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

Abstract

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.

Analysis of Macular Retinal Thickness and Microvascular System Changes in Children with Monocular Hyperopic Anisometropia and Severe Amblyopia

“…Further, OCTA's application on retinal microvascular system research has aroused the interest of multiple scholars. In related research on the retina of patients with amblyopia, Nishikawa et al [ 5 ] scanned the macular area of OCTA in 22 children with monocular amblyopia. It was seen that the vessel density of the central fovea and accessory central fovea in amblyopic eyes was lower than that in the healthy contralateral eyes, and the central foveal avascular area in amblyopic eyes was significantly smaller than that in the contralateral eyes.…”

Macular Retinal Microvasculature of Hyperopia, Emmetropia, and Myopia in Children

“…Both eyes of each participant were included for ophthalmologic examinations: best-corrected visual acuity (BCVA) assessment (Snellen chart), cycloplegic optometry (1% cyclopentolate was instilled 30 and 25 min before optometry/autorefraction), comprehensive optometry, intraocular pressure measurement (non-contact tonometer, RT-2100; Nidek Co., Ltd., Gamagori, Aichi, Japan), AL measurement (IOL-Master 500; Carl Zeiss Meditec, Dublin, CA, United States), fundus photography (AFC-210, Nidek Co., Ltd., Gamagori, Aichi, Japan), and slit-lamp examination. Subjects with amblyopia or squint ( 24 ), ocular diseases other than refractive error, a history of ocular trauma, a history of ocular laser or surgery, BCVA < 6/6, astigmatism ≥ 1.00 diopters (D), wearing orthokeratology lenses, or systemic disease were excluded from participation.…”

All retinas are not created equal: Fovea‐to‐macula thickness ratio and foveal microvasculature in healthy young children

“…The Littman and Bennett formulae were used to calculate the true image size of the OCTA scans 17,32,33 . In short, the relationship between the measured OCTA image diameter (D m ) and the true diameter of the fundus (D t ) was computed using the equation:where p × q was the overall image magnification factor, p was the magnification factor of the imaging system and q was that of the eye.…”

“…However, a recent study has shown that amblyopic eyes have thicker inner retinal layers and reduced vessel density when compared with non-amblyopic fellow eyes, suggesting that thicker foveae are not necessarily associated with increased vessel density. 17 Foveal thickness alone does not give information about the structure of the foveal pit, which is a marker for good foveal development and advantageous for visual acuity. 18,19 The centrifugal displacement of inner retinal layers forming the foveal pit reduces the light scattering at neuronal structures and blood vessels and allows a nearly direct illumination of the photoreceptors.…”

“…This is unsurprising, as thinner foveae should have less need for inner retinal vasculature. However, a recent study has shown that amblyopic eyes have thicker inner retinal layers and reduced vessel density when compared with non‐amblyopic fellow eyes, suggesting that thicker foveae are not necessarily associated with increased vessel density 17 …”