The Impacts of Episcleral Plaque Brachytherapy on Ocular Motility.

Background

To investigate the effect of various factors on ocular motility disturbance after episcleral plaque brachytherapy with Ruthenium 106 (106Ru).

Methods

Twenty consecutive patients who underwent plaque brachytherapy for all types of intraocular tumors were included in this interventional prospective case series. Ruthenium-106 was used with a mean total dose of 93.2 ± 21.2 Gy toward the tumor apex. Full orthoptic examinations were performed before and after the surgery.

Results

The average follow-up time was 6 months (range: 4-9 months). Two (10%) out of 20 patients developed exotropia. The mean age of patients without strabismus was higher than the patients with strabismus (49.8 ± 10.7 years compared to 23 ± 4.2 years, respectively) (p = .011). Strabismus was observed in the patients who had tumors with larger apical diameters (7.6 ± 2 mm compared to 4.1 ± 0.9 mm, respectively) (p = .021). The mean radiation dose to the tumor base in the group with strabismus was higher than the group without motility disturbance (1046.5 ± 604.1 Gy compared to 384.3 ± 175.3, respectively) (p = .021). Most tumors were located in the inferotemporal fundus (30%), followed by supratemporal location (25%), supranasal (10%), and macular region (10%). A higher percentage of patients with postoperative strabismus underwent muscle manipulation compared to the patients who did not develop this complication (100% compared to 38.9%).

Conclusion

Manipulation of the extraocular muscles, high doses of radiation, and low vision could cause strabismus after episcleral plaque brachytherapy.