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Ocular motility changes after subtenon carboplatin chemotherapy for retinoblastoma
Alan Mulvihill1, Andrew Budning, Venita Jay
1Department of Ophthalmology and Division of Hematology-Oncology, Department of Pediatrics, The Hospital for Sick Children and University of Toronto, Toronto, Ontario.
Background:
Focal subtenon carboplatin injections have recently been used as a presumably toxicity-free adjunct to systemic chemotherapy for intraocular retinoblastoma.
Objective:
To report our clinical experience with abnormal ocular motility in patients treated with subtenon carboplatin chemotherapy.
Methods:
We noted abnormal ocular motility in 10 consecutive patients with retinoblastoma who had received subtenon carboplatin. During ocular manipulation under general anesthesia, we assessed their eyes by forced duction testing, comparing ocular motility after tumor control with ocular motility at diagnosis. Eyes subsequently enucleated because of treatment failure (n = 4) were examined histologically.
Results:
Limitation of ocular motility was detected in all 12 eyes of 10 patients treated for intraocular retinoblastoma with 1 to 6 injections of subtenon carboplatin as part of multimodality therapy. Histopathological examination revealed many lipophages in the periorbital fat surrounding the optic nerve in 1 eye, indicative of phagocytosis of previously existing fat cells and suggesting prior fat necrosis. The enucleations were technically difficult and hazardous for globe rupture because of extensive orbital soft tissue adhesions.
Conclusions:
Subtenon carboplatin chemotherapy is associated with significant fibrosis of orbital soft tissues, leading to mechanical restriction of eye movements and making subsequent enucleation difficult. Subtenon carboplatin is not free of toxicity, and its use is best restricted to specific indications.