Histopathological Insights Into Choroidal Vascular Loss in Clinically Documented Cases of Age-Related Macular Degeneration

Abstract

IMPORTANCE-Age-related macular degeneration (AMD) is a multifactorial disease with genetic and environmental factors contributing to risk. Histopathologic changes underlying AMD are not fully understood, particularly the relationship between choriocapillaris (CC) dysfunction and phenotypic variability of this disease.OBJECTIVE-To examine histopathologic changes in the CC of eyes with clinically documented AMD. DESIGN, SETTING, AND PARTICIPANTS-The study was designed in 2011. Tissues were collected post mortem (2012)(2013)(2014)(2015)(2016), and histopathological images were obtained from participants enrolled in AMD studies since 1988. Clinical records and images were collected from participants as standard protocol. Eyes without AMD (n = 4) and eyes with early (n = 9), intermediate (n = 5), and advanced stages of AMD (geographic atrophy, n = 5; neovascular disease, n = 13) were evaluated. Choroidal vasculature was labeled using Ulex europaeus agglutinin lectin and examined using confocal microscopy.MAIN OUTCOMES AND MEASURES-A standardized classification system was applied to determine AMD stage. Ocular records and images were reviewed and histopathologic analyses performed. Viability of the choroidal vasculature was analyzed for each AMD stage.RESULTS-All participants were white. Fourteen were male, and 16 were female. The mean age was 90.5 years among AMD patients and 88.5 years among control participants. Submacular CC dropout without retinal pigment eipthelial (RPE) loss was observed in all cases with early stages of AMD. Higher vascular area loss for each AMD stage was observed compared with control participants: 20.5% in early AMD (95% CI, 11.2%-40.2%; P < .001), 12.5% in intermediate AMD (95% CI, 2.9%-21.4%; P = .01), 39.0% loss in GA (95% CI, 32.1%-45.4%; P < .001), and 38.2% loss in neovascular disease where RPE remained intact (95% CI, 27.7%-47.9%; P < .001).Hypercellular, apparent neovascular buds were adjacent to areas of CC loss in 22.2% of eyes with early AMD and 40% of eyes with intermediate AMD.CONCLUSIONS AND RELEVANCE-Retinal pigment epithelial atrophy preceded CC loss in geographic atrophy, but CC loss occurred in the absence of RPE atrophy in 2 of 9 eyes with earlystage AMD. Given the cross-sectional nature of this study and the small number of eyes evaluated, definitive conclusions regarding this progression cannot be determined with certainty. We speculate that neovascular buds may be a precursor to neovascular disease. Hypoxic RPE resulting from reduced blood supply might upregulate production of vascular endothelial growth factor, providing the stimulus for neovascular disease.Age-related macular degeneration (AMD) is a chronic and degenerative disease affecting the central part of the retina. It is the leading cause of irreversible visual loss in adults older than 60 years. 1,2 The etiology of AMD is multifactorial, and contributions of both genetic and environmental risk factors are well established [2][3][4] ; however, histopathologic changes Seddon et al.

Optical Coherence Tomography Features Preceding the Onset of Advanced Age-Related Macular Degeneration

“…29 Previous histologic studies have reported choriocapillaris loss underlying drusen, occurring very early in disease pathogenesis, 30,31 as well as reduced choroidal vessel density and diameter with advanced AMD. 32–34 Prior studies also reveal discordant results in evaluating the relationship between subfoveal choroidal thickness and advanced AMD.…”

The impact of oxidative stress and inflammation on RPE degeneration in non-neovascular AMD

“…In early AMD, Seddon et al recently found that choriocapillaris loss, using EC-binding lectin from Ulex europaeus (UEA-I) to distinguish live from ghost vessels, preceded RPE cell atrophy (Seddon et al, 2016). The Mullins laboratory, also using UEA-I, found that loss of choriocapillaris area and an increase in ghost vessels, correlated with increased drusen size and density, implicating a role for choriocapillaris dysfunction in drusenogenesis (Mullins et al, 2011).…”

Outer Retina and Choroidal Thickness in Intermediate Age-Related Macular Degeneration: Reticular Pseudodrusen Findings

“…Several studies have focused mainly on the level of the retina's outer layers, including the photoreceptors [4,5], the retinal pigment epithelium (RPE), Bruch's membrane (BM) [6][7][8][9], and the choroid [10,[11][12][13]. However, drusen [14][15][16][17], essential for the classification and monitoring of AMD [10,15], are the main alteration at the beginning of this degenerative process [18,19].…”