ACCOMMODATION IN HUMANS WITH JUVENILE MACULAR DEGENERATION

Accommodation, or the change in refractive power of the eye to focus o bjects at different distances, is driven by many stimuli including def ocus blur, the awareness of target distance or proximal cues, and thro ugh the vergence crosslink (convergence accommodation), The effectiven ess of defocus blur as an accommodative stimulus is decreased in norma lly-sighted subjects as visual acuity is experimentally reduced and as the target is imaged at increasing eccentricities from the fovea, Sin ce subjects with central retinal abnormalities have reduced visual acu ity and typically fixate eccentrically, one would predict that defocus blur would not be an effective accommodative stimulus for them, Using an infrared optometer, steady-state accommodative responses of six su bjects with juvenile macular degeneration (JMD) and of three normally- sighted controls were measured, The effectiveness of defocus blur in s timulating accommodation varied across the subjects and was related to visual acuity, with those subjects having worse acuity showing less a ccurate accommodative responses, When provided with additional cues to accommodative demand (i.e. proximal and/or binocular cues), subjects with JMD showed more accurate accommodative responses, In general, tho se subjects who did not modulate accommodative response with changing defocus blur cues showed the most accurate accommodation under binocul ar viewing, In contrast, those subjects who did change accommodative r esponse with changing defocus blur cues showed the most accurate accom modation under monocular viewing.