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Several popular surgical microscopes were measured for source radiance. A method has been devised for calculating patient retinal exposure from these instruments. Retinal irradiance is seen to be surprisingly high, assuming dilated pupils and clear media. It ranges from 0.10 to 0.97 W/sq cm. This is one to ten times higher than that produced by an indirect ophthalmoscope. There is evidence linking light exposure during surgery to cystoid maculopathy (Irvine-Gass syndrome).
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Calkins et al. (1979) studied this question.
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