Characteristic Thinning of Temporal Parafoveal Retinal Thickness in Patients With Intermittent Exotropia

To quantitatively compare the temporal parafoveal retinal thickness between intermittent exotropia (IXT) and healthy controls using optical coherence tomography, exploring the relationship between retinal structural changes and retinal correspondence.

Cross-sectional study.

Twenty basic type IXT with an exodeviation angle of 35 prism diopters (PD) were compared with 20 age-matched healthy controls. All enrolled participants underwent a comprehensive ophthalmic evaluation, including optical coherence tomography, axial length, prism alternate cover test, retinal correspondence, and stereoacuity. The retinal thickness at parafoveal position corresponding to the exodeviation angle of 25 PD, 30 PD, 35 PD, 40 PD, and 45 PD were measured. Interocular symmetries of the retinal thickness were analyzed according to ocular laterality or dominance in the IXT group. Comparative analysis of temporal parafoveal retinal thickness was conducted between the IXT group and the normal control group. According to the retinal correspondence, IXT patients were divided into the anomalous retinal correspondence (ARC) group and the non-ARC group, and further comparative analysis was conducted on retinal thickness between the two groups.

The temporal parafoveal retinal thickness was symmetrical between the eyes in IXT patients without significant interocular difference (P > .05). However, the retinal thickness at the corresponding parafoveal position of the exodeviation angle (35 PD) was significantly reduced in IXT patients (P < .0001), which was thinner in the nondominant eyes of the ARC group (P = .007).

Patients with IXT showed characteristic thinning of the retinal thickness in the temporal parafoveal region corresponding to the exodeviation angle, presenting a structure similar to a shallow "pseudo-fovea." The relationship between structural changes and correspondence in the retina needs to be further investigated.