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M. Vagefi, D.A. Larson, J.C. Horton; Radiation Treatment of Optic Nerve Sheath Meningioma: Visual Improvement Can Begin Before Radiotherapy Ends . Invest. Ophthalmol. Vis. Sci. 2006;47(13):762.
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© ARVO (1962-2015); The Authors (2016-present)
To describe four patients with optic nerve sheath meningioma, in whom visual improvement began to occur even before completion of a standard course of radiation therapy.
A retrospective case review was conducted of patients receiving stereotactic three–dimensional conformal radiotherapy for optic nerve sheath meningioma from 1990 to the present. All patients received a total dose of 54 Gy, using standard fractionation over the course of six to seven weeks. Four patients were identified who had neuro–ophthalmological assessment, including perimetry, either while treatment was underway or immediately afterwards.
Of the patients, three were male and one was female. The mean age at the time of radiotherapy was 38.5 years (range, 35 to 45 years; SD, 4.43). The mean pre–treatment visual acuity as calculated by decimal ratio equivalent was 0.36 (range, 0.10 to 0.67; SD, 0.23). Humphrey visual field indices revealed an average pre–treatment mean deviation of –22.87 decibels (range, –17.77 to –29.04 dB; SD, 5.55) and average foveal sensitivity of 24.5 decibels (range, 14 to 33 dB; SD, 8.10). Visual assessment of two patients was performed within 3 days of post–treatment. Examination of the other patients occurred approximately at one and two weeks prior to the conclusion of radiotherapy. An average improvement in visual acuity of 0.51 (range, 0.33 to 0.90; SD, 0.27), in mean deviation of 14.59 dB (range, 3.46 to 25.74 dB; SD, 9.23) and in foveal sensitivity of 9.0 dB (range, 0 to 20 dB; SD, 8.25) was observed.
A rapid response to radiation therapy may occur in some patients with optic nerve sheath meningioma. In such patients, it may be possible to customize the radiation dose by assessing visual function late during the course of therapy. Such a strategy could reduce the risk of complications, including radiation retinopathy and optic neuropathy.
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