Study links high-dose proton therapy to potential neurotrophic keratitis risk

Proton therapy for cephalic extraocular tumors does not significantly impact corneal sensitivity 6 months after treatment, as long as radiation doses to the cornea remain low, according to a study. However, a dose per fraction above 2 GyRBE may reduce corneal sensitivity.

The study included 43 patients (85 eyes) who underwent high-energy proton therapy, assessing their corneal sensitivity before and approximately 6 months after treatment.

Using the Cochet-Bonnet esthesiometer, researchers found no significant changes in corneal sensitivity, tear break-up time, or superficial punctate keratitis. The study reported mean maximal radiation doses of 10.7 GyRBE to the cornea and 42.0 GyRBE to its sensory innervation structures. Although overall corneal sensitivity remained stable, a dose per fraction exceeding 2 GyRBE was linked to a significant sensitivity decrease (P = 0.033).

The findings suggest that corneal damage risk is low when radiation doses are minimized. However, given previous reports of neurotrophic keratitis at corneal doses above 50 GyRBE, further studies are needed to clarify the long-term effects of high-dose proton therapy on corneal health.

Reference
Lebrun F, Thariat J, Marty PA, et al. Prospective Study of Corneal Sensitivity in Patients Treated With Proton Therapy for Extraocular Tumors. Cornea. 2024;doi: 10.1097/ICO.0000000000003781. Epub ahead of print. PMID: 39661121.