Abstract

P 191

Disease progression in patients with macular telangiectasia type 2 monitored by fundus-controlled microperimetry

Sönke Baumüller1, Peter Charbel Issa1, Frank G. Holz2, Hendrik P. Scholl1
1Universitäts-Augenklinik Bonn; 2GRADE Reading Center, Universitäts-Augenklinik Bonn

Objective
Macular telangiectasia type 2 (MacTel type 2) is a rare bilateral macular disease characterised by incompetent macular capillaries and progressive neurosensory macular atrophy. The disease not only involves slow deterioration of visual acuity, but parafoveal scotomas also develop being a characteristic functional abnormality in MacTel type 2. We analyzed visual acuity loss and progression of parafoveal sensitivity loss in patients with nonproliferative MacTel type 2.
Methods
In a prospective observational longitudinal study, 15 eyes of 8 patients with MacTel type 2 underwent serial standardized microperimetry (MP1, Nidek) and best-corrected visual acuity (BCVA) testing. None of the eyes exhibited retinal or choroidal neovascularisation at baseline or at any follow-up visit. Retinal light increment sensitivity (LIS) was measured at 45 locations on a 8 deg (horizontal) by 4 deg (vertical) matrix of 1 deg spacing centered on the fovea. At follow up, fundus-related microperimetry allowed to re-evaluate exactly the same testing points and to record changes in retinal sensitivity over time. In order to exclude learning effects confounding the data, several exams were performed before the baseline test until overall stable results were obtained.
Results
Mean follow up time was 13 months. Maximal decrease in LIS was ≥10db in 4 eyes (group 1), ≥6db in another 4 eyes (group 2) and changed between -4db and +4db in the remaining 7 eyes (group 3). Two eyes within group 1 lost 7 ETDRS letters, while all other eyes remained stable (+/- 5 letters). All except one eye in groups 1 and 2, but only one eye in group 3 presented with a scotoma at baseline.
Conclusions
Paracentral loss of retinal sensitivity appears to precede loss in distance visual acuity in MacTel type 2. A subset of eyes without scotoma at baseline remained stable while all eyes with a scotoma at baseline showed further deterioration of parafoveal sensitivity. This suggests that a certain degree of disease related retinal damage is necessary before progressing scotomas develop. Fundus-controlled microperimetry may be helpful in studying the natural history and to monitor treatment effects in MacTel type 2.

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