Purpose
High myopia is often associated with elongation and distortion of the globe, and at greater risk of developing pathologic changes. Lack of topographic and morphologic assessments hinders the understanding towards the natural history and mechanism in its development. We evaluated the fundus changes in high myopia by analyzing the eye shapes using three-dimensional (3D) magnetic resonance imaging (MRI) in a case series study.
Methods
A total of 95 patients with high myopia (spherical power ≤ -6.00D) in both eyes underwent a series of ophthalmic examinations. Eye shapes were categorized into spherical, ellipsoidal, cylindrical, nasal-distorted, temporal-distorted and barrel-shaped according to the inferior view from T2-weighted 3D MRI images (Achieva 3.0T, Philips Medical Systems, Best, the Netherlands); posterior staphyloma was also identified. Fundus lesions were determined using two 45° photos centered at macula and optic nerve by dilated fundus photography (Canon Inc., Tokyo, Japan). The distributions of various fundus characteristics in different eye shape categories were analyzed using one-way ANOVA and Mann-Whitney Wilcoxon tests.
Results
The participants consisted 48.4% females, had a mean age of 32.0±14.0 years old, spherical equivalence of -11.00±7.44D and axial length (AL) of 28.18±1.73mm. The same ocular shapes between the two eyes were observed in 72.6% of the patients. The most predominant shape in the right eye was spherical (54.3%), followed by nasal-distorted (16.0%) and cylindrical (14.9%). Barrel-shaped eyes had the longest AL and most outstanding fundus changes. Diffuse chorioretinal atrophy and larger peripapillary atrophy (PPA) were more frequently observed in barrel-shaped (100.0%, 4.7±2.7 disc area, DA) and nasally distorted (73.3%, 2.5±2.5 DA) eyes; While diffuse (77.3%) and patchy (22.7%) chorioretinal atrophy, as well as fundus staphyloma (72.7%) were more common in eyes with posterior staphyloma (n=22) determined by 3D MRI.
Conclusions
Barrel-shaped eyes present most significant vision-threatening conditions, while eyes with posterior staphyloma display more severe chorioretinal atrophy. Our findings suggest different topographic and morphologic patterns may be involved in the development of high myopia.