Topographic Analyses of Shape of Eyes with Pathologic Myopia by High-Resolution Three-Dimensional Magnetic Resonance Imaging

Objective: To analyze the topography of human eyes with pathologic myopia by high-resolution magnetic resonance imaging (MRI) with volume rendering of the acquired images. Design: Observational case series. Participants: Eighty-six eyes of 44 patients with high myopia (refractive error >=-8.00 diopters [D] or axial length >26.5 mm) were studied. Forty emmetropic eyes were examined as controls. Methods: The participants were examined with an MRI scanner (Signa HDxt 1.5T, GE Healthcare, Waukesha, WI), and T(2)-weighted cubes were obtained. Volume renderings of the images from high-resolution 3-dimensional (3D) data were done by computer workstation. The margins of globes were then identified semiautomatically by the signal intensity, and the tissues outside the globes were removed. Main Outcome Measures: The 3D topographic characteristic of the globes and the distribution of the 4 distinct shapes of globes according to the symmetry and the radius of curvature of the contour of the posterior segment: the barrel, cylindric, nasally distorted, and temporally distorted types. Results: In 69.8% of the patients with bilateral high myopia, both eyes had the same ocular shape. The most protruded part of the globe existed along the central sagittal axis in 78.3% of eyes and was slightly inferior to the central axis in the remaining eyes. In 38 of 68 eyes (55.9%) with bilateral pathologic myopia, multiple protrusions were observed. The eyes with 2 protrusions were subdivided into those with nasal protrusions and those with temporal protrusions. The eyes with 3 protrusions were subdivided into nasal, temporal superior, and temporal inferior protrusions. The eyes with visual field defects that could not be explained by myopic fundus lesions significantly more frequently had a temporally distorted shape. Eyes with >= 2 protrusions had myopic chorioretinal atrophy significantly more frequently than eyes with <= 1 protrusion. Conclusions: Our results demonstrate that it is possible to obtain a complete topographic image of human eyes by high-resolution MRI with volume-rendering techniques. The results showed that there are different ocular shapes in eyes with pathologic myopia, and that the difference in the ocular shape is correlated with the development of vision-threatening conditions in eyes with pathologic myopia. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2011; 118: 1626-1637 (C) 2011 by the American Academy of Ophthalmology.