Abstract
Purpose: :
Type 2 Macular Telangiectasia (MacTel) is a potentially blinding disease with no known treatment at present. Changes over time on retinal imaging are caused by progressive abnormalities in different properties and structures of the retina: Fluorescein Angiography (FA) demonstrates changes in the deep capillary network, macular pigment optical density (MPOD) in the deposition of Lutein/Zeaxanthin in the inner retina, and the development of pigmentary lesions signify retinal pigment epithelial (RPE) changes. The aim of the study was to compare the relevant changes in order to further define current disease markers and investigate possible common causal event.
Methods: :
Early and late FA changes were graded (1= temporal of the fovea, 2= temporal and nasal, 3= temporal, nasal of and at the fovea (G1, 2, 3 respectively)), MPOD was measured using dual-wavelength autofluorescence (1= temporal decrease, 2= temporal and foveal decrease, 3= temporal, foveal and nasal decrease (MPOD G1, 2, 3). These and the presence or absence of RPE plaques were analysed in 48 eyes of 25 patients of the MacTel Natural History Study. Variations between the different modalities were compared.
Results: :
In early and late FA the distribution of changes was similar (G1 early 18 eyes (38%) late 15 eyes (31%); G2 in 25 eyes (52%), 28 eyes (58%), G3 in 5 eyes (10%) both early and late). MPOD distribution showed a pattern similar to FA: MPOD G1 in 12 eyes (25%), G2 in 31 eyes (65%), G3 in 5 eyes (10%). A congruent classification between early and late FA was found in 90%, between early FA and MPOD in 65% and between late FA and MPOD in 71% of the eyes. Pigment was present in 19 eyes (40%) and was visible in all FA and MPOD groups (FA G1 with pigment in 6 eyes (13%), MPOD G1 in 2 eyes (4%), G2 with pigment in 9 eyes (19%), MPOD G2 in 15 eyes (31%), G3 with pigment in 4 eyes (8%); MPOD G3 in 2 eyes (4%).
Conclusions: :
A good correlation seems to exist between changes in FA (early and late) and MPOD distribution. The two modalities represent different properties of the retina, FA the regulation of the deep capillary network and MP represent transport and deposition, the congruent development of these changes supports the concept of a possible common cause. FA and MPOD and the presence of RPE changes demonstrated a weaker correlation. This set of data is the first to demonstrate some commonality between the vascular and non-vascular elements of the disease and will warrant further clarification on a larger sample when MPOD measurements are available widely.
Keywords: macular pigment • macula/fovea • clinical (human) or epidemiologic studies: natural history