Abstract
Purpose: :
To assess if AMD patients are aware of binocular central visual field defects as they present for low vision rehabilitation (lvr).
Methods: :
153 consecutive AMD patients in initial lvr evaluation were asked: 1. If they were able to see any blind spots or defects in their field of vision and 2. If they had any evidence or experiences that led them to believe that they had defects in their field of vision. They then had vision assessed by: binocular central visual field testing for dense and relative scotomas using the California Central Visual Field Test; binocular reading performance evaluated with SK Read and MN Read charts; and VA with ETDRS chart at 1 meter. Scotomas within 2.5 degrees of fixation had mean diameter noted.
Results: :
Patient age median/range was 84/61 - 98 years with 67% female. All patients had AMD with 48% dry and 52% wet (76% of wet had received anti VEGF treatment). Duration of AMD symptoms was mean/range 7/0.5 to 23 years. Visual acuity median/range was 20/253 and 20/40 to HM. Only 12% did not demonstrate a binocular scotoma and 66% had a binocular dense scotoma. Scotoma diameter mean/range was relative 12.1/0 to 30 and dense 8.6/0 to 30 degrees. 75/134 (56%) with binocular scotomas were totally unaware of their presence even with dense scotomas measuring up to 30 degrees diameter. 2/134 (1.5%) could fleetingly see a defect in their visual field upon waking. 59/134 (44%) related experiences of things "disappearing" on them. The mean/range scotoma diameter of those unaware vs some awareness of their scotomas was comparable - and 7.2/0-30 vs 5.9/0-30 degrees for dense and 13.8/2-30 vs 10.6/1-30 degrees for relative. The SK Read mean error rate for the unaware group was 5.4 errors per block and the aware group was 3.3 errors per block. The SK Read mean error rate for the no scotoma group was 1.0 errors per block. There was no significant relationship of scotoma awareness with age, acuity, scotoma size, density, or duration of onset. Awareness of scotoma was associated with less errors on the SK Read test. (p<.01)
Conclusions: :
On initial evaluation 88% of AMD patients referred for lvr demonstrated binocular scotomas near fixation and more than half were totally unaware of their presence. Presence of scotomas decreased reading accuracy but some awareness of the scotomas had a tendency to improve accuracy. The value of rehabilitation programs aimed at increasing patient awareness of their scotomas may be supported by this evidence.
Keywords: low vision • reading • age-related macular degeneration