High-resolution photoreceptor imaging in idiopathic macular telangiectasia type 2 using adaptive optics scanning laser ophthalmoscopy.

PURPOSE: To study pathologic changes in the photoreceptors in eyes with idiopathic macular telangiectasia (MacTel) type 2 using adaptive optics scanning laser ophthalmoscopy (AO-SLO).
METHODS: Thirteen eyes with nonproliferative MacTel type 2 and 10 normal eyes underwent a full ophthalmologic examination, spectral-domain optical coherence tomography (SD-OCT), and imaging with an original prototype AO-SLO system. All eyes with MacTel type 2 were examined with fluorescein angiography (FA), fundus autofluorescence (FAF), confocal blue reflectance (CBR), and fundus-monitoring microperimetry (MP).
RESULTS: All eyes with MacTel type 2 had ring-like dark areas and/or small patchy regions on AO-SLO images; significantly lower cone density than that of normal eyes in each hemisphere at 0.5 mm from the foveal center; an area with parafoveal reflectance in CBR that was larger than the hyperfluorescence area in FA, the area of increased FAF, the dark areas on AO-SLO, and the area of decreased retinal sensitivity on MP. Dark areas on AO-SLO roughly corresponded to the leakage area in FA, but dark areas were also seen in areas without FA leakage in 11 eyes, including an eye with the earliest clinical signs of MacTel. Visual acuity and retinal sensitivity correlated with mean cone density 0.5 mm from the center of the fovea.
CONCLUSIONS: In eyes with MacTel type 2, AO-SLO revealed unique dark regions in the cone mosaic and decreased cone density that was associated with decreased vision, even in areas with normal vasculature, which suggests that this feature represents early neuronal changes involved in the pathogenesis of MacTel type 2.