Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2001-10-25
2004-02-10
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
C351S212000
Reexamination Certificate
active
06688745
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to optical instruments for developing a corrective ophthalmic prescription and, more particularly, to apparatuses and methods for subjectively refining a corrective prescription based on aberrations determined by a wavefront measuring device (WMD).
BACKGROUND OF THE INVENTION
The eye is an optical system having several optical elements for focusing light rays representing images onto the retina within the eye. The sharpness of the images produced on the retina is a factor in determining the visual acuity of the eye. Imperfections within the lens and other components and material within the eye, however, may cause the light rays to deviate from the desired path. These deviations, referred to as aberrations, result in blurred images and decreased visual acuity. Hence, methods and apparatuses for measuring aberrations are used to aid in the correction of such problems.
One method of detecting aberrations introduced by the eye involves the determination of aberrations introduced into light rays exiting from the eye. An input beam of light focused into the eye to a point on the retina is reflected or scattered back out of the eye as a wavefront. The wavefront contains the aberrations introduced as the wavefront passes through the eye's optical elements and exits the eye. By determining the propagation direction of discrete portions (i.e., samples) of this wavefront, the aberrations can be determined, thereby enabling the production of corrective lenses and/or performance of other corrective procedures that restore visual acuity.
FIG. 1
is an illustration of a prior art WMD
10
for measuring aberrations within a wavefront
100
and correcting aberrations. An input beam
102
generated by a radiation source
104
(e.g., a laser) is routed to an eye
106
by a beam splitter
108
where it is focused to a small spot
110
on the retina
112
within the eye
106
. The wavefront
100
reflected from the spot
110
on the retina
112
, which acts as a diffuse reflector, becomes aberrated as it passes through the lens and other components and materials within the eye
106
. In an ideal eye, the wavefront
100
would be free of aberrations. In an imperfect eye
106
, however, aberrations are introduced as the wavefront
100
passes out of the eye
106
and results in an imperfect wavefront containing aberrations.
On the return path, the wavefront
100
passes through the beam splitter
108
to a sensor
114
that includes, for example, a Hartman-Shack lenslet array
116
and an imaging device
118
containing a charge coupled device (CCD). A quarter-wave plate
120
, positioned between the eye
106
and the beam splitter
108
, is a known technique for manipulating the polarization of the input beam
102
going into the eye
106
and the wavefront
100
emanating from the eye
106
to allow the wavefront
100
to pass through the beam splitter
108
toward the wavefront sensor
114
. Additional lenses
122
are positioned between the eye
106
and the wavefront sensor
114
to image the plane of the pupil of the eye
106
onto the wavefront sensor
114
with a desired magnification. Information detected by the wavefront sensor
114
is then processed by a processor
124
to determine the aberrations of the wavefront
100
, which can be used to develop a corrective prescription for the eye
106
.
While the WMD
10
depicted in
FIG. 1
is able to determine aberrations introduced by the eye
106
with a high degree of accuracy, the development of a corrective prescription needs to be precisely tailored to a patient's visual needs. In addition, vision correction involves a perceptual aspect (i.e., psychophysics) that cannot be captured with conventional WMDs. It is therefore desirable to obtain subjective feedback from the patient during the development of the corrective prescription. Accordingly, methods and apparatuses for subjectively refining corrective prescriptions based on aberrations determined by WMDs are needed. The present invention fulfills this need among others.
SUMMARY OF THE INVENTION
The present invention discloses methods and apparatuses for subjectively refining corrective prescriptions based on aberrations determined by WMDs. In the present invention, an image is altered to reflect the corrective prescription and presented to a patient. Feedback is received from the patient to vary the corrective prescription, and further alter the image, which is again presented to the patient for further feedback. This process is repeated until the image presented to the patient is acceptable to the patient. The corrective prescription at this point becomes the patient's preferred corrective prescription.
One aspect of the present invention is a method for obtaining a preferred corrective prescription for an eye of a patient. The method includes measuring aberrations of a wavefront emanating from the eye, computing a proposed corrective prescription based on the measured aberrations, presenting to the patient an image altered to reflect the proposed corrective prescription, receiving feedback from the patient about the image altered to reflect the proposed corrective prescription, varying the proposed corrective prescription based on feedback from the patient, presenting to the patient an image altered to reflect the varied corrective prescription, and receiving feedback from the patient about the image altered to reflect the varied corrective prescription. The corrective prescription is then varied based on feedback from the patient and an image altered to reflect the varied corrective prescription is presented to the patient for feedback, repeatedly, to obtain the preferred corrective prescription.
Another aspect of the present invention is an apparatus for obtaining a preferred corrective prescription for an eye of a patient. The apparatus includes a WMD capable of measuring aberrations of the eye, a processor configured to determine a proposed corrective prescription including one or more components based on the measured aberrations, a display device to present an image reflecting the corrective prescription to the patient, and an input device capable of varying at least one of the one or more components based on feedback from the patient to obtain the preferred corrective prescription.
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G. Walsh, W.N. Charman and H.C. Howland, “Objective technique for the determination of monochromatic aberrations of the human eye”, Sep. 1984, vol. 1, No. 9, pp. 987-992.
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Junzhong Liang, Bernhard Grimm, Stefan Goelz, and Josef F. Bille, “Objective measurement of wave aberrations of the human eye with the use of Hartman-Shack wave-front sensor”, Jul. 1994, vol. 37, No. 3, 1 page.
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PCT International Search Report
Bille Josef
Mueller Frank
Ross Denwood F.
Schottner Michael
Johnson & Johnson Vision Care Inc.
Manuel George
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