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D. J. Russell, J. J. Dutton, R. L. Baca; Effect of Radiation Therapy on Intraocular Pressure in Patients With Graves' Orbitopathy. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3921.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the effect of radiation therapy (RT) on intraocular pressure (IOP) in patients who have had orbital radiation for Graves’ orbitopathy (GO); and to provide a descriptive analysis of this patient population.
Twenty-four consecutive patients referred for orbital RT for GO from 12/1/2001 through 7/31/2009, were identified. Patients received a total of 2000 cGy fractionated over 10 days. Medical records were reviewed for: demographics, tobacco history, ocular history, history related to Graves’ disease, medications, visual field tests, retinopathy, and physical exam findings (IOP, SPECS scores). IOP measurements for both eyes and SPECS scores were plotted over time and correlations performed. The two tailed Student’s t-test was used to determine statistically significant differences in IOP before RT and 0-3 (T1), 4-6 (T2), 7-12 (T3), and 13-18 (T4) months following RT.
17 of 24 actually received RT. Median age at diagnosis of GO was 54.68 ±8.73 years, median age at time of RT was 56.05 ± 10.12 years. All patients were on steroids prior to RT, 3 had a history of glaucoma, 1 had steroid induced ocular hypertension, 1 had optic nerve swelling related to thyroid disease, 5 had orbital decompression and 2 had eye muscle surgery after RT. IOP was significantly correlated (p<0.05) between right and left eyes in 12 patients. There was no correlation between IOP and SPECS scores in 12 subjects. Mean IOP prior to RT was 18.17±3.97 mm Hg in right eyes and 18.22 ± 3.61 mm Hg in left eyes. There were 10, 11, 12, and 11 patients with data at months T1, T2, T3, and T4 following RT, respectively. There was a significant decrease in IOP of 2.67 mm Hg (±3.9, p=0.04) at T3 and 2.00 mm Hg (± 2.65, p=0.03) at T4 in left eyes, and 2.36 mm Hg (± 3.11, p=0.03) at T4 in right eyes. Patients with glaucoma had a drop in IOP of 5.00 to 6.50 mm Hg at both T2 and T3 (p>0.5).
The effect of RT on GO is important so that appropriate planning for medical and surgical treatment of the IOP can be carried out. This study showed a significant drop in IOP between 7 and 18 months after RT. Patients with glaucoma tended to have larger effects with RT. Disease severity (SPECS scores) tended not to correlate with IOP. Small sample size, lack of controls, and retrospective nature of this study limit the generalizability of the results.
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