Holographic Phase Compensation Techniques Applied to Human Cataracts

Abstract

The inability to observe intraocular pathology behind cataracts is a particularly acute problem to the ophthalmologist from the standpoints of assessment and continuing diagnosis. Moreover, when immediate surgery is required, precise location of the damage and assessment of the pathological necessities are seriously hampered. We have succeeded in demonstrating that image degradation by a cataract is due primarily to random phase aberrations within and on the surface of the cataract. We show that the cataract may be considered to be a quiescent, random phase-distorting medium. The technique of phase aberration balancing is used to cancel the cataract's aberrating power. Our procedure consists of forming a hologram of the phase aberrations. This hologram is then used as a filter, in conjunction with the cataract itself, to correct what would otherwise be highly distorted imagery. In our experiments, using excised cataracts, the average visual acuity of the cataracts before filtering was 20/200, whereas the average acuity after correction was 20/15.