Radiation optic neuropathy after megavoltage external-beam irradiation: Analysis of time-dose factors
- Univ. of Florida College of Medicine, Gainesville, FL (United States); and others
To investigate the risk of radiation-induced optic neuropathy according to total radiotherapy dose and fraction size, based on both retrospective and prospectively collected data. Between October 1964 and May 1989, 215 optic nerves in 131 patients received fractionated external-beam irradiation during the treatment of primary extracranial head and neck tumors. All patients had a minimum of 3 years of ophthalmologic follow-up (range, 3 to 21 years). The clinical end point was visual acuity of 20/100 or worse as a result of optic nerve injury. Anterior ischemic optic neuropathy developed in five nerves (at mean and median times of 32 and 30 months, respectively, and a range of 2-4 years). Retrobulbar optic neuropathy developed in 12 nerves (at mean and median times of 47 and 28 months, respectively, and a range of 1-14 years). No injuries were observed in 106 optic nerves that received a total dose of <59 Gy. Among nerves that received doses of {ge} 60 Gy, the dose per fraction was more important than the total dose in producing optic neuropathy. The 15-year actuarial risk of optic compared with 47% when given in fraction sizes {ge}1.9 Gy. The data also suggest an increased risk of optic nerve injury with increasing age. As there is no effective treatment of radiation-induced optic neuropathy, efforts should be directed at its prevention by minimizing the total dose, paying attention to the dose per fraction to the nerve, and using reduced field techniques where appropriate to limit the volume of tissues that receive high-dose irradiation. 32 refs., 5 figs., 5 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 96056
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 30, Issue 4; Other Information: PBD: 15 Nov 1994
- Country of Publication:
- United States
- Language:
- English
Similar Records
Megavoltage external beam irradiation of craniopharyngiomas: Analysis of tumor control and morbidity
Visual Outcomes of Parapapillary Uveal Melanomas Following Proton Beam Therapy