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K. Kroyer, M. Larsen; Dissociation of Rod and Cone Sensitivity Loss in the Retinal Area With a Retinal Pigment Epithelium Tear: A Case Report . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4581.
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Purpose: To test the impact of an acute complete retinal pigment epithelium loss on photopic and scotopic sensitivity. Methods: Photoreceptor thresholds under photopic and scotopic conditions were tested in the affected eye of a 68–year old woman with an RPE tear secondary to drusenoid RPE detachment in AMD. Data were collected using a static 660 nm, 0.46 degree diameter circular stimulus under photopic conditions and a static 532 nm, 0.46 degree diameter circular stimulus after 25 minutes of dark adaption. The stimuli were applied at two locations within the RPE defect at 5 and 8 degrees eccentricity and at two reference points symmetrical opposite of the vertical axis and located outside the RPE defect. Results: The relative sensitivities within the RPE defect and outside the defect in the unaffected retina were compared. Photopic sensitivity was marginally (–1.5 dB) reduced within the RPE defect, whereas scotopic sensitivity was markedly reduced, up to a depth of –19.5 dB within the RPE defect. Conclusions: Scotopic and photopic function was clearly dissociated by the loss of RPE, which caused a deep depression of rod function in the absence of major alteration in cone function. This finding is in agreement with cones having access to an RPE–independent mechanism of photopigment regeneration, which appears to be located in the Müller cell.
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