The analysis of the dimensional measurement in high myopia by MRI / 眼科

ABSTRACT

Objective To discuss the expansion model of the eyeball and investigate the morphologic characteristics of high-my- opic eyeball through the dimensional measurement in high-myopia and emmetropia by MRI. Design Case controll study. Participants Thirty-two emmetropes (60 eyes) and 33 high myopes (60 eyes) were enrolled, without eye diseases and history of ocular surgery or in- jury. Methods 60 high-myopic eyes and 60 emmetropic eyes were measured with MRI (I.5T,PHILIPS) to get the data of three inner ocular dimensions, intraocular volume and the volume of different parts. Main Outcome Measures Three dimensions and volumes of eyeballs. Results The average value of axial (28.16?2.80 mm), horizontal (22.87+1.23 mm) and vertical length (23.40?0.99 ram) of high-myopic eyes were much bigger than those of emmetropic eyes(P=0.000), especially the axial length( with difference of 5.38 mm); The axial length was correlated with refractive error (0.36 mm/D,r~2=0.88, P=0.000). The average value of the whole ocular volume (7. 46?0.89 ml) and vitreous volume(6.90?0.8 ml) of the high myopic eyes were bigger than those of emmetropic eyes(P=0.000), while ante- rior segment volume and lens volume were about the same as that of emmetropic eyes (P=0.220, P=0.630). Conclusions The three di- mensions of high-myopic eyes were significantly longer than that of emmetropic eyes. In high myopes, the increased vitreous volume lead to the increase of the whole ocular volume. There may be two models in the ocular expansion of high myopia global expansion and axial elongation expansion. More serious refractive error cause more obvious expansion in axial elongation.