First Author: A.Papayannis ITALY
Co Author(s): F. Romano F. Stringa E. Tsamis P. Stanga
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To investigate Ultrahigh Speed Swept Source optical coherence tomography Angiography (UHS SS-OCT-A) vascular density alterations in eyes of patients affected by non-exudative age-related macular degeneration (NEAMD).
The study was designed as an observational, cross-sectional case series. A total of 14 eyes from seven normal subjects and 20 eyes from ten patients with NEAMD were consecutively recruited from November 2015 to February 2017.
Topcon Triton UHS SS-OCT-A commercially available system was used to perform volumetric optical coherence tomography angiography in normal subjects and patients with non-exudative AMD presenting geographic atrophy (GA) or drusen. All the currently acknowledged retinal and choroidal neurovascular layers were evaluated, specifically: superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC). The mean vascular density was automatically estimated with the use of the analysis software Imagenet 6 version 1.19. A mean value of vascular density was calculated as the percentage of hyperreflective material, corresponding to vascular flow, for each of the nine macular sectors of the ETDRS grid. In the end, a quantitative comparison of retinal and CC vascular densities in normal subjects and in patients with a clinical diagnosis of NEAMD was carried out to assess the extent of vascular flow impairment in the retinal plexuses and CC.
The normal group included four male and three female subjects (mean age = 49.8 ± 7.4 years old), whereas NEAMD group comprised six male and four female patients (mean age = 59.6 ± 4.2 years old). Best corrected visual acuity was significantly worse in diseased eyes (p = .02). The 20 eyes with nonexudative AMD showed on UHS SS-OCT-A a marked retinal and CC mean vascular density reduction within the macular areas characterized by GA or Drusen (p < .0001). In detail, eyes with NEAMD showed a vascular density of 43.8 ± 11.5 in SCP of affected areas (vs. 60.0 ± 6.1 of normal eyes), 18.5 ± 10.8 in DCP (vs. 33.9 ± 5.8) and 60.9 ± 11.6 in CC (vs. 93.5 ± 1.4).
Ultrahigh Speed Swept Source OCT-A is capable to noninvasively visualize alterations in the retinal and CC neurovascular layers of patients affected by non-exudative AMD. This makes it a promising and reliable tool to assess and follow-up these patients. Despite we acknowledge the fact that vascular density analysis can result abnormal in areas above large drusen due to projection artifacts, all the patients additionally presented signs of vascular rarefaction extending over the retinal areas adjacent to them.