The three-dimensional MRI for estimating the shape of eyeball of emmetropia and myopia

Abstract

Objective To investigate the morphologic characteristics of eyeballs in myopia with three-dimensional magnetic resonance imaging(3-D MRI). Methods The emmetropia (10 cases, 20 eyes), low myopia (10 cases, 20 eyes), medium myopia (10 cases, 20 eyes), high myopia (10 cases, 20 eyes) were enrolled. Patients which had eye diseases, history of ocular injury or surgery were excluded. In all cases the 3-D MRI were taken for the measurement of the sagittal, horizontal and vertical diameter of eyeball, eyeball volume and the ending points of eye muscle and optic nerve. Results The average value of sagittal, horizontal and vertical length of low myopia, medium myopia and high myopia group were much bigger than those of emmetropia group, especially the axial length. The average value of eyeball volume of myopia group was much bigger than that of emmetropia group. The eyeball, eye muscles and optic nerve were showed clearly in the 3-D MRI. The low and medium myopia group did not present obvious posterior staphyloma. Fifteen of 20 eyeballs in the high myopia group showed posterior staphyloma. Conclusion The sagittal, horizontal and vertical diameters and volume of the eyeball of low myopia, medium myopia and high myopia are significantly bigger than those of emmetropia. The 3-D MRI can show the eyeball shape, eye muscles and optic nerve clearly, which has the certain value in clinical work especially for eye surgery. Key words: Myopia; Diameter, eyeball; Volume, eyeball; Three-dimensional MRI