Photoreceptor Function and Structure in Retinal Areas With Intraretinal Hyperreflective Foci in Age-Related Macular...

To assess retinal light sensitivity in regions with intraretinal hyperreflective foci (IHRFs) in eyes with intermediate age-related macular degeneration (AMD) and examine the photoreceptor structure in these areas using adaptive optics scanning laser ophthalmoscopy (AOSLO) and optical coherence tomography (OCT).

A retrospective analysis was conducted on 82 eyes of 57 subjects (age: 76.4 ± 7.0 years) with intermediate AMD. IHRFs were identified in OCT B-scans. Drusen and subretinal drusenoid deposits (SDDs) were evaluated using multimodal imaging. Photoreceptor structure was assessed with AOSLO, and choroidal and retinal thicknesses were measured in areas with IHRFs. In 16 eyes, mesopic and scotopic light sensitivities were compared in regions with and without IHRFs but with similar SDD/drusen load in the same eye.

Retinal areas with IHRFs had significantly reduced mesopic (17.19 ± 5.68 dB vs. 18.49 ± 5.35 dB, P = 0.0029) and scotopic (8.39 ± 5.67 dB vs. 9.72 ± 6.28 dB, P = 0.0096) light sensitivity compared to areas without IHRFs. AOSLO revealed disrupted cone photoreceptor structure in IHRF regions. Choroidal thickness beneath areas with IHRFs was thinner than in those without IHRFs (196.71 ± 73.31 µm vs. 202.37 ± 70.64 µm, P = 0.0211). Retinal thickness in regions with IHRFs was not significantly different from those without IHRFs (320.40 ± 31.16 µm vs. 316.92 ± 26.32 µm, P = 0.3537).

IHRF presence is associated with localized reduced visual function and photoreceptor degeneration in intermediate AMD. Prospective studies are warranted to further investigate the mechanisms of photoreceptor and sensitivity loss in the context of IHRF.