Abstract
Purpose: :
Recently, increased central confocal blue reflectance was reported to be a characteristic finding in patients with Macular Telangiectasia type 2. This was thought to be due to an altered distribution of macular pigment, namely depleted in the centre of the macula with a remaining peripheral ring at 6 degrees eccentricity. The aim of this study was to objectify and quantify the source of the observed increase in confocal blue reflectance.
Methods: :
We used the objective technique of fundus reflectometry, that enables to quantify macular pigment optical density (MPOD), without the need of a reference point. MPOD reflectometry values were obtained at 0, 1, 2, 4, 6 and 8 degrees eccentricity with the Macular Pigment Reflectometer, that also allowed separate in vivo determination of lutein and zeaxanthin. MPOD spatial profiles were obtained using two wavelengths fundus autofluorescence (FAF; at 488nm and 514nm).
Results: :
Comparing the spectral reflectance at 4 and 6 degrees eccentricity revealed a strong resemblance with the absorption profile of the macular pigment, showing that the ring at around 6 degrees eccentricity in autofluorescence and reflectance SLO maps is indeed caused by macular pigment. We found a significant (p<0.001) reduced MPOD within the central 4 degrees eccentricity, whereas at 6 degrees eccentricity MPOD was not different from normative values. Two wavelengths FAF was in accordance with these findings. Further, the data showed a significantly more pronounced reduction of MPOD at the temporal compared to the nasal parafoveal eccentricity. Finally, patients with MacTel type 2 showed a smaller zeaxanthin/lutein fraction than normals.
Conclusions: :
MPOD appears to be reduced in the central 4 degrees retinal eccentricity in patients with Macular Telangiectasia type 2, with spared MPOD values at 6 degrees eccentricity. MPOD was reduced mainly temporal to the fovea. This disease might serve as a model to further study abnormalities of MP distribution in retinal disorders and to elucidate the mechanisms of macular pigment disposition in the retina.
Keywords: macular pigment • retina