A test battery to monitor visual function in blind volunteers for retinal cell transplantation

Purpose. To perform accurate monitoi ing of visual function and retinal physiology in subjects with minimal or no light percep ion participating in a pilot project of fetal retinal cell transplantation. Clinically used me'hods to describe very low levels of vision {hand motions or worse) are very crude. Methods. Tests were designed to reproducibly measure visual function in small step iicrements. Test methods included, in order of administration, and in rough order of vis on level required to complete thenr dark-adapted detection of ganzi'eld and hand-held Gras. PS22 strobe flashes with calibrated attenuations; naming projection of a penlight from a Mandardized set of directions; full field and focal ERG responses; retinal landmark mapfing, penmetry, and acuity measurement with a Rodenstock SLO. Goidmann V/4e perirnMry; visual acuity (Lighthouse chart) and contrast sensitivity (Pelli-Robson chart). Six sibjects with end-stage retinal degeneration from retinitis pigmentosa have been tested to date, one subject has useful vision in the fellow eye; in all other subjects careful pre-op 'estmg determined the worse eye. which received the graft. Results. Flash detection was the mosi sensitive measure of change, and the only test that could be completed by all patients. ERG responses were indistinguishable from noise in all patients. Projection ard SLO testing in three patients were complicated by poor fixation and/or uncontrollable nystagmus. Charts were useful only for the one patient's fellow eye with useful vision. Testing of both eyes on every visit proved very important, since fluctuations of absolute sensitivities were up to 10 dB between visits, but typically highly symmetric between a si eject's eyes. Conclusion. Standardized vision test protocols with fine calibrated steps a re extremely important, not just tor this study but also for natural his'ory studies and or any other future treatment trial of retinal degenerations Such test batteries can hi ild on existing equipment and test standards, such as those set for clinical trials or adoptee by professional societies such as ISCEV.