Purpose:
To characterize the morphology, prevalence, and topography of SDD, an extracellular, cholesterol-containing lesion that is a potential histological correlate of reticular (pseudo-) drusen [1], and BlinD, a diffusely distributed, cholesterol-rich, lesion that is specific to AMD (Figure).
Methods:
Donor eyes with median death-to-preservation = 2:40 hr were post-fixed in osmium tannic acid paraphenylenediamine and prepared for macula-wide high-resolution sections [2]. Study eyes, without exudative changes, exhibited pigmentary disturbances ≥2A (scale modified from [3]) AND either drusen or continuous basal laminar deposits. Lesion morphologies and annotated thicknesses of chorioretinal layers were recorded at standard locations [2] in 2 horizontally oriented sections that together included the fovea and nasal, temporal, and superior perifovea (0.8-3 mm eccentricity).
Results:
In these 21 eyes of 19 Caucasian donors (13 female, 6 male, 83.5 ± 7.7 yr), SDD had two essential formations: isolated domes with caps of outer segment-like material and confluent dollops punctuated by tufts of RPE apical processes, both associated with photoreceptor perturbation. 18/21 eyes (85.7%) had measurable SDD and BlinD, respectively. SDD was thick (median, 9.4 µm) and present in more perifoveal (28.7%) than foveal (10.2%) sampling locations, BlinD was thinner (median, 2.1 µm) and present in more foveal (36.6%) than perifoveal (16.5%) locations.
Conclusions:
SDD and BlinD prevalence in AMD eyes are both high. SDD’s organized morphology, resembling lesions in adult vitelliform macular degeneration [4], plus its topography and impact on surrounding photoreceptors imply specific processes of biogenesis. SDD’s predominantly perifoveal, and BlinD’s predominantly foveal, locations suggest relationships with rod and cone topography, respectively. Perhaps differentiable aspects of rod and cone physiology, such as cholesterol homeostasis, contribute to lesion biogenesis, as well as complement activation and other processes. References [1] Zweifel. Ophthalmology. 2010;117:303. [2] Curcio. IOVS 2011;52:3943. [3] Vogt. Exp Eye Res. 2011;93:413. [4] Arnold. Eye. 2003;17:717.
Keywords: age-related macular degeneration • drusen • photoreceptors