Radiation optic neuropathy after megavoltage external-beam irradiation: analysis of time-dose factors

Int J Radiat Oncol Biol Phys. 1994 Nov 15;30(4):755-63. doi: 10.1016/0360-3016(94)90346-8.


Purpose: 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.

Methods and materials: 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.

Results: 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 > or = 60 Gy, the dose per fraction was more important than the total dose in producing optic neuropathy. The 15-year actuarial risk of optic neuropathy after doses of > or = 60 Gy was 11% when treatment was administered in fraction sizes of < 1.9 Gy, compared with 47% when given in fraction sizes of > or = 1.9 Gy. The data also suggest an increased risk of optic nerve injury with increasing age.

Conclusion: 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.

Publication types

  • Clinical Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • Dose-Response Relationship, Radiation
  • Eye / radiation effects
  • Female
  • Head and Neck Neoplasms / radiotherapy
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Optic Nerve / radiation effects*
  • Optic Nerve Diseases / etiology*
  • Prospective Studies
  • Radiation Injuries / etiology*
  • Radiation Protection
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy, High-Energy / adverse effects*
  • Retrospective Studies
  • Time Factors
  • Vision Disorders / etiology