Abstract
Purpose: :
To assess the macular pigment optical density (MPOD) and its topographic distribution patterns in type 2 macular telangiectasis (MT). In this rare disease of the parafoveal capillaries, it is unknown if the MPOD is reduced or if its distribution is changed. Therefore, MPOD was measured in patients with type 2 MT and its distribution was topographically correlated with abnormalities detected by other imaging methods.
Methods: :
19 eyes of 10 patients (median age: 63 years; range 48 – 73 years) were included. Patients were examined by means of fundus biomicroscopy, digital fundus photography, best–corrected visual acuity (VA), fluorescein angiography, and optical coherence tomography. MPOD measurements were performed using a modified confocal SLO (HRA, Heidelberg Engineering, Dossenheim, Germany). MP optical density was calculated using the "two–wavelength–method" from autofluorescence (AF) images, which were aquired at two different excitation wavelengths (488nm, 514nm).
Results: :
All eyes exhibited the typical clinical features of type 2 MT with angiographically late hyperfluorescence temporal to the fovea without macular edema. VA was reduced in all eyes (median 20/40; range: 20/200 – 20/25). MOPD distribution showed a consistent pattern in all patients with type 2 MT: in exact correspondence to the late hyperfluorescent areas temporal to the fovea revealed by fluorescein angiography, MPOD was significantly reduced.
Conclusions: :
There is good topographic correspondence between angiographically visible alterations and reduced MPOD in type 2 MT. These MPOD findings support the notion that in this disease there is apparent assymetry in impairment between the nasal and the temporal parafovea. It remains to be determined why the temporal parafovea is primarily affected in this disease and by what mechanisms macular pigment is depleted in inner neurosensory retinal layers in presence of telangiectatic retinal capillaries.
Keywords: macular pigment • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea