Features of macular retinal and choroidal vessels and structure in patients with hyperopic anisometropic amblyopia

Objective  To quantitatively analyze macular retinal and choroidal vascular and structural parameters in patients with hyperopic anisometropic amblyopia using swept-source optical coherence tomography angiography (SS-OCTA).

Methods  A self-controlled study was conducted. Sixty patients with hyperopic anisometropic amblyopia (120 eyes) diagnosed at Henan Eye Hospital from January 2022 to June 2023 were included. Among them, 60 hyperopic amblyopic eyes were set as a hyperopic amblyopia group, and 60 contralateral emmetropic eyes were used as a control group. In order to deeply explore the effects of different hyperopia degrees and amblyopia severity on the structure and blood flow of the maculal retinal and choroidal vascular and structural parameters, this study further divided hyperopic anisometropic amblyopia into a mild to moderate hyperopic amblyopia group (28 eyes) and a severe hyperopic amblyopia group. All eyes were scanned using SS-OCTA, and the following parameters were measured including superficial capillary plexus vascular density (SCPVD), deep capillary plexus vascular density (DCPVD), choroidal thickness (ChT), choroidal vascular volume (CVV), choroidal vascularity index (CVI), and fovea avascular area (FAZ) area. This study was conducted in accordance with the Declaration of Helsinki. The research protocol was approved by the Ethics Committee of Henan Eye Hospital (No. HNEECKY-2022[10]). All participants were informed of the nature and potential consequences of the study and provided written informed consent. For minors, informed consent was signed by their legal guardians.

Results  The overall SCPVD, DCPVD, CVV, and ChT in the macula area in the hyperopic amblyopic group were higher than those in the fellow eye group, and the CVI was lower than that in the fellow eye group, with statistically significant differences ( t=8.439, 7.008, 14.068, 29.857, -29.943; all P<0.001). The SCPVD, DCPVD, CVV, and ChT in the inner ring nasal side, the inner ring inferior, the outer ring superior side, the outer ring temporal side, and the outer ring inferior in the hyperopic amblyopic group were higher than those in the fellow eye group, and the CVI was lower than that in the fellow eye group (all P<0.05). The CVV, ChT above the inner ring were higher in the hyperopic amblyopic group than in the fellow eye group, and the SCPVD, CVV, and ChT at the inner ring temporal side and the outer ring nasal side were higher than that in the fellow eye group. The CVI in different regions was lower than that in the fellow eye group (all P<0.05). The FAZ areas in the hyperopic amblyopic group and fellow eye group were (0.34±0.07) and (0.33±0.06)mm ^2, respectively, with no significant difference ( t=1.649, P>0.05). The overall SCPVD, DCPVD, and ChT in the severe hyperopic amblyopia group were higher and the CVI was lower than those in the mild to moderate hyperopic amblyopia group, with statistically significant differences ( t=2.213, 2.166, 6.115, -2.076; all P<0.05). SCPVD and DCPVD in the outer ring temporal side and outer ring inferior side in severe hyperopic amblyopia group were higher than those in mild to moderate hyperopic amblyopia group, and the differences were statistically significant (SCPVD: t=2.051, 2.045; both P<0.05; DCPVD: t=2.212, 2.264; both P<0.05). The ChT in the inner ring nasal side, inner ring temporal side, inner ring inferior side, outer ring temporal side, and outer ring inferior side in the severe hyperopic amblyopia group were higher than those in the mild to moderate hyperopic amblyopia group, and the differences were statistically significant ( t=2.124, 2.902, 3.081, 2.562, 2.641; all P<0.05).

Conclusions  In patients with hyperopic anisometropic amblyopia, compared with contralateral eyes, there are vascular and structural abnormalities in the macula area and choroid of the affected eye, which are mainly manifested by increased vessel density volume, ChT thickening, reduced CVI, and the degree of abnormality is related to the severity of hyperopic anisometropic amblyopia.