Quantitative analyses of high-resolution 3D MR images of highly myopic eyes to determine their shapes.

PURPOSE

We analyzed the symmetry and pointedness of the posterior segment of highly myopic eyes.

METHODS

We studied 234 eyes of 117 patients with bilateral high myopia (refractive error ≤-8.00 diopters [D]) and 40 eyes of 20 patients with emmetropia (refractive error between -1.0 and +1.0 D). Volume renderings of high-resolution magnetic resonance (MR) images were performed to obtain 3D images of the eye. To analyze the symmetry and pointedness of the posterior surface, a software was developed to measure the area and angle of a fan-shaped segment formed by selected points on the MR images.

RESULTS

All of the emmetropic eyes were symmetrical in the horizontal and sagittal planes with no deformity. In highly myopic eyes, the shape was symmetrical in the horizontal plane in 146 eyes (62.4%) and in the sagittal plane in 162 (69.2%). The shape of the posterior pole was pointed (angle of fan-shaped segment <150°) in 45.7% and blunted (angle ≥150°) in 54.3% of highly myopic eyes. The most common shape was symmetrical in the horizontal and sagittal planes, and the posterior surface was blunt. The shape of the two eyes of the same individual was the same in 61 of 117 patients (52.1%). In 56 patients whose two eyes had different shapes, the most frequent pattern was a difference in the pointedness (51.8%).

CONCLUSIONS

Quantitative assessments of the shape of eyes were useful in determining the pattern of eye shape deformity specific to pathologic myopia.