Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2001-02-21
2003-02-18
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06520640
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an apparatus and method for acquiring, analyzing and imaging of three dimensional retinal data.
More specifically the present invention relates to a non invasive apparatus and method for measuring retinal thickness, surface topography and other features relating to the structure of the retina together with digital imaging of the retina, and correlating said structure with the retinal image.
BACKGROUND OF THE INVENTION
The main cause of blindness in the western world is diabetic retinopathy. 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.
Non-proliferative 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 macula or (b) hard exudates at or within 500 microns of the center of the macula if associated with thickening of the adjacent retina (not residual hard exudates remaining after the disappearance 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.
Recently a Retinal Thickness Analyzer (RTA) apparatus has been developed (U.S. Pat. No. 4,883,061). The RTA apparatus allows for visual inspection and for quantitative measurements of the retinal thickness, the amount of nerve fiber layer on the retina, the topography of the retinal surface, particularly that of the optic nerve head, and other additional features of the retina.
U.S. Pat. No. 5,742,374 teaches a fundus camera for photographing the fundus of an eye. The apparatus is provided with a ring slit illumination for peripheral illumination of the fundus. European Patent Publication No. 412667 teaches a fundus examining device including an optical system for observing an anterior portion of the eye. The apparatus disclosed is U.S. Pat. No. 5,742,374 and European Patent Publication No. 412667 are disadvantageous since the apparatuses disclosed do not enable analysis of the retinal thickness.
WO9730627 discloses a three dimensional imaging scanning apparatus for determining the retinal thickness and structure of the eye using non-invasive analysis. Optical paths and cameras are included for imaging both the whole fundus and the retinal thickness. For purposes of measurement of a specific region of the retina, both fundus imaging and imaging of the retinal thickness are used. The fundus imaging is specifically employed to determine relative positional orientation on the retina when selecting and also when subsequently comparing specific regions of the retina. Although WO9730627 utilizes a fundus camera, relatively complicated optics required for a professional fundus camera are not used. The fundus illumination is not homogeneous since it is performed in one direction (through the upper or lower part of the pupil). Imaging acquisition is also limited since it is not symmetric relative to the fundus. Therefore, the fundus camera can be used only as an accessory for a retinal thickness analyzer apparatus. The apparatus according to WO9730627 is disadvantageous since it can not be used as a medical diagnostic fundus camera device.
Also recently, fundus cameras used (i.e. for imaging retinas) are being modified for digital operation which allows for computerized processing, displaying and storing retinal electronic images.
The treatment for macular edema is by laser photocoagulation. The decision if and in what exact location on the retina the treatment is required, is based on an assessment regarding the retinal thickening and the location of the thickened areas.
The assessment of retinal thickening according to one known method is by slit lamp biomicroscopy and/or stereo fundus photography. The performance of this method is often difficult, inaccurate, and of questionable reliability. The information gained by using fundus cameras to perform Fluorescein Angiography shows areas of leakage in the retina which are seemed to be, but not necessarily are, the areas of thickening which have to be treated.
It is therefore of utmost necessity for an apparatus which may correlate the visual information gained from the fundus images with the thickness information gained from the RTA.
The present invention relates to such an apparatus, which combines the properties of an RTA and a digital fundus camera, by integrating the optical systems of the two instruments into a single system, which allows for acquirement of retina image data simultaneously (or in close succession) with retina thickness data, allowing a complete correlation in the registration of the two sets of data.
SUMMARY OF THE INVENTION
The present invention relates to an apparatus for acquiring, analyzing and imaging retinal reflected data, comprising a combination of at least one digital fundus camera and a Retinal Thickness Analyzer, using common optical, electrical and mechanical components, wherein a common optical combiner unit is included in the components, allowing peripheral illumination and centered image acquisition of the eye fundus by a fundus-camera, together with a lateral slit-illumination for sensing the retinal thickness by an off-center slit-camera
Additionally to the optical combiner unit, the common components include at least one common component from the following; (a) a common objective lens; (b) a common reticulation element for providing a fixation target; (c) means for simultaneously focusing light beams of the RTA and of the fundus camera, going to and returning from the retina; (d) common processing and displaying means for displaying images of the retina structure, tailored from plurality of images acquired by the RTA and combined together according to images acquired by the fundus camera; (e) a common energy source; (f) common control panel and housing; (g) a common mechanical support for positioning the patient's face.
According to one variation of the apparatus, the common optical combiner unit is a removable dichroic mirror allowing acquisition of a high resolution slit image simultaneously with an average resolution fundus image, and the removable dichroic mirror is shifted out of the optical path for acquisition of a high resolution fundus image.
According to other variation of the apparatus, the common optical combiner unit is comprised of; (a) a central mirror for reflecting peripheral illumination onto the pupil and having an aperture at its center for transmitting the light returning from the retina to the fundus camera; (b) a first small mirror having an optical path disposed laterally off the center of the central mirror, for reflecting slit light onto the retina; (c) a second small mirror having an optical path disposed laterally off the center of the central mirror, for reflecting slit light returning from the retina to the slit camera; the two small mirrors are placed on two opposite sides of the central mirror. Preferably, the two small mirrors are integral parts of the central mirror, however, according to various considerations, they may also be positioned as separate parts, in front of the central mirror, or in the back of the central mirror, wherein the central mirror has two apertures conforming respectively with the optical paths of the small mirrors.
According to a preferred embodiment, the apparatus of the present invention has a first fundus camera for eye-fundus live image, and a second fundus camera for eye-fundus high resolution still image. Preferably, it further comprises a flash illumination source for acquiring still images.
In addition, the preferred embodiment of the apparatus comprise means for projecting a fixation target onto the examined eye of a patient, wherein the projecting means use at least in part the same optical path as the fundus camera. The embodiment also has a common focusing means for the slit light camera, the fundus camera and the fixation targe
Lowe Hauptman & Gilman & Berner LLP
Manuel George
Talia Technology Ltd.
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