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Ching-Lung Chen, Vivienne C Greenstein, Huei-Chung Huang, Mohammad Zubair Yameen Arain, Stanley Chang; Cone Density Distribution for Retinitis Pigmentosa Patients with Hyperautofluorescent Rings Compared to Normal Cone Density Distribution Using Adaptive Optics Scanning Laser Ophthalmoscopy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2625.
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© ARVO (1962-2015); The Authors (2016-present)
To compare cone density distribution in patients with retinitis pigmentosa (RP) with hyperautofluorescent rings to normal cone density distribution (NCDD) using adaptive optics scanning laser ophthalmoscopy (AOSLO).
A Canon AOSLO prototype 2 system was used to evaluate the status of cone photoreceptors in the central macula of 4 eyes of 4 RP patients with best corrected visual acuities 20/20-20/30 and hyperautofluorescent rings. AO images were obtained at three locations, 0.5, 1.0 and 1.5 mm from the fovea on nasal retina. They were also obtained from 100 age-matched normal control eyes. After preprocessing registration and fast Fourier transform using the cone cell counting software developed by Canon Inc., the cone density of up to 4 selected 100X100 um areas within each of the 3 locations was counted manually and the distance from the fovea to the center of each area was measured by Aria software. All the data including cone density and distance from the fovea were compared to the age matched NCDD. In addition to AOSLO imaging 10-2 visual fields were obtained (Carl Zeiss Meditec Inc.). The cone density distributions were compared to visual field sensitivities at similar locations.
When cone density for the 4 RP patients was calculated for 0.5, 1.0 and 1.5 mm and compared to the density for normal control eyes the values appeared to be very similar. However when the “true” distance, the distance from the fovea to the center of the area selected for counting, is used in the calculation and the results are compared to NCDD, cone density was significantly lower in the 4 RP eyes compared to the age-matched NCDD values. This decrease in density was found not only on and outside the border of the hyperautofluorescent ring where cone mediated visual sensitivity was markedly decreased, but also within the hyperautofluorescent ring.
The detection of cone photoreceptor abnormalities in patients with RP is enhanced by quantitative measurements of cone density.
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