Three-Dimensional Eye Shape, Myopic Maculopathy, and Visual Acuity: The Zhongshan Ophthalmic Center-Brien Holden Vision Institute High Myopia Cohort Study

Abstract

Purpose: To investigate the relationship among eye shape, myopic maculopathy, and visual acuity in highly myopic eyes using 3-dimensional (3D) magnetic resonance imaging (MRI).

Design: Observational case series.

Participants: The study included 190 eyes of 95 participants with bilateral high myopia from the Zhongshan Ophthalmic Center-Brien Holden Vision Institute High Myopia Cohort Study, with spherical power ≤-6.00 diopters (D) in both eyes.

Methods: The participants underwent best-corrected visual acuity (BCVA), fundus photography, cycloplegic refraction, and ocular biometry. Posterior staphyloma was identified with 3D MRI, and ocular shapes were categorized into spheroidal, ellipsoidal, conical, nasally distorted, temporally distorted, and barrel shapes according to the inferior view from T2-weighted 3D MRI (Achieva 3.0T; Philips Medical Systems, Best, the Netherlands). Myopic maculopathy was graded as C0 to C4 according to the International Photographic Classification and Grading System using fundus photography. The statistical significance of the differences in distribution of myopic maculopathy and BCVA in eyes with different ocular shapes was determined using Pearson's chi-square tests.

Main outcome measures: Distributions of myopic maculopathy and BCVA in relation to different eye shapes.

Results: The mean spherical equivalent and axial length were -11.74±4.10 D and 28.18±1.73 mm in the right eyes, respectively. The same ocular shapes were observed in both eyes in 69 participants (72.6%). The predominant shape was spheroidal (53.7%), followed by nasally distorted and conical types (both 14.7%). C2 and above myopic maculopathy was observed in all barrel-shaped eyes, in 75% temporally distorted eyes, and in 71.4% nasally distorted and conical eyes. In eyes with posterior staphyloma (n = 22), 18 (81.8%) had C2 and above myopic maculopathy compared with 40 eyes (54.8%) without posterior staphyloma (n = 73). Eyes with temporal and nasal distortion, and eyes with staphyloma were more likely to have BCVA <20/40.

Conclusions: Not all highly myopic eyes are deformed. Spheroid was the predominant ocular shape in this series of young patients with high myopia bilaterally. Barrel-shaped and temporally distorted eyes present significant myopic maculopathy, whereas eyes with posterior staphyloma display more severe chorioretinal atrophy. Eyes of more deformed shapes tend to have more severe myopic maculopathy and worse BCVA.