Radiation Optic Neuropathy After Whole-Brain Radiation Therapy

Radiation-Induced Retinopathy and Optic Neuropathy after Radiation Therapy for Brain, Head, and Neck Tumors: A Systematic Review

Background: Patients with brain, head, and neck tumors experience a decline in their quality of life due to radiation retinopathy and optic neuropathy. Little is known about the dose–response relationship and patient characteristics. We aimed to systematically review the prevalence of radiation retinopathy and optic neuropathy. Method: The primary outcome was the pooled prevalence of radiation retinopathy and optic neuropathy. The secondary outcome included the effect of the total radiation dose prescribed for the tumor according to the patient’s characteristics. Furthermore, we aimed to evaluate the radiation dose parameters for organs at risk of radiation retinopathy and optic neuropathy. Results: The pooled prevalence was 3.8%. No retinopathy was reported for the tumor’s prescribed dose of <50 Gy. Optic neuropathy was more prevalent for a prescribed dose of >50 Gy than <50 Gy. We observed a higher prevalence rate for retinopathy (6.0%) than optic neuropathy (2.0%). Insufficient data on the dose for organs at risk were reported. Conclusion: The prevalence of radiation retinopathy was higher compared to optic neuropathy. This review emphasizes the need for future studies considering retinopathy and optic neuropathy as primary objective parameters.

Radiation-induced optic neuropathy: a review

Radiation is a commonly used treatment modality for head and neck as well as CNS tumours, both benign and malignant. As newer oncology treatments such as immunotherapies allow for longer survival, complications from radiation therapy are becoming more common. Radiation-induced optic neuropathy is a feared complication due to rapid onset and potential for severe and bilateral vision loss. Careful monitoring of high-risk patients and early recognition are crucial for initiating treatment to prevent severe vision loss due to a narrow therapeutic window. This review discusses presentation, aetiology, recent advances in diagnosis using innovative MRI techniques and best practice treatment options based on the most recent evidence-based medicine.

Treatment and prophylaxis of radiation optic neuropathy: A systematic review and meta-analysis

PURPOSE

Radiation optic neuropathy (RON) generally follows radiation therapy that exceed 50 Gy to the visual axis and occurs within three years of therapy. Currently, there are no universally accepted treatments or prophylaxis for RON. The review aimed to examine the efficacy of all treatments and prophylaxis for RON.

METHODS

MEDLINE, Embase, the Cochrane Library, and gray literature were searched to December 2020. Studies on treatment(s) and/or prophylaxis of RON were included. Results were meta-analyzed using a random-effects model. Primary outcomes included the proportions of patients who experienced improvement, no change, or worsening of visual acuity (VA) for each treatment. Secondary outcome was the incidence of RON for studies on prophylaxis.

RESULTS

Overall, 50 studies (n = 5397) were included. Meta-analysis (n = 1752) showed significantly lower incidence of RON in patients who underwent intravitreal anti-VEGF prophylaxis compared to control (RR 0.64, 95%CI [0.48, 0.86]) for uveal melanoma. Intravitreal anti-VEGF injections (n = 68), hyperbaric oxygen therapy alone (n = 14), and pentoxifylline (n = 5) resulted in improved or stable vision ≤1 logMAR in 54.5%, 42.9%, and 40.0% of patients, respectively. Systemic corticosteroids (n = 82), anticoagulants (n = 12), and systemic bevacizumab (n = 7) showed improved or stable vision ≤1 logMAR in 17.1%, 33.3%, and 14.3% of patients, respectively. Overall risk of bias was low, but evidence was limited to retrospective studies.

CONCLUSION

Intravitreal anti-VEGF injections reduced incidence of RON in irradiated uveal melanoma patients. Systemic corticosteroids, systemic bevacizumab, and warfarin alone are likely ineffective treatments. Early hyperbaric oxygen therapy and intravitreal anti-VEGF injections were most effective among those investigated and require further investigation.

Necrosis of the optic nerve and chiasm with safe radiation doses: Report of two rare cases

INTRODUCTION

Radiation-induced optic neuropathy (RION) is still a devastating complication of brain and skull base radiation that has no effective treatment up until today, thus uttermost caution must be taken in treating patients that brain radiotherapy is needed. We present two cases of RION that happened in seemingly safe radiation doses.

CASE DESCRIPTION

A 48-year-old female with a history of pleomorphic pituitary adenoma developed bilateral and painless loss of vision 10 months after radiation to the brain; the total radiation dose was 45 Gy in 25 fractions and no other risk factors of RION were found. Magnetic resonance imaging of the brain depicted bilateral prechiasmatic optic nerve enhancement with involvement of the optic chiasm. Treatment with high doses of corticosteroids was unsuccessful. A 62-year-old female with a history of lung adenocarcinoma and brain metastases presented with a 1-month history of decreased vision in both eyes. He had undergone whole-brain radiotherapy with a total dose of 30 Gy over 10 fractions and concurrent chemotherapy with cisplatin and pemetrexed. Brain magnetic resonance imaging (MRI) with contrast showed bilateral intracranial optic nerve enhancement.

CONCLUSIONS

This is the second case report of RION in a patient with a history of brain radiotherapy and concurrent chemotherapy with pemetrexed. History of chiasmal compression, concurrent use of chemotherapeutic agents, and high fraction size (despite the safety of total radiation dose) were possible contributing risk factors to develop RION in our cases. Hence, adjusting the radiation dose according to the presence of these risk factors is recommended.