Optical Coherence Tomography-Angiography in Geographic Atrophy

Abstract

Geographic atrophy (GA) represents the non-exudative late stage of age-related macular degeneration and constitutes a leading cause of legal blindness in the developed world. It is characterized by areas of loss of outer retinal layers including photoreceptors, degeneration of the retinal pigment epithelium, and rarefication of the choriocapillaris. As all three layers are functionally connected, the precise temporal sequence and relative contribution of these layers towards the development and progression of GA is unclear. The advent of optical coherence tomography angiography (OCT-A) has allowed for three-dimensional visualization of retinal blood flow. Using OCT-A, recent studies have demonstrated that choriocapillaris flow alterations are particularly associated with the development of GA, exceed atrophy boundaries spatially, and are a prognostic factor for future GA progression. Furthermore, OCT-A may be helpful to differentiate GA from mimicking diseases. Evidence for a potential protective effect of specific forms of choroidal neovascularization in the context of GA has been reported. This article aims to give a comprehensive review of the current literature concerning the application of OCT-A in GA, and summarizes the opportunities and limitations with regard to pathophysiologic considerations, differential diagnosis, study design, and patient assessment.

Modeling of atrophy size trajectories: variable transformation, prediction and age-of-onset estimation

“…High blood pressure is shown to be associated with lower choroidal blood flow and disturbed vascular homeostasis [ 30 ]. Since perfusion deficits in the choriocapillaris, the innermost layer of the choroid, are associated with future GA progression [ 31 ], an associate between hypertension and increased GA progression appears biologically plausible. Regarding the association of hypercholesterinemia and decreased GA progression, the biological plausibility remains elusive.…”

Clinical application and development of OCT and OCTA in fundus diseases

“…Cicinelli et al [31] used OCTA to observe hyaline warts and choroidal capillaries, and concluded that OCTA can detect insufficient choroidal vascular perfusion to identify hyaline warts and diagnose choroidal capillary dysfunction. Geographic atrophy (GA) is a typical characteristic change in late stage dry AMD [32]. OCTA shows a significant decrease in capillary signal within the GA lesion, while the signal in the surrounding area is normal.…”

Correlative study on retinal microvascular changes and sex hormones in male patients with central serous chorioretinopathy

“…Each B scan repeated the OCT angiogram at the same position at least twice. Furthermore, OCTA was performed with the Supervisory Control And Data Acquisition (SSADA) algorithm [10] with a working wavelength of 840 nm and 7000 axial scans per second. After scanning the retinal and choroidal vessels, OCTA can be divided into four layers: the superficial and deep retinal plexus, the outer retina and the choriocapillaris.…”

“…Optical coherence tomography angiography (OCTA) is a newly developed technique for fundus examination. In contrast with traditional examinations, this technique does not require the injection of contrast agents; it also has included a wider array of indicators, a better safety profile and can provide quantitative data relating to ocular blood flow [8][9][10]. In this study, we investigated the relationship between sex hormone levels and OCTA parameters in male CSC patients in attempt to identify factors involved in the pathogenesis of CSC.…”