gms | German Medical Science

Purpose: Recent findings indicate that besides the vascular changes a neurodegenerative process contributes to the pathogenesis of macular telangiektasia type 2 with paracentral scotomata in presence of preserved central visual acuity. These scotoma can be accurately identified by fundus-controlled microperimetry. In this study progression of these scotoma was analysed using microperimetry and correlated with BCVA and SD-OCT findings.

Methods: In a prospective longitudinal study 78 eyes of 40 patients were examined over a time period of 47±14 months. Distance between microperimetry test points was 1 degree. BCVA was determined using ETDRS charts. SD-OCT images were obtained with the Spectralis HRA-OCT.

Results: 27 of 31 (87%) eyes with preexisting absolute scotoma as opposed to 12 of 47 (25%) of eyes without scotoma at baseline developed at least one additional absolute scotoma. A central visual acuity loss of ≥2 lines occurred in only 23% and 28% of eyes, respectively. On average 1.0±0.88 and 0,27±0.75 new absolute scotoma developed per year. New scotoma were associated with a well-defined loss of the photorecptor layer and a thinning of the neurosensory retina. Alterations in inner retinal layers, i.e. cystoid cavities, showed no topographic association with absolute scotoma.

Conclusions: The results indicate that central visual acuity ist not suitable for assessing the progression of MacTel 2. Microperimetry is more sensitive for detection of progression of functional impairment because of the typical paracentral loss of photoreceptors.Therefore, microperimetry appears suitable as an outcome parameter in future prospective interventional trials.