The evaluation of the macular and optic nerve head microvasculature in amblyopic and non-amblyopic patients with constant exotropia in comparison to healthy controls

Abstract

Objective

To evaluate the retinal microvascular changes in strabismic amblyopia and compare them to the strabismic cases without amblyopia and controls.

Design

Cross-sectional study.

Participants

Three groups of patients, including 25 amblyopic cases with exotropia (XT), 25 constant XT cases without amblyopia, and 25 healthy subjects as controls, are included in the study. Both eyes of the included participants are evaluated.

Methods

All the patients underwent a thorough ophthalmic examination, BCVA assessment, and macular and optic nerve head OCTA with the AngioVue™ Imaging System.

Main Outcome Measures

The vascular density (VD) of various layers (Deep and superficial capillary plexus (DCP and SCP) in different regions of the macula, optic nerve head, and FAZ area were evaluated as the target variables.

Results

42 females and 33 males with a mean age of 32.2 (95%CI:29.8-34.6) entered our study. The median exotropia in both groups was 35 PD. The parafoveal DCP VD was significantly lower in both eyes of amblyopic cases than in controls (53.56 and 52.31 vs. 56.13%, p:0.021, <0.001). The parafoveal SCP VD was only lower in the dominant eye of the amblyopic cases than in the controls (50.53 vs. 53.54%, p:0.002). The foveal and peripapillary VD showed no significant difference between the groups. The FAZ area was significantly larger in amblyopic eyes than the fellow eyes (0.250 vs. 0.194 mm², p:0.025) and correlated with worse BCVA (Correlation Coefficient: 0.358, p: 0.011).

Conclusions

The amblyopia could be accompanied by a lower parafoveal DCP VD and a larger FAZ area in strabismic amblyopia.