Our patient had made an excellent systemic recovery following his primary treatment for anaplastic astrocytoma and was doing very well to survive beyond 8 years. Long-term survivors of such malignancies are susceptible to relatively rare effects of their condition and treatment. Specific ocular effects include atrophy and telangiectasia of the periocular skin, dry eye syndrome, neurotrophic corneal ulceration, neovascular glaucoma, cataract, radiation retinopathy and optic neuropathy.5
The incidence of radiation retinopathy depends on both the total radiation dose and fraction size. In a retrospective study of 43 eyes of 25 patients exposed to fractionated external beam irradiation for treatment of advanced nasal and paranasal cancer, Takeda A et al6
reported that the radiation dose and the area of retina irradiated are the most important factors in the development of severe complications in radiation retinopathy. The incidence increases in doses more than 50 Gy,6
although it has also been reported in doses that were considered safe.7
Amoaku and Archer8
found that the interval between external beam radiation treatment and the detection of radiation retinopathy was between 1.0 and 8.5 years (mean 4.7 years). Our patient received 55.07 Gy of radiation, which was higher than recommended dose and directed over a large area due to the aggressive nature of the tumour. Although he presented with ocular symptoms 8.5 years following the treatment, examination suggested chronic maculopathy of no less than 6 months’ duration.
Radiation retinopathy is characterised by delayed onset of slowly progressive occlusive vasculopathy. Histological findings show a thickening of arteriolar and capillary walls and loss of endothelial cells. Associated retinal lesions include microaneurysms, intraretinal oedema, exudation, cotton wool spots and haemorrhage. Cotton wool spots occur transiently with later evolution of large areas of capillary non-perfusion. Widespread capillary closure and retinal ischaemia may lead to retinal and disc neovascularisation, vitreous haemorrhage and retinal detachment. The posterior pole is more sensitive to radiation than the peripheral retina. CNV is a rare manifestation of radiation retinopathy.2–4
Our patient had most of the above mentioned retinal lesions involving the posterior pole. The authors did not observe any cotton wool spots due to chronicity of the maculopathy.
Current options for the management of radiation retinopathy include pan retinal photocoagulation for proliferative disease and focal laser or photodynamic treatment for radiation maculopathy. Radiation maculopathy has also been treated with corticosteroids, anticoagulation and hyperbaric oxygen treatment.5
Vascular endothelial growth factor (VEGF) is an angiopoietic growth factor, which is known to play an integral role in the formation of CNV.9
Recently, several anti-VEGF agents (bevacizumab, pegaptanib and ranibizumab) have become available, which have shown unprecedented efficacy in treating CNV due to age-related macular degeneration and other inflammatory conditions. In a recent series of 21 patients, Finger PT10
reported an improvement in radiation maculopathy following intravitreal bevacizumab with 86% of his patients showing stable or improved visual acuities. Our patient developed radiation maculopathy with CNV and the treatment options would have been photodynamic treatment with intravitreal triamcinolone or intravitreal anti-VEGF treatment. Unfortunately the authors were unable to assess the potential benefits of anti-VEGF treatment in our patient as he refused any active medical intervention.
- Median survival of anaplastic astrocytoma is 2 years. Patients surviving longer should be actively monitored for the relatively rare late effects of the medical condition and treatment.
- Patients who have been exposed to high doses of radiation over a large treatment area have the potential to develop radiation retinopathy, which can present as a reduction or distortion in vision. These patients should urgently be referred for further ophthalmic investigation.
- Intravitreal anti-VEGF agents, which are highly effective in treating many types of CNV, have the potential to effectively treat radiation retinopathy related CNV and preserve vision in such patients.