Abstract
Purpose: :
Macular Telangiectasia Type 2 (MacTel2) is characterized by intraretinal capillary proliferation, loss in macular pigment, inner retinal foveal cysts, focal breakdown of the IS/OS line and loss in Muller cells. We used adaptive optics and SD OCT to better characterize retinal structural changes at the microscopic scale in early cases of Mactel2.
Methods: :
27 eyes of 14 patients (mean age 62, 9 females, 6 males) followed-up in the MacTel project and presenting early stage of the disease underwent comprehensive fundus examination including infrared imaging using a flood-illuminated AO camera (rtx1, Imagine Eyes, France). A horizontal band of 4°x4° AO images was acquired through the macula, at locations ranging from 5° temporal to 5° nasal. High resolution SD OCT scans, SLO auto fluorescence and fluorescein angiography (Spectralis/HRA, Heidelberg, Germany) were also recorded. AO findings were compared to those obtained in a matched of normal subjects.
Results: :
In 21 of the 27 eyes examined, AO images showed an altered capillary network in the temporal region. 16 eyes exhibited highly reflective crystalline deposits of size between 3 and 20 µm in the parafoveal inner retina. AO data also revealed patches of intraretinal pigmentation in 9 eyes, of size ranging from 5 to over 100µm. These patched were located at the periphery of the MacTel area in 5 eyes. In several cases this pigmentation was not detectable using conventional fundus examination.The aspect of the cone mosaic was impaired in all cases in various subareas within the MacTel area, in the form of local image haziness and marked decrease in the local density of visible cones. This loss in cone visibility was correlated with alterations in the IS/OS and OS-tip lines seen in SD OCT scans.
Conclusions: :
Although the origin of MacTel disease is not completely understood, the most frequent anomalies observed in this study were focal retinal capillary dilation, associated with crystalline deposits and marked loss in cone mosaic visibility. These findings can be useful in order to define a sensitive marker of the disease progression based on AO imaging
Keywords: retina • imaging/image analysis: clinical • macula/fovea