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S. K. Bhatia, D. J. Covert, W. J. Wirostko, E. Burnes; Intraocular Pressure Fluctuation in Radioactive Iodine Plaque Brachytherapy for Choroidal Melanoma. Invest. Ophthalmol. Vis. Sci. 2008;49(13):46. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Radioactive Iodine-125 plaque brachytherapy (RIPB) has become a commonly used treatment for choroidal melanoma. To our knowledge, intraocular pressure (IOP) fluctuation during RIPB has not been formally studied. We sought to quantify the perioperative IOP changes during RIPB. Based on clinical experience, we speculated that the IOP would increase while patients have the radioactive plaque in place. In addition, increased age, presence of glaucoma or diabetes mellitus (DM), radiation dose, tumor size, and tumor location may be associated with further IOP elevation.
This was a retrospective record review of all patients undergoing RIPB at Froedtert Hospital in Milwaukee, WI, between 1996 -2007. Patients were identified by billing record search. Exclusion criteria included age less than 18 years, plaque therapy for non-melanotic tumors, and unavailability of preoperative or perioperative data.
Sixty-four patients were included in the analysis. There were 28 men and 36 women. Mean age was 61.3 yrs (standard deviation (SD): 16.1). One patient carried the diagnosis of glaucoma, zero had ocular hypertension, and 8 had DM. Classifying tumors by location showed 34 tumors in the posterior pole, 19 in the midperiphery, and 11 at the ciliary body. The mean maximum IOP change during plaque therapy (ΔIOP) was 8.67 (SD: 6.20), and was not statistically different for these different tumor locations (p=0.1 by ANOVA). Mean tumor height was 4.67 mm (SD: 2.29). There was no relationship between tumor height and ΔIOP using a linear regression model (p=0.55). Mean total radiation dose was 72.3 grays (SD: 8.35). There was no relationship between radiation dose and ΔIOP using a linear regression model (p=0.42). Mean plaque diameter was 16.1 mm (SD: 2.01). There was a limited correlation between plaque diameter and ΔIOP using a linear regression model (r^2=0.1, p=0.01). Patients with DM had a ΔIOP of 5.50; for those without DM ΔIOP was 9.11, which was statistically different (p=0.02). Mean preoperative IOP was 15.8 mmHg (SD: 2.61); this was statistically different from mean maximum IOP during RIPB (p<0.0001), but not statistically different from the IOP one day after plaque removal (p=0.24) (both by paired samples t-test). Patient's mean postoperative IOP was 15.2 (SD: 3.81) and 14.2 (SD: 3.37) on two post-op visits, respectively.
We observed a trend of increased IOP in eyes treated with RIPB that persisted throughout RIPB. This effect resolved rapidly after the plaque was removed. Given this trend, IOP bears monitoring for management of potentially damaging IOP elevations during RIPB.
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