Purpose
In order to evaluate the effectiveness of emerging treatments for geographic atrophy, responsive metrics of visual function are required. Histological, psychophysical and questionnaire data indicate reduced rod function in age-related maculopathy (ARM) and geographic atrophy (GA). In this study we use the new test of dark-adapted microperimetry on a cohort of patients with ARM and GA to determine the effectiveness of this test on identifying areas of retinal abnormality.
Methods
20 patients with ARM or GA were recruited. Conventional and dark-adapted microperimetry were performed on a modified microperimeter (MP-1S, Nidek Technologies, Italy). Perimetry maps were registered with autofluorescence images (obtained using Spectralis, Heidelberg Engineering, Germany; superimposed using Navis software (Nidek Technologies, Italy)). Areas of abnormality on the autofluorescence image were identified by an ophthalmologist masked to microperimetry results.
Results
On average, more points were not seen at the highest intensity on dark-adapted than conventional microperimetry (mean number of points missed: conventional: 4.45, dark-adapted: 12.2; matched pairs t-test, p<0.01). Dark-adapted sensitivity was poorer over areas of abnormality identified on autofluorescence imaging than over healthy retina (p<0.001). A significant relationship was identified between abnormal autofluorescence and missed points on dark-adapted microperimetry (Cochran-Mantel-Haenszel test, stratified by patient, p<0.0001).
Conclusions
Performance on dark-adapted microperimetry was poorer than performance on conventional (mesopic) microperimetry testing in our patients with ARM and GA. Failure to detect a test point on dark-adapted microperimetry was significantly associated with the corresponding retinal location being identified as unhealthy on autofluorescence imaging. These results suggest that dark-adapted microperimetry may be a useful outcome measure in studies of geographic atrophy.
Keywords: 642 perimetry •
412 age-related macular degeneration •
758 visual fields