Instrument for MTF Measurements of Cataractous Eyes

Abstract

With approximately 1.5 million cataract surgeries performed each year in the United States, there is great need for a non-invasive ophthalmic instrument that measures objectively the inability of a cataractous eye to produce clear images. We describe here the construction and operation of a new instrument which meets this need. Called the Ocular Resolution Analyzer (ORA), the instrument projects a fine line on a patient's retina, records the blurred retinal line image, and quantifies the extent of blurring by computing the Modulation Transfer Function. In clinical tests on cataract patients, increased blurring measured by the ORA has been shown to correlate with other indicators of cataract development: 1) increasing lens opacification as observed with a slit lamp,1 2) loss of visual acuity,2 3) loss of contrast sensitivity, and 4) increased glare sensitivity.3