Abstract
Purpose:
Type 2 idiopathic macular telangiectasia (MacTel) are characterized by abnormal perifoveal capillary vessels and retinal architecture changes including intraretinal cavities, abnormal macular pigment and ellipsoid zone disruptions. The exact localization of these alterations and their restriction to the macula remain unclear. Fine alterations like intraretinal microcysts have been seldom reported. This study aims at investigating the presence and distribution of these microcysts.
Methods:
Patients affected with Mactel have been retrospectively included. Eyes with other causes of intraretinal exudation have been excluded: choroidal neovascularization, vitreomacular interface disorders, or advanced diabetic retinopathy. Multimodal imaging was performed, including en face optical coherence tomography (OCT), fundus autofluorescence (FAF), fluorescein angiography (FA) and blue reflectance, the latter indicating macular pigment density changes. Cavities larger than 25µm, located at more than 500µm from the foveal center, were defined as microcysts. When observed, they were mapped by en face OCT. After vasculature-guided image alignement, a custom program allowed the projection of this map on the aligned FAF, FA and blue reflectance images.
Results:
Among 27 MacTel eyes from 14 patients retained for analysis (6 females, 8 males, mean age: 64.1 years), 23 eyes presented at least one microcyst. The mean number of cysts was 3.0 per affected eye. In these eyes, a mean of n=2.1 microcysts were located temporally to the fovea versus n=0.75 nasally (P=0.008, Wilcoxon paired test). A mean number of 2.7 microcysts/eye were localized within depleted macular pigment areas, versus 0.6/eye outside (P=0.002, Wilcoxon paired test). A mean number of 1.1 microcysts/eye were localized within hyperfluorescent areas on midphase FA, whereas 1.9 microcysts/eye were observed outside (P=0.32, Wilcoxon paired test). On OCT, the microcysts were mostly located in the inner nuclear and outer plexiform layers. Finally, a correlation was noted in 76% of eyes between areas of disrupted ellipsoid zone and areas of hyper FAF.
Conclusions:
The presence of intraretinal microcysts in MacTel and their distribution suggest that they represent the manifestation of a diffuse macular disease, rather than a local consequence of vascular exudation. The retinal alterations in MacTel may have a wider extension than previously admitted.