total axial distance of an eye. More specifically, the present invention relates to a system where the measurements of a biometric ruler are combined with the measurement of an anterior segment analyzer.
DESCRIPTION OF RELATED ART
Biometric rulers, also commonly known as A-scan devices or ultrasonic probes, are well known in the art. These devices typically transmit an ultrasonic pulse through a probe device which is in contact with the patient's cornea. The pulse waves are reflected back from the components of the eye and received by the ruler. The time it takes for certain echo reflections to be received can be related to distance values through well known equations.
An error in the measurement of the total axial length of the eye with the biometric ruler is often introduced by the need for the probe transducer to contact the cornea surface. This contact often causes a slight depression or flattening of the cornea, which introduces error into the distance measurements of the biometric ruler. The anterior segment analyzer, on the other hand, does not require any contact with the cornea surface and therefore its measurements are not subject to the error of the biometric ruler.
However, the anterior segment analyzer cannot provide a distance measurement to the posterior surface of the lens or the retina and therefore cannot give a complete axial length measurement to each particular surface along the axial length of an eye.
It is also known to use an ultrasonic transducer in combination with a ultrasound gel such that the probe can be held above the cornea without depressing it. If the cornea is not depressed an accurate axial distance measurement of the eye can be achieved but it is very uncomfortable and messy for the patient.
Therefore, a need exists to provide a system that would eliminate the error introduced by the use of the biometric ruler and yet provide distance measurement information in a quick convenient manner.
REFERENCES:
patent: 4764006 (1988-08-01), Hamano et al.
patent: 5116114 (1992-05-01), Nakamura et al.
patent: 5728156 (1998-03-01), Gupta et al.
Broadus Charles R.
Turner Timothy N.
Bausch & Lomb Surgical, Inc.
Manuel George
Smith Michael L.
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