Macular Microvasculature and Associated Retinal Layer Thickness in Pediatric Amblyopia: Magnification-Corrected Analyses

Abstract

Purpose: The purpose of this study was to characterize macular microvasculature and structural retinal layers using magnification-corrected optical coherence tomography angiography (OCTA) images in children with amblyopia.

Methods: This prospective cross-sectional study included 22 children with unilateral amblyopia (4-11 years of age) receiving spectral-domain OCTA. Vessel densities in foveal and parafoveal regions of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were measured in amblyopic and fellow eyes using a customized image analysis program correcting the scale of retinal image with axial length. Iowa Reference Algorithms (Iowa Institute for Biomedical Imaging) were used to measure mean thickness values of 10 intra-retinal layers rescaled for image size correction.

Results: Foveal and parafoveal vessel densities in amblyopic eyes were lower than that of the fellow eyes in the SCP (fovea: P = 0.006 and parafovea: P = 0.003) and the DCP (P = 0.024 and P = 0.025, respectively). Amblyopic eyes had significantly smaller foveal avascular zone (FAZ) area than fellow eyes (P < 0.001). There were significant differences in retinal layer thickness between paired eyes, particularly in the inner retina in both foveal and parafoveal regions; retinal nerve fiber layer (RNFL) (P = 0.024 and P = 0.095, respectively), ganglion cell layer (P < 0.001 and P = 0.008), inner plexiform layer (IPL; P = 0.12 and P = 0.037), inner nuclear layer (P = 0.005 and P = 0.005), and outer plexiform layer (OPL; P = 0.02 and P = 0.057), except in the foveal IPL, the parafoveal RNFL, and OPL.

Conclusions: Unilateral amblyopic eyes demonstrate reduced macular vessel density and thicker inner retinal layers compared with fellow eyes even after correcting for image magnification. Changes in macular microvasculature and structural layers may offer valuable insights in the development of amblyopia.

Figure 1.

Typical spectral-domain optical coherence tomography angiography (OCTA) images. Example of macular (nominal scan area = 3 × 3 mm) superficial and deep capillary plexus scans from an amblyopic eye (axial length of 21.89 mm) and the fellow eye (axial length of 23.45 mm). The yellow circles demarcate analysis regions (2.2 mm) corrected for axial length.

Figure 2.

Diagram showing regions of interest. The fovea was defined by a circle 0.5 mm in diameter and the global parafovea by an annulus 0.5 to 1.1 mm in radius centered on the fovea. The parafoveal region was subdivided into superior, inferior, temporal, and nasal quadrants.