Abstract
To analyze the longitudinal spatial distribution characteristics of intraretinal hyperreflective foci (IHRF) in eyes with intermediate age-related macular degeneration (iAMD).
The optical coherence tomography (OCT) data was collected from the Amish Eye Study, for all patients with evidence of iAMD and IHRF at baseline, who completed a 24 month (M24) follow up visit. Early Treatment Diabetic Retinopathy Study (ETDRS) rings were placed on the enface scans from all volume scans showing IHRF, and the frequency and the density of IHRF was measured in the central subfield (CSF; 1 mm circle), the 1-3 mm ring (parafoveal region) and the 3-6 mm ring (perifoveal region). The distance of all IHRF lesions from the foveal center was measured.
Forty-nine eyes (40 subjects) had iAMD and IHRF at baseline and M24. 23 eyes (46.9%) showed progression to late AMD. The frequency of IHRF was greatest in the parafoveal ring, although the density was highest in the CSF. IHRF number and density numerically increased in all regions at M24, though the increase was significant only in the perifoveal region. Although regression analysis did not show a relationship between baseline IHRF distribution and risk for progression to late AMD at 2 years, eyes that developed late AMD at M24 tended to show a more eccentric distribution of IHRF over time.
IHRF do not distribute evenly across the macula in eyes with iAMD, with a higher density centrally, but greater frequency parafoveally. IHRF tend to distribute more peripherally over time, however, among eyes that progress to late AMD. These observations may provide new insights into the pathophysiology of these lesions.