Iodine-125 brachytherapy treatment poses glaucoma risk
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Patients treated with iodine-125 brachytherapy for uveal melanoma could have a substantial risk for developing open-angle or neovascular glaucoma.
Of 374 eyes treated with iodine-125 brachytherapy, 31 were later diagnosed with secondary open-angle glaucoma, while 25 were diagnosed with neovascular glaucoma in a retrospective case series.
The study included a single surgeon’s patients who underwent primary iodine-125 brachytherapy between Jan. 1, 2004, and June 30, 2014. Those who had a preexisting glaucoma diagnosis were excluded from review. The median follow-up period was 2.14 years.
Eyes that developed secondary open-angle glaucoma had a peak IOP of 33.1 ± 6.8 mm Hg. Thirty received medical therapy, while one required a glaucoma drainage device. Eyes that developed neovascular glaucoma had a mean maximum IOP of 41.5 mm Hg. In 21 eyes, medical therapy was performed, while the other four required a glaucoma drainage device.
The study also recorded additional risk factors.
“The risks of secondary open-angle glaucoma correlated significantly with increased age, greater baseline IOP, larger melanoma size, melanoma involving the ciliary body and in cases where vitrectomy with silicone oil placement was performed for radiation attenuation,” the study authors wrote.
Neovascular glaucoma development was associated with a higher grade of radiation retinopathy severity.
The authors said that the risk for glaucoma development is substantial and that close monitoring should be conducted for any patient receiving iodine-125 brachytherapy.
“The importance of monitoring for secondary open-angle glaucoma and neovascular glaucoma in patients treated with iodine-125 brachytherapy for uveal melanoma must be emphasized so that appropriate treatment may be delivered in a timely fashion to maximize the visual outcome of patients,” they wrote. “Unlike many other complications of radiation therapy, glaucoma is a treatable disease where vision loss may be prevented with prompt therapy.” – by Rebecca L. Forand
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Carol L. Shields, MD
Glaucoma in association with the detection of uveal melanoma is most often found with iris or ciliary body melanoma, where it is usually secondary to angle invasion by tumor seeding. Glaucoma with choroidal melanoma is less common and related more so to neovascular glaucoma. In a survey of 2,111 eyes with uveal melanoma, glaucoma was found at presentation in 7% of eyes with iris melanoma, 17% with ciliary body melanoma and 2% with choroidal melanoma. The presence of glaucoma leads to specific difficulties in management, as open-eye procedures such as trabeculectomy, tube shunt and minimally invasive glaucoma surgery are typically avoided to prevent egress of tumor cells. However, there are further concerns because glaucoma in an eye with iris melanoma poses even greater risk for metastatic disease.
In this analysis of 374 eyes, the authors explored the development of glaucoma following plaque radiotherapy of uveal melanoma. They found the estimated cumulative incidence of secondary open-angle glaucoma at 5 years was 14.7% and for neovascular glaucoma was 13.2%. Risk factors for open-angle glaucoma were older age, elevated baseline IOP, greater American Joint Committee on Cancer (AJCC) T category for anterior and posterior uveal melanoma, ciliary body location and vitrectomy with silicone oil tamponade. Risk factors for neovascular glaucoma included greater AJCC T category for posterior uveal melanoma, cigarette smoking, pseudophakia and high-grade radiation retinopathy.
Many of these factors relate to more advanced tumors that require greater radiation dose that likely led to greater risk for localized or global ischemia of the eye. Importantly, the authors noted that never smoking and panretinal photocoagulation and anti-VEGF for radiation retinopathy, among others, were associated with reduced rate of neovascular glaucoma. Hence, in our practice of ocular oncology, we recommend PRP and anti-VEGF for all patients with irradiated choroidal melanoma.
References:
Shields CL, et al. Ophthalmology. 1987;doi:10.1016/S0161-6420(87)33537-7.
Camp DA, et al. Curr Opin Ophthalmol. 2019;doi:10.1097/ICU.0000000000000550.
Shields CL, et al. J AAPOS. 2012;doi:10.1016/j.jaapos.2011.10.012.
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