Association of Optical Coherence Tomography Angiography Metrics With Detection of Impaired Macular Microvasculature and Decreased Vision in Amblyopic Eyes

Abstract

IMPORTANCE Microvascular abnormalities in amblyopia are becoming evident with high-resolution imaging, such as optical coherence tomography angiography (OCT-A); however, to our knowledge, the clinical significance and use of these findings are unknown.OBJECTIVE To assess changes in quantitative OCT-A metrics in amblyopic eyes and explore their association with visual acuity in children. DESIGN, SETTING, AND PARTICIPANTSThis population-based nested case-control study included children aged 6 to 8 years who were consecutively recruited between January 2016 and July 2017 from the population-based Hong Kong Children Eye Study (HKCES) at the Chinese University of Hong Kong Eye Centre. All participants underwent OCT-A with a swept-source OCT and detailed ophthalmic investigations. Macular microvasculature of the superficial capillary plexus was quantified by a customized automated image analysis program. A multivariable linear regression was conducted to evaluate the differences in OCT-A metrics between amblyopic and nonamblyopic eyes after adjustment for all known confounders. Data analysis was conducted from September to November 2018. MAIN OUTCOMES AND MEASURESDifferences in OCT-A metric (foveal avascular zone [FAZ]) area, FAZ circularity, vessel density, vessel diameter index, and fractal dimension between amblyopic and nonamblyopic eyes. RESULTS There were 30 participants with amblyopia (mean [SD] age, 7.57 [1.2] years; 16 girls [53.3%]) and 1045 controls (mean [SD] age, 7.65 [1.0] years; 580 girls [55.5%]) in this cohort.Compared with control eyes, amblyopic eyes had decreased FAZ circularity (−0.058; 95% CI, −0.096 to −0.021, P = .002), decreased fractal dimension (−0.014; 95% CI, −0.024 to −0.003; P = .01), and increased vessel diameter index (0.002; 95% CI, 0.002 to 0.003; P < .001). A difference was not identified between FAZ area and vessel density. LogMAR visual acuity was associated with FAZ circularity (sβ, −0.133; P < .001) and vessel diameter index (sβ, 0.097; P = .001) but not with vessel density nor FAZ area. CONCLUSIONS AND RELEVANCEThe results of this population-based study in children supports the presence of macular microvascular abnormalities in amblyopic eyes. Such changes as measured by OCT-A metrics are associated with visual acuity, inferring retinal involvement in the development of amblyopia and suggesting a potential role of quantitative OCT-A metrics in the diagnosis and recognition of amblyopia.

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

“…Some recent studies on amblyopia paid attention to magnification effect; 4,10-12,30-32 however, most of them merely used statistical adjustment to adjust the effects of AL along with other clinical factors. 4,10,12,30,32 In the current study, AL was significantly shorter in amblyopic eyes compared with the nonamblyopic fellow eyes, emphasizing the importance of AL adjustment in identifying disease-specific abnormalities in the retinal structure. Therefore, we corrected the image magnification of scans using ImageJ when analyzing FAZ parameters and vessel densities.…”

“…Several previous reports have found reduced SCP and DCP vessel densities in amblyopic eyes, [7][8][9]32,33 but another found only reduced SCP vessel density 10 and two others reported no changes. 11,12 Of these previous studies, one corrected for magnification effects using a built-in software, 11 three adjusted AL statistically, 10,12,32 and the others did not conduct or explicitly mention magnification correction. [7][8][9]33 One study that corrected for lateral scaling reported negative results, but the sample size was relatively small (n = 15).…”

“…The images were resized to originals and then the FAZ area and circularity index were measured similar to previous studies. 12,[21][22][23] Regarding the vessel density analysis, the following processing was performed, with the foveal region being defined as a circular area with a radius of 0.5 mm and the parafoveal region as an annulus with a radius of 0.5 to 1.1 mm from the foveal center (Fig. 2).…”

“…Amblyopia was once considered a disorder of the visual cortex and lateral geniculate nucleus without structural abnormalities in the retina; however, since the advent of optical coherence tomography (OCT) and OCT angiography (OCTA), several studies have reported possible structural changes compared with normal eyes, including differences in macular thickness, [1][2][3][4] retinal nerve fiber layer (RNFL), [1][2][3] and individual retinal layers, 5,6 and macular capillary vascular structure, including the foveal avascular zone (FAZ) area. [7][8][9][10][11][12] Although these findings may provide novel insights to our understanding of amblyopia, they are now called into question. Specifically, measurements performed with OCT/OCTA have inherent errors when the scale of retinal image is not corrected for axial length (AL) of each eye.…”

Comparison of Choroidal Thickness Measurements between Spectral-domain Optical Coherence Tomography and Swept-source Optical Coherence Tomography in Children

“…Data for this analysis were derived from the Hong Kong Children Eye Study (HKCES), a population-based cohort study of eye conditions in children aged 6 to 8 years. [19][20][21][22][23] Study subjects were recruited consecutively from November to December 2015. All underwent the comprehensive ophthalmic examination, physical examination and standardised questionnaires at the Chinese University of Hong Kong Eye Centre.…”