Abstract
Purpose: :
Macular Telangiectasia Type 2 (MacTel) preferentially affects the temporal macula and leads to difficulties with driving, reading and can potentially result in blindness. Preliminary observations indicated that MacTel patients had hyper-autofluorescent Drusen-like deposits (HyperAFD). This study aims to establish the presence, distribution and the progression of HyperAFD in patients, their family members (FMs) and unrelated controls (UCs).
Methods: :
Gradable quality colour fundus (CF), Autofluorescence (AF), Optical Coherence Tomography (OCT) and Fluorescein Angiography (FFA) images of MacTel patients, CF, AF and OCT of their family members (FMs) and CF and AF of unrelated controls’ (UCs) images were graded for the presence or absence, location and number of HyperAFD using the standard MacTel grid. Differences in count per subfield were calculated with analysis of variance and significant differences were considered to exist for p-value ≤ 0.05.
Results: :
Of those with good quality complete image sets available, 78% of patients, 48% of FMs and 40% of UCs had HyperAFD at presentation. The highest quality image sets from 31 MacTel patients, 17 FMs and 24 UCs were selected to study spatial distribution of HyperAFD. Patients had the highest number of macular HyperAFD in the areas known to be affected by MacTel, the inner and outer temporal regions while in FMs and UCs there was no predilection. We found that number of HyperAFD in patients in the temporal region increases with progression of the disease (Gass-Blodi classification stages I-V; 1, 10.1, 13.4, 13.7 and 19.4 respectively). The average size of the HyperAFD was 63.6±5.6µm (ranging between 20-220 µm). One-to-one correlation of drusen in AF, CF and late-phase FFA images showed that HyperAFDs do not take up fluorescencein but can be detected on CF and preliminary data using spectral domain OCT suggest that HyperAFD are located within Bruch’s membrane.
Conclusions: :
HyperAFD are found in excess in patients with MacTel when compared to FMs and UCs. HyperAFD has a strong preference to the temporal macular region in MacTel patients and show a clear increase in numbers as the disease progresses; therefore we propose that HperAFD could serve as a surrogate biomarker of disease progression.
Keywords: drusen • imaging/image analysis: clinical • macula/fovea