Rectus Extraocular Muscle Paths and Staphylomata in High Myopia.

PURPOSE: To investigate the relationship between displacement of extraocular muscles (EOMs) and staphyloma in high myopia using magnetic resonance imaging (MRI).

DESIGN: Retrospective case-control study.

METHODS: Setting: Institutional study.

POPULATION: Twenty-nine highly myopic patients (46 eyes), 11 age-matched healthy control subjects (21 eyes), and 34 patients (66 eyes) with sagging eye syndrome.

PROCEDURES: MRI was analyzed for aspect ratio (AR) of the ocular cross section, locations of staphylomata and EOMs, and status of superior rectus to lateral rectus (SR-LR) band ligament.

MAIN OUTCOME MEASURES: Association between staphylomata with EOM paths and the LR-SR band.

RESULTS: Several associations of staphylomata were statistically significant (P < .05). Most staphylomata were superotemporal. Myopic patients with staphyloma had larger ARs in quasi-coronal images than in myopic subjects without staphyloma or normal controls. Compared to patients with high myopia without staphyloma and normal controls, when staphyloma was present, there was more inferior LR displacement, larger LR-globe angle, and larger SR-LR displacement angle than in myopic subjects without staphyloma. Staphyloma in the superotemporal quadrant was associated with greater SR-LR angle than in other quadrants. There were significantly more ruptures of SR-LR band ligament in highly myopic patients with staphyloma than in those without staphyloma.

CONCLUSIONS: Local staphylomata in high myopia reflect ocular asphericity and correlate with EOM paths. Myopic staphylomata are associated with inferior displacement of LR path and defect of the LR-SR band ligament.