Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
1998-08-21
2001-07-31
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06267477
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a three dimensional imaging apparatus and a method for use thereof. More specifically the present invention relates to a retinal tissue components size and thickness analyzer apparatus. The said invention furthermore relates to a non invasive measurement method for measuring retinal thickness imaging and for visualizing retinal cross sections by using said apparatus. The aparatus according to the said invention incorporates laser and conventional optics with computerizes signal analysis in order to measure pathological indications in the eye and in order to identify normal occular physiology. This allows for improved diagnosis for various ophthalmic diseases such as diabetic retinopathy and glaucoma, and also for improved monitoring of therapeutic effects.
BACKGROUND OF THE INVENTION
The two main causes of blindness in the western world are diabetic retinopathy and glaucoma.
One of the most important pathologies of diabetic retinopathy is macular edema. Over a lifetime, about 30% of the people with diabetes will develop macular edema. Nonproliferative diabetic retinopathy with Clinically Significant Macular Edema (CSME) includes either (a) thickening of the retina at or within 500 microns of the center of the macular or (b) hard exudes at or within 500 microns of the center of the macular if associated with thickening of the adjacent retina (not residual hard exudates remaining after the disappearence of retinal thickening) or (c) a zone or zones of retinal thickening 1 disk area or larger, any part of which is within 1 disk diameter of the center of the macula. Patients with CSME should be considered for treatment.
The assessment of retinal thickening by slit lamp biomicroscopy and/or stereo fundus photography is often difficult, not accurate, and of questional reliability. Moreover, the current methods typically necessitate a time consuming involvement of a highly skilled observer. Currently there is no commercially available method, capable of detecting and mapping quantitatively retinal thickening. Thus accurate assessment of CSME in patients remains subjective even though the clinical criteria of CSME are quantitative. The present invention enables the necessary objective quantitative measurements to be performed.
Loss of vision from glaucoma is largely preventable through early diagnosis and therapy. While the level of Intra occular Pressure (IOP) is strongly correlated with the risk of glaucoma optic nerve damage, a substantial proportion of patients with glaucoma (one sixth or more) have not had demonstratable or repeated elevations of IOP above 21 mm Hg. Conversely, many individuals with IOP repeatedly above 21 mm Hg do not have, and may never develop, optic nerve damage during their lifetime.
Screening procedures for identifying patients at significant risk for glaucomatous visual field loss are most effective when IOP measurements are combined with an assessment of the optic nerve and a review of other potential occular and systemic risk factors. This approach is already part of the “Comprehensive Adult Eye Examination”, which may constitute the single most important screening/diagnostic setting to identify patients at risk and a subset of those at particularly “high risk” for glaucoma.
Visible structural alterations of the optic nerve or nerve fiber layer frequently occur before visual defects can be measured, even with the most sensitive current techniques. While measures of both structure and function are important to detect early glaucomatous damage, careful and repeated examination of the optic nerve and nerve fiber layer may provide the earliest signs of damage by demonstrating progressive damage before definitive visual field abnormalities appear. The present invention allows an objective method for nerve fiber layer damage assessment.
SUMMARY OF THE INVENTION
The present invention relates to a three dimentional imaging scanning apparatus for retinal thickness and structure non-invasive analysis. The present invention also relates to a method for the use of said apparatus.
The apparatus according to the present invention is comprised of at least one optical path having:
(A) A high brightness light source or a laser which provides a beam for illuminating a selected portion of the retinal tissue.
(B) A means for simultaneous focusing said beam going to the retina and returning from the retina wherein the said focusing means are common for both the beam going to and comming from the retina.
(C) An optical beam deflector which is common for both the beam going to and coming from the retina.
(D) An aperture for defining the angle between the beam going to the retina and returning from the retina.
(E) A detection means for detection of the returned beams and determination of the retinal thickness.
(F) A camera for imagining the pupil/iris is preferably added, which enables accurate longitudinal and perpendicular positioning of the beam from (A) on the pupil.
(G) A fundus camera for imagining the whole Fundus preferably added, which enables accurate longitudinal and perpendicular positioning of the beam from (A) on the retina.
The present invention further relates to a method for imaging the eye and its components using the apparatus according to the present invention, comprising;
(a) simultaneously using three optical paths for scanning the retina using a common optical beam deflector or deflectors to illuminate a predetermined zone of the retina and to acquire an image of said zone, while vibrating said beam deflector during said illumination/acquisition time, and said vibrations improve the image quality; imaging the whole Fundus; and imaging of the pupil/iris;
(b) subsequently spatially integrating one or more of said imagings into an eye model.
DETAILED DESCRIPTION OF THE INVENTION
The retinal thickness analyzer apparatus according to the present invention operates basically on the principle of slit lamp biomicroscopy. A narrow slit of light (laser light as a prefered embodiment) is projected onto the retina. The light scattered back from the retina is viewed by an electronic camera at an angle relative to the angle of the incident light. This provides a quantitative measurement of the retinal thickness cross-section topography for the specific retinal area selected and optical sectioning of the retina.
During one measurement the slit of light is scanned over a number of positions on the retina so that the resulting image represents a number of cross-sections of the retina covering a square area of for example 2×2 mm. It is possible for example that nine adjacent squares are scanned to provide coverage of about 6×6 mm (20°×20°) around the fovea, disk, or any other interesting zone. Likewise numerous contiguous or dispersed areas of the retina can be measured and the resulting three dimentional representations of the whole scanned area can be represented to enable a clinical and scientific evaluation. The retinal examination with the retinal thickness analyzer apparatus according to the present invention is performed in a manner similar to Fundus photography. After the eye is dilated and the patient is seated in the headrest of the apparatus, the apparatus is positioned along the optic axis of the eye at the correct working distance with reference to the iris display which shows a high magnification image of the iris of the examined eye. After alignment an image of the stationary slit on the retina is displayed, the focus adjustment knob is used to focus this image.
After focusing the scan is initiated. The display shows a set of slit images obtained at the positions scanned before. A thickness map, that can be displayed and/or stored for future reference, is generated by computer processing of the scanned slit images, within a short time. Different regions on the retina are scanned by translating the subjects fixation point. This is accomplished with the internal fixation target which is projected on the retina of the subjects eye. An external fixation light is also available f
Karpol Avner
Zeimer Ran
Lowe Hauptman & Gilman & Berner LLP
Manuel George
Talia Technology Ltd.
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