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A Eisner, SN Burke, DF Austin, AT Evans, JR Samples; SWS-Cone-Mediated Sensitivity and Tamoxifen Use . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2953.
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Purpose: This research follows from reports that age-related changes of SWS-cone mediated vision are gender-dependent, and from reports that the retina contains estrogen receptors. This research aims to determine whether tamoxifen, a selective estrogen receptor modulator used as adjuvant treatment for estrogen-receptor-positive breast cancer, can affect SWS-cone-mediated sensitivity. Methods: SWS-cone-mediated sensitivity was measured in 2 ways: 1) across the visual field of each eye using Short-Wavelength-Automated Perimetry (SWAP), and 2) in the fovea of one eye using psychophysical increment-threshold techniques to assess changes in SWS-cone mediated sensitivity as a function of time after onset of a bright (3.6 log td) yellow (580-nm) background. A total of 51 women were tested. All used 20 mg tamoxifen daily subsequent to primary treatment for breast cancer, and all had acuity of at least 20/20 in the eye tested foveally and 20/25 in the fellow eye. Results: The SWAP mean-deviation was ≷ 0 in each eye for 10 of the 11 subjects who used tamoxifen < 10 months. In other words, the sensitivity averaged across the visual field and corrected for age exceeded the normal mean for 10 of 11 subjects. From 1-3 years, tamoxifen users separated into 2 subgroups according to whether their mean-deviations were high or low. The mean-deviations of only 2 of 23 subjects were within + 2 dB of 0, whereas the mean-deviations of 11 and 10 subjects were ≷ 2 dB or < -2 dB, respectively. There was no eye-dependent ambiguity. The sensitivities of the low-mean-deviation subjects decreased more at far eccentricities (15- 21) than at near (< 3), as compared with the corresponding difference for high-mean-deviation subjects (p=.014 for eye 1 and p=.034 for eye 2, Mann Whitney U tests). By 4 years or more, 4 of 6 subjects had mean-deviations within + 2 dB of 0 for at least 1 eye. In the fovea, there was no apparent separation into subgroups. The degree of desensitization shortly (20-30 seconds) after onset of the yellow background was correlated (ρ =.47, p=.002) with duration of tamoxifen use, as determined using a multilinear regression model that included age. Conclusion: Tamoxifen affects SWS-cone-mediated sensitivity progressively over a period of years. At the fovea, visual adaptation is altered. This suggests a retinal locus of activity, perhaps involving estrogen receptors. The separation of tamoxifen users into 2 subgroups may potentially have implications for identifying breast cancer patients who are most likely to benefit from a standard 5-year course of tamoxifen treatment.
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