Characteristics of Anterior and Posterior Ocular Biometric Parameters in Nonamblyopic Myopic Anisometropia.

Objectives: This study aimed to quantify the differences in the anterior and posterior segment parameters between both eyes of individuals with nonamblyopic myopic anisometropia of ≥2 diopters (D).

Methods: This study enrolled 141 adults (mean age: 24.3±6.0 years; 48.3% men) with myopic anisometropia (binocular refractive difference of ≥2.0 D in spherical power). Bilateral measurements included refractive error (spherical equivalent, SE), mean keratometry, intraocular pressure, axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), peripapillary retinal nerve fiber layer (RNFL) thickness, optic nerve head (ONH) parameters, and macular thickness in Early Treatment Diabetic Retinopathy Study (ETDRS)-defined regions. Linear associations between variables and interocular differences in ocular parameters were statistically evaluated.

Results: The right eyes of the 68 men and 73 women enrolled in this study had significantly high myopia (P<0.05). The mean interocular difference in the SE was 2.72±0.93 D. The AL, ACD, and ACV were significantly greater for the more myopic eyes than for the contralateral eyes (all P<0.05). The CCT, ETDRS thickness, and ONH parameters (excluding average RNFL thickness) were lower for the more myopic eyes than for the contralateral eyes (all P<0.05). The superior quadrant RNFL thickness decreased with age (P<0.05). The refractive difference was significantly correlated with interocular differences in AL (r=0.735, P<0.001).

Conclusions: Interocular differences in anterior chamber parameters, macular thickness, and ONH structures were identified in adult patients with nonamblyopic myopic anisometropia. The more myopic eyes had thinner CCT, greater corneal curvatures, and specific ONH and macular layer alterations.