Reduction of retinal vessel density in non-exudative macular neovascularization: a retrospective study

Abstract

Purpose: The purpose of this study is to identify predictive activation biomarkers in retinal microvascular characteristics of non-exudative macular neovascularization (MNV) and avoid delayed treatment or overtreatment of subclinical MNV. The main objective is to contribute to the international debate on a new understanding of the role of retinal vessel features in the pathogenesis and progression of non-exudative MNV and age-related macular degeneration (AMD). A discussion on revising-related clinical protocols is presented.

Methods: In this retrospective study, the authors included eyes with non-exudative MNV, eyes with exudative AMD, and normal eyes of age-matched healthy subjects. The parameters were obtained by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA).

Results: In total, 21 eyes with exudative AMD, 21 eyes with non-exudative MNV, and 20 eyes of 20 age-matched healthy subjects without retinal pathology were included. Vessel density (VD) of the deep vascular complex (DVC) in eyes with non-exudative MNV was significantly greater than that in eyes with exudative AMD (p = 0.002), while for superficial vascular plexus (SVP) metrics, no VD differences among sectors were observed between eyes with non-exudative MNV and eyes with exudative AMD.

Conclusion: The reduction in retinal vessel density, especially in the DVC, seems to be involved in or be accompanied by non-exudative MNV activation and should be closely monitored during follow-up visits in order to ensure prompt anti-angiogenic therapy. A discussion on applicable clinical protocols is presented aiming to contribute to new insights into ophthalmology service development which is directed to this specific type of patient and diagnosis.

Keywords: age-related macular degeneration; non-exudative macular neovascularization; optical coherence tomography; retinal blood flow; retinal image.

Figure 1

Box plot showing retinal vascular indexes in exudative AMD patients, non-exudative MNV patients, and healthy controls. #, p < 0.05; ##, p < 0.01; and ###, p < 0.001.

Figure 2

Optical coherence tomography angiography 3 × 3 mm scan of exudative AMD eyes (A–D), non-exudative MNV eyes (E–H), and healthy eyes (I–L). The OCTA map shows the contour (inner yellow ring) of the FAZ and a 300 μm wide area (limited by the outer yellow ring) where the flow density (FD-300) was calculated (A,E,I). En face OCTA and OCTA B-scan with flow marked in red (B,F,J). En face OCTA angiograms with color-coded VD (color bar: warmer colors representing the higher VD) of the retinal vascular plexuses: SVP (C,J,K), DVC (D,H,L).