Junichi Kiryu

Background: Structural changes of the choroid, such as choroidal thickening, have been indicated in amblyopic eyes with hyperopic anisometropia as compared to fellow or healthy eyes. The purpose of the present study was to investigate choroidal vascular density (CVD) in children with unilateral hyperopic amblyopia.Methods: This study included 88 eyes of 44 patients with unilateral amblyopia due to hyperopic anisometropia with or without strabismus and 29 eyes of 29 age-matched normal controls. The CVD of Haller’s layer was quantified from en-face images constructed by 3-dimensional swept-source optical coherence tomography images flattened relative to Bruch’s membrane. The analysis area was a 3 × 3-mm square of macula after magnification correction. Relationships between CVD and other parameters [best-corrected visual acuity (BCVA), refractive error and subfoveal choroidal thickness (SFCT)] were investigated, and CVDs were compared between amblyopic, fellow, and normal control eyes.Results: Mean CVD was 59.11 ± 0.66% in amblyopic eyes, 59.23 ± 0.81% in fellow eyes, and 59.29 ± 0.74% in normal control eyes. CVD showed a significant positive relationship with SFCT (p = 0.004), but no relationships with other parameters. No significant differences in CVD were evident among amblyopic, fellow, and normal control eyes after adjusting for SFCT (p = 0.502).Conclusions: CVD was unrelated to BCVA, and CVD did not differ significantly among amblyopic, fellow and normal control eyes. These results suggest that the local CVD of Haller’s layer is unaffected in unilateral hyperopic amblyopic eyes.

To investigate the area of foveal avascular zone (FAZ) and macular vessel density (VD) after correction for magnification error in unilateral amblyopia using optical coherence tomography angiography (OCTA). Participants comprised 15 patients with unilateral amblyopia due to anisometropia with or without strabismus (mean age, 9.8 ± 3.4 years; range, 6–17 years). OCTA images were obtained by using spectral-domain OCT with angiography software. The OCTA scanning protocol used was 3 × 3-mm volume scan centered on the fovea. OCTA images were corrected for magnification errors using individual axial length (AL), and an adjusted 2.3 × 2.3-mm square was derived as a region of interest. The FAZ area and VD in both superficial capillary plexus (SCP) and deep capillary plexus (DCP) layers, foveal minimum thickness (FMT) were assessed using built-in OCTA software and ImageJ software (NIH, Bethesda, MD). LogMAR in the amblyopic eyes was significantly poorer than that of the fellow eye (p < 0.001). AL was significantly shorter in the amblyopic eye than in the fellow eye (p < 0.001). FAZ area of SCP in amblyopic eyes was significantly smaller than that of fellow eyes (p < 0.001). No significant differences were seen in FAZ area of DCP, VD of SCP, VD of DCP, and FMT between amblyopic and fellow eyes (p = 0.07, 0.43, 0.55, and 0.25, respectively). Our present study after magnification error correction found smaller FAZ area of SCP in the amblyopic eye compared with the fellow eyes, but there was no significant difference in the macular VD between the amblyopic and fellow eyes.

Recent studies using optical coherence tomography (OCT) have indicated that choroidal thickness (CT) in the anisometropic amblyopic eye is thicker than that of the fellow and normal control eyes. However, it has not yet been established as to how amblyopia affects the choroid thickening. The purpose of the present study was to investigate the effect of amblyopia treatment on macular CT in eyes with anisometropic amblyopia using swept-source OCT. Thirteen patients (mean age: 6.2 ± 2.4 years) with hypermetropic anisometropic amblyopia were included in this study. Visual acuity (VA), axial length (AL), and CT were measured at the enrollment visit and at the final visit, after at least 6 months of treatment. CT measurements were corrected for magnification error and were automatically analyzed using built-in software and divided into three macular regions (subfoveal choroidal thickness (SFCT), center 1 mm, and center 6 mm). A one-way analysis of covariance using AL as a covariate was performed to determine whether CT in amblyopic eyes changed after amblyopia treatment. The average observation period was 22.2 ± 11.0 months. After treatment, VA (logMAR) improvement in the amblyopic eyes was 0.41 ± 0.19 (p < 0.001). SFCT, center 1 mm CT, and center 6 mm CT were significantly thicker in the amblyopic eyes compared with the fellow eyes both before and after treatment (p < 0.05 for all comparisons). There were no significant changes in SFCT, center 1 mm CT, or center 6 mm CT before and after treatment in the amblyopic (p = 0.25, 0.21, and 0.84, respectively) and fellow (p = 0.75, 0.84, and 0.91, respectively) eyes. The correlation between changes in logMAR versus changes in CT after treatment was not significant. Although VA in amblyopic eyes was significantly improved after treatment, the choroid thickening of anisometropic amblyopic eyes persisted, and there was no significant change found in the CT after the treatment. Our findings suggest that thickening of the CT in amblyopia is not directly related to visual dysfunction.

To investigate macular retinal and choroidal thickness in amblyopic eyes compared to that in fellow and normal eyes using swept-source optical coherence tomography (SS-OCT). This study examined 31 patients with hyperopic anisometropic amblyopia (6.9 ± 3.8 years, mean ± standard deviation), 15 patients with strabismic amblyopia without anisometropia (7.9 ± 4.2 years), and 24 age-matched controls (7.8 ± 3.3 years). Retinal and choroidal thickness was measured by 3D scans using SS-OCT. A 6-mm area around the fovea was automatically analyzed using the Early Treatment Diabetic Retinopathy Study map. The thickness from SS-OCT was corrected for magnification error using individual axial length, spherical refraction, cylinder refraction, and corneal radius. Retinal thickness was divided into the macular retinal nerve fiber layer (mRNFL), ganglion cell layer + inner plexiform layer (GCL+IPL), ganglion cell complex (GCC), and the inner limiting membrane to the retinal pigment epithelium (ILM-RPE) thickness. Retinal and choroidal thickness was compared among amblyopic, fellow, and normal eyes. In both amblyopia groups, there was no significant difference in the mRNFL, GCL+IPL, and GCC thicknesses among the amblyopic, fellow, and control eyes. In the anisometropic amblyopia group, choroidal thickness (subfovea, center 1 mm, nasal and inferior of the inner ring, nasal of the outer ring, and center 6 mm) of amblyopic eyes were significantly greater than that of fellow and normal eyes. In contrast, none of the choroidal thicknesses were significantly different among the investigated eyes in the strabismic amblyopia group. We found no significant difference in inner retinal thickness in patients with unilateral amblyopia. Although there were significant differences in choroidal thickness with hyperopic anisometropic amblyopia, there was no significant difference for the strabismic amblyopia. The discrepancy in choroidal thickness between the two types of amblyopia may be due to both differences in ocular size and underlying mechanism.