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. Besides pathognomonic angiographic, fundus autoflourscence and blue reflectance signs the disease is characterised by various alterations on optical coherence tomography (OCT). Here we investigated the longitudinal progression of such microstructural findings using SD-OCT technology whilch allows for accurate alignement of tomographic scans in serial scans.
Methods: :
Thirtyfour eyes of 17 patients with MacTel type 2 were examined over a period of 15±10 months using simultaneous SD-OCT (870 nm, 40.000 A-scans/sec) and confocal scanning laser ophthalmoscopy (cSLO) for simultaneous tomographic and topographic in vivo imaging (Spectralis HRA+OCT, Heidelberg Engineering, Germany).
Results: :
Mean retinal thickness diminished by 3,6±3 µm per year in the central 1,2,3 mm grid. The highest rate was noted in the temporal retinal segment, where the retinal thickness decreased by 5,9 µm or 2% of retinal thickness per year. SD-OCT allowed for monitoring of the formation of optical empty spaced between the internal limiting membrane and inner retinal layers. Theses formed in the vicinity of a degeneration of the outer retinal layers followed by a subsequent vertical shift of the inner retinal layers into the parafoveolar atrophie. Continuous diminishing of the retinal thickness was associated with collapse of these inner cavities. A pigment plaque in the parafoveolar retina occurred de novo in one patient. Retinal invasion of thick, hyperreflective dots of irregular shape were noted in 19 patients. In late disease ongoing pigmentary migration led to a thickening of the retina. The advancing intraretinal pigment reached the internal limiting membrane and approached the vitreoretinal interface.
Conclusions: :
Serial SD-OCT imaging allows for identification of the dynamic processes of various phenotypic features atdifferent anatomical layers in MacTel type 2 over time. Accurate quantitation of a progressive thinning of the neurosensory retina at different rates in individual macular segments is not only important to define the natural history of the disease but also for evaluating efficay of future interverventions aiming at slowing the progression of this degenerative retinal disorder.
Keywords: macula/fovea • clinical (human) or epidemiologic studies: natural history • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)