Pediatric vision screening using binocular retinal birefringence scanning

摘要

We have developed a specialized form of retinal birefringence scanning (RBS), in which a small spot of polarized light is scanned in a circle on the retina, and the returning light is measured for the changes in polarization cuased by the pattern of birefringent fibers that radiate from the fovea. Binocular RBS (BRBS) detects fixation of both eyes simultaneously and thus screens for strabismus, one of the risk factors of amblyopia. We have also developed a technique to automatically detect when the eye is in focus without measuring refractive error. This focus detector utilizes a bull's eye photodetector optically conjugate to a point fixation source. Reflected light is focused back to the point source by the optical system of the eye and if the subject focuses on the fixation source, the returning light will be focused on the detector. We have constructed a hand-held prototype combining BRBS and focus detection measurements in one quick (<0.5 second) and accurate (theoretically detecting ±1° of misalignment) measurement. Here we present our data of BRBS and focus detection signals in a number of normal and amblyopic subjects, demonstrating that this approach can reliably and effectively identify children at risk for amblyopia.