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Elisabetta Pilotto, Luisa Frizziero, Tommaso Torresin, Evelyn Longhin, Francesca Leonardi, Raffaele Parrozzani, Edoardo Midena; Müller cells and choriocapillaris in the pathogenesis of geographic atrophy secondary to age-related macular degeneration. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1138.
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To evaluate, using an integrated morpho-functional approach, geographic atrophy (GA) secondary to age-related macular degeneration in patients with unilateral GA and CNV in the fellow eye (U-GA group) and in patients with bilateral GA (B-GA group).
Patients with U-GA and B-GA and foveal-sparing were consecutively enrolled in a prospective study. In patients with B-GA, if both eyes were eligible, the eye with better visual acuity was included. All included eyes underwent: fundus photography, fundus autofluorescence (FAF), foveal retinal and choroidal thicknesses (RT, CT) calculated by enhanced depth imaging OCT, contrast sensitivity, best corrected visual acuity (BCVA), low-luminance VA (LLVA) and low-luminance deficit (LLD), mesopic and scotopic microperimetry and multifocal electroretinography (mfERG).
Forty patients (eighteen in the U-GA group [18 eyes] and twenty-two in the B-GA group [22 eyes]) were studied. Both RT and GA area were not different between groups (p=0.445 and p = 0.803, respectively). CT was significantly thinner in the U-GA compared to B-GA group (p = 0.020). Both LLVA and LLD were significantly lower in the B-GA versus U-GA group (p=0.033 and p=0.048, respectively). BCVA, contrast sensitivity and mfERG parameters were not different. Mean retinal sensitivity, in both mesopic and scotopic (microperimetry) luminance settings, was not different in the two groups. However, foveal sensitivity was lower in the B-GA group than in the U-GA group, even if not reaching a statistically significant difference (3.08 ± 4.52 dB vs 6.44 ± 4.59 dB, respectively, p=0.195).
Different pathophysiologic mechanisms may be responsible for GA in unilateral (with CNV in the fellow eye) or bilateral GA cases. In unilateral cases, a thinner choroid seems to play a key role. Whereas, in bilateral cases photoreceptors are functionally more severely and earlier compromised than in U-GA. LLVA is a measure of foveal cone-mediated function under conditions of reduced illumination allowing to detect an earlier impairment of cone function. Impairment of Müller cells, histopathologically described in GA, alters cone light sensitivity, initially in low luminance setting. Therefore, in bilateral GA cases, Müller cells and their supported photoreceptors may be primarily involved in the development of GA.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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