Factors Associated with Occurrence of Radiation-induced Optic Neuropathy at “Safe” Radiation Dosage

ABSTRACT

Background: Radiation-induced optic neuropathy (RION) is a rare, and often visually devastating, complication of radiation therapy (RT) near the anterior visual pathways. Methods: A retrospective case series of patients who developed RION at a tertiary medical center, followed by a case-control study comparing RION cases with matched controls who received RT. Results: Thirteen patients (18 eyes) with RION were identified. Radiation modalities included external beam photon radiation, whole brain radiation, stereotactic radiosurgery, proton beam, and unknown. Most patients received doses below published “safe” thresholds (<55 Gy; <8–10 Gy for stereotactic radiosurgery). There was no statistically significant difference in prevalence of vasculopathic factors between cases and controls; on subgroup analysis in three patients who received surprisingly low radiation doses, smoking (p=0.05) and hypertension (p=0.02) appeared more prevalent. Conclusion: RION can occur at doses below published “safe” thresholds and with different RT modalities. Smoking and hypertension might be risk factors for RION.

Keywords:

• Radiation complications
• radiation-induced optic neuropathy
• radiation toxicity

ACKNOWLEDGMENTS

Dr. Michelle Alonso-Basanta has had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

FUNDING

This work was supported by Research to Prevent Blindness. Statistical analysis for this project was supported by the National Institutes of Health Grant 2-P30-EY01583-26 from the National Eye Institute. The funding sources had no role in the collection, analysis, and interpretation of data, nor in the writing of the manuscript or the decision to submit the manuscript for publication.

DECLARATION OF INTEREST

The authors do not have any relevant financial or personal conflict of interest to disclose. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This work was supported by Research to Prevent Blindness. Statistical analysis for this project was supported by the National Institutes of Health Grant 2-P30-EY01583-26 from the National Eye Institute. The funding sources had no role in the collection, analysis, and interpretation of data, nor in the writing of the manuscript or the decision to submit the manuscript for publication.