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S. Grover, W. Phillips, J. Sifrit, A. Dominik, A. Shtjefni, K. Chalam; Perifoveal Retinal Function in Patients With Macular Drusen. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2247.
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Age-related macular degeneration (AMD) is the most common cause of visual loss in people over age 65 years. Retinal function is affected when there are advanced clinical signs of AMD including geographic atrophy, choroidal neovascularization and macular scarring. Macular drusen can sometimes be associated with an early form of AMD. Although the central visual acuity may be normal, it is possible that the retinal function of the perifoveal area may be reduced. The purpose of the present study was to evaluate and correlate various tests of retinal function in patients with macular drusen and good visual acuity.
Seventeen patients with intermediate to large drusen (>63 microns) with visual acuity 20/25 or better were investigated and compared with data from 4 patients with punctate (<63 microns) drusen. All patients with geographic atrophy, diabetic retinopathy or any known retinal degenerative diseases were excluded. Only one eye was included in the study. Each subject underwent visual acuity testing, optical coherence tomography, Humphrey(HVF) 10-2 (68-point) perimetry, microperimetry(MP) 10-2 (68-points) and fundus photography. Both the HVF and MP fields were divided into three similar areas: central <2º (4-points), 2° - 5° (20 points) and >5 º (44 points). The thresholds were averaged in each area.
The average threshold in the <2º area by HVF testing was 31.2 dB in the punctate drusen and 29.9 dB in the large drusen groups. The corresponding thresholds with MP was 16.0 and 15.5 dB, consecutively. Average of thresholds in various areas by HVF showed that the central <2º correlated well with the thresholds in the 2-5º area (r = 0.89; p<.0001) as well as the thresholds in the >5º area (r = 0.89; p<.0001). MP showed that the thresholds in the central <2º area correlated well with the 2 - 5º area (r = 0.71; p<.001) but showed poor correlation with the thresholds in the >5º area (r = 0.36; p>.05).
The threshold in the central <2º with both HVF and MP were within normal range. Both tests showed that the central <2º area had a good correlation with the 2 - 5º area. However, although the central area correlated well with the >5º areas on HVF testing, it did not correlate well with >5º area on MP testing. There is a suggestion that subjects with large drusen have good retinal function not only in the central foveal area but also the perifoveal area. There is also a suggestion that microperimetry may be more sensitive than Humphrey visual field, but more number of subjects will need to be tested.
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