Abstract
Purpose: :
Macular telangiectasia type 2 (MacTel type 2) is a rare bilateral macular disease characterised by incompetent macular capillaries and progressive neurosensory macular atrophy. Vascular endothelial growth factor (VEGF) has recently been implicated in the pathogenesis of the disease also in absence of secondary neovascularizations. We determined morphological and functional outcomes following pharmacological VEGF-inhibition in patients with nonproliferative MacTel type 2.
Methods: :
In a prospective interventional trial (ClinicalTrials.gov Identifier: NCT00504400), ten eyes of ten patients with MacTel type 2 received monthly doses of intravitreal ranibizumab (0.5mg) at four week intervals. Serial examinations included biomicroscopy, best-corrected visual acuity (BCVA), fluorescein angiography, spectral domain optical coherence tomography (SD-OCT) with eyetracking (Spectralis HRA+OCT) and fundus-controlled microperimetry (Nidek MP-1).
Results: :
Mean follow-up time was 9.3 months (range 4-11 months). Nine eyes had received at least eight treatments and one eye had received four injections. At all visits within the first 9 months except after the first and fourth injection, mean BCVA had significantly increased by 3.3 (SD 3.1) - 5.3 (SD 4.5) ETDRS letters (P<0.05) in the study eyes, but showed no significant changes in the fellow eyes. Mean retinal thickness within the central 1mm sector measured by SD-OCT decreased significantly (all P<0.01) from baseline after the first injection (mean: -22µm; SD 15.6) and further after the second (mean -27 µm; SD 21.0) and third (mean -32µm; SD 21.2) injection with no relevant reductions thereafter. Reduction in parafoveal vascular calibers and marked decrease in fluorescein angiographic leakage was observed in all eyes following treatment. Microperimetry revealed decreasing (n=3) or improving (n=1) sensitivity temporal to the foveola or no changes in the remaining. (n=5).
Conclusions: :
Inhibition of vascular endothelial growth factor (VEGF) by repeated intravitreal injections of ranibizumab may improve function and decrease telangiectatic vascular calibers, leakage and retinal thickness in patients with nonproliferative MacTel type 2. However, it might be that only functional impairment resulting from leakage into the neurosensory retina is influenced by this therapy, leaving the atrophic disease process unaffected. VEGF’s capacity as a survival factor for retinal neurons needs further consideration in this context.
Clinical Trial: :
www.clinicaltrials.gov NCT00504400
Keywords: macula/fovea • vascular endothelial growth factor