Evaluating the Volume of Eyes With Pathologic Myopia Using 3D MRI.

PURPOSE: To determine the volume of eyes and its relationship to the shape and the presence of posterior staphylomas in patients with high myopia (HM).

METHODS

We studied 370 eyes of 199 patients with HM (refractive error >8.00 diopters [D] or an axial length ≥26.5 mm) and 44 eyes of 35 control patients without HM (refractive error from -7.50 to +2.50 D). Magnetic resonance imaging (MRI) of the ocular orbit was used to measure the volume of the eye using three-dimensional (3D) MRI. Reconstructed 3D images of eye were classified according to symmetry and steepness of the posterior curvature.

RESULTS

The mean volume was 12.42 ± 2.40 mL of the 370 HM eyes and 9.67 ± 1.41 mL of the 44 non-HM eyes. Thus, the volume of the HM eyes was 1.3 times larger than the mean volume of the non-HM eyes. The mean volume of the eye was significantly smaller in the cylindrically shaped and larger in barrel-shaped eyes than the eyes with other shapes. The mean eye volume in the HM eyes with a posterior staphyloma was not significantly different from that of HM eyes without a posterior staphyloma.

CONCLUSIONS

The volume of HM eyes is larger than non-HM eyes and is associated with steepness of posterior curvature but not with the presence of a posterior staphyloma, suggesting that local outward protrusion of the posterior eye wall is not directly caused by global expansion of eyes and should be monitored specifically in HM eyes.