Proposed classification of posterior staphylomas based on analyses of eye shape by three-dimensional magnetic resonance imaging and wide-field fundus imaging

Abstract

Purpose: To determine the incidence and types of posterior staphylomas in eyes with pathologic myopia by analyzing the entire eye shape by 3-dimensional (3D) magnetic resonance imaging (MRI).

Design: Observational, case series.

Participants: A total of 105 patients with pathologic myopia (spherical equivalent <-8.0 diopters or axial length ≥26.5 mm) were examined by 3D MRI and Optos (Optos, PLC, Dunfermline, Scotland).

Methods: Staphyloma was defined as an outpouching of the wall of the eye that had a radius of curvature less than the surrounding curvature of the wall of the eye. The presence and types of staphylomas were determined by the entire eye shape in 3D MRI scans. Fundus abnormalities suggesting the staphyloma border were analyzed in the fundus images, fundus autofluorescence images, and infrared images by Optos.

Main outcome measures: Incidence and types of posterior staphylomas, and the correlation between the type of staphyloma by MRI and the Optos images.

Results: A total of 198 eyes (105 patients) met the inclusion criteria of pathologic myopia (mean age, 64.3±11.5 years; mean axial length, 30.0±2.3 mm). Among 198 eyes, 98 (49.5%) had no staphylomas in 3D MRI scans and showed a barrel-shaped globe. The other 100 eyes (50.5%) had posterior staphyloma by 3D MRI. The most predominant type was wide, macular staphyloma (74% of eyes with staphyloma), followed by narrow, macular staphyloma (14% of eyes with staphyloma). In eyes with peripapillary and nasal staphylomas, the change of the curvature was slight and the eye had a nasally distorted shape. Optos images showed pigmentary abnormalities or abnormal reflectance along the staphyloma border. The patients with staphylomas were significantly older and had significantly worse visual function and more frequent chorioretinal changes than patients without staphyloma.

Conclusions: Three-dimensional MRI was useful in analyzing the shape of eyes with and without staphyloma. Even in elderly individuals with severe myopia, approximately one half of the patients did not show clear outpouching suggesting staphyloma. Correlating the MRI data to Optos images provided useful information on the relationship between the eye shape and the fundus appearances in the Optos images.