Article
Relationship between Contrast Sensitivity and Parafoveal Cone Density in Normal Eyes and Eyes with Retinal Degeneration
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Published: | March 7, 2016 |
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Objective: In eyes with retinitis pigmentosa and with good visual acuity, structural changes by OCT and the decrease of contrast sensitivity (CS) are reportedly well correlated (Yioti GG; 2012). In this study we examined the relationship between CS and the parafoveal cone density in normal eyes and eyes with retinal degeneration.
Materials and Methods: Fifteen normal subjects (age; 26.1±4.5 years) and nine patients with retinal degeneration (age, 35.8±17.7 years) who had visual acuity of 20/60 or better were examined. None of the subjects and patients had cataract or media opacities. The CS was measured by the CSV-1000HGT device with full corrected glasses. Cone mosaic was photographed using custom-built adaptive optics scanning laser ophthalmoscope (AO-SLO, Topcon, Tokyo) at 1º×1º angles of view centered at the fovea. CS was converted to the logarithms (log-CS) and calculated the area under the log-CS function (AULCSF). Parafoveal cone density was calculated in the concentric ring area with a radius between 0.38º and 0.43º from the fovea in which cones were well resolved by AO-SLO and the target was projected.
Results: The CS had a significant positive correlation with the parafoveal cone density in both the normal- (P<0.05, R=0.67) and the retinal degeneration- group (P<0.05, R=0.57). The parafoveal cone density and the CS in the retinal degeneration group were significantly lower than those of the normal group (P<0.001).
Discussion: Our study has demonstrated that CS depends on the parafoveal cone density in the normal subjects. Also, patients with a retinal degeneration have a reduced CS due to a reduction of the cone density even though visual acuity is relatively preserved.
Acknowledgment: This work was supported by the Translational Research Network Program (B03) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.