JUL 05, 2013
This prospective cross-sectional study used adaptive optics scanning laser ophthalmoscopy (AO-SLO) to identify differences in the distribution of photoreceptor abnormalities in idiopathic macular telangiectasia types 1 and 2. Type 1 eyes had significantly lower cone density on the temporal side and type 2 eyes had lower cone density in all areas. Higher mean retinal sensitivity correlated with greater mean cone density. For both types, visual impairment was associated with cone damage.
The study included 11 eyes of with idiopathic macular telangiectasia type 1, 14 eyes with type 2, and 10 normal eyes. All eyes underwent a complete exam, spectral domain optical coherence tomography, and imaging with a novel original prototype AO-SLO system. All eyes with idiopathic macular telangiectasia also underwent fluorescein angiography (FA), confocal blue reflectance and microperimetry.
Eyes with idiopathic macular telangiectasia type 1 and type 2 had significantly lower cone density compared with normal eyes. In eyes with type 1, the FA leakage area was larger than the dark regions on AO-SLO. Twelve eyes with type 2 idiopathic macular telangiectasia showed patchy dark regions in areas without FA abnormalities.
The authors say the study's findings suggest that the dark regions seen on AO-SLO images in idiopathic macular telangiectasia type 2 represent not neuronal damage secondary to vascular abnormalities but rather earlier neuronal changes involved in the pathogenesis of the condition.
They say the results also suggest that vision impairment in idiopathic macular telangiectasia type 1 is mainly related to photoreceptor alterations following cystoid macular edema caused by vascular leakage.