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Elisabetta Pilotto, Enrica Convento, Clelia Karine Abalsamo, Evelyn Longhin, Francesca Guidolin, Edoardo Midena; Microperimetric features of Geographic Atrophy areas identified at the en-face optical coherence tomography. Invest. Ophthalmol. Vis. Sci. 2016;57(12):35.
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© ARVO (1962-2015); The Authors (2016-present)
To functionally characterize the areas of geographic atrophy (GA) identified using en-face OCT, obtained both at the outer retinal layer (OR) and at the choroidal layer (CH).
Twenty-two consecutive eyes (22 patients) were studied with microperimetry and enhanced depth imaging (EDI) OCT. En-face OCT images were obtained both at the outer retinal layer (OR) level and at the choroidal layer (CH) level. GA areas were measured on the en-face OCT images. According to the mean retinal sensitivity, excluding dense scotoma (Se without dense scotoma), studied eyes were divided into three groups: <5 dB (Gr1); 5-10 dB (Gr2); >10 dB (Gr3). Each microperimetry sensitivity map was superimposed to the en-face OCT images, where GA areas were measured. Relative and dense scotoma were calculated in the delineated GA areas.
Mean GA area at OR layer level was significantly different among the groups (13.13 ± 5.03 mm2 in Gr1, 7.80 ± 3.25 mm2 in Gr2 and 3.94 ± 2.35 mm2 in Gr3; p=0.0011). Mean GA area at CH larger level was significantly different among the groups (11.83 ± 5.55 mm2 in Gr1, 7.00 ± 4.29 mm2 in Gr2 and 3.27 ± 2.29 mm2; p=0.0075). Mean GA area at OR layer level was significantly larger than at CH layer level in Gr3 (p=0.0049), but not in Gr1 and Gr2 (p=0.2064 and p=0.3355, respectively). The mean rate of relative scotoma was significantly superior in GA area at OR layer level than at CH layer level in Gr3 (47.70 ± 31.30% vs 34.00 ± 37.30%: p=0.0161), not in G1 and in Gr2 (p=0.3844 and p=0.6254, respectively).
In the early stage of geographic atrophy, when mean retinal sensitivity is less compromised, the larger measured GA area at the OR level, better underlines the wide functional degenerative involvement of the photoreceptor layer.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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