Accommodation in humans with juvenile macular degeneration

Abstract

Accommodation, or the change in refractive power of the eye to focus objects at different distances, is driven by many stimuli including defocus blur, the awareness of target distance or proximal cues, and through the vergence crosslink (convergence accommodation). The effectiveness of defocus blur as an accommodative stimulus is decreased in normally-sighted subjects as visual acuity is experimentally reduced and as the target is imaged at increasing eccentricities from the fovea. Since subjects with central retinal abnormalities have reduced visual acuity 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 subjects with juvenile macular degeneration (JMD) and of three normally-sighted controls were measured. The effectiveness of defocus blur in stimulating accommodation varied across the subjects and was related to visual acuity, with those subjects having worse acuity showing less accurate 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, those subjects who did not modulate accommodative response with changing defocus blur cues showed the most accurate accommodation under binocular viewing. In contrast, those subjects who did change accommodative response with changing defocus blur cues showed the most accurate accommodation under monocular viewing.

Accommodation and pupil responses to random-dot stereograms

“… 32 Similarly, the effectiveness of defocus blur as an accommodative stimulus should also decrease with eccentricity as acuity declines (and effective depth of focus increases). 33 Consistent with this prediction, White and Wick 34 found that accommodation response to defocus blur was reduced in juvenile macular degeneration (Stargardt's disease). The degree of reduction was generally greatest in those with the poorest acuity.…”

Accommodative anomalies in children

“…These are all different stimuli to accommodation, with 'Blur' of an object having the greatest impact as stimuli, though independent of visual acuity. [ 10 ]…”

Accommodative Response in Patients with Central Field Loss: A Matched Case-Control Study

“…Patients with visual impairment (VI) (e.g., age related macular degeneration, diabetic retinopathy, glaucoma, and corneal opacity) prominently have reduced VA that could lead to unreliable AR [ 32 , 33 ]. Some of these patients do not visit the clinic with complaints that are suggestive of accommodative difficulties [ 34 ]. One explanation is that these patients could depend on cues other than or in addition to defocus blur to effectively drive accommodation [ 34 ].…”

“…Some of these patients do not visit the clinic with complaints that are suggestive of accommodative difficulties [ 34 ]. One explanation is that these patients could depend on cues other than or in addition to defocus blur to effectively drive accommodation [ 34 ].…”

“…Previously, some cross-sectional studies investigated AR in patients with VI at certain points of age but reported conflicting results [ 34 , 35 , 36 ]. White and Wick investigated the AR of patients with juvenile macular degenerations [ 34 ], with SRI servo-controlled punctuation infrared optometer and ranging in age from 19 to 34 years.…”