Abstract
Purpose: :
To analyze findings derived from combined imaging using confocal scanning laser ophthalmoscopy (cSLO) and high resolution spectral domain optical coherence tomography (SD-OCT) in patients with type 2 idiopathic macular telangiectasia (type 2 IMT).
Methods: :
Eighteen eyes of 9 patients with type 2 IMT were examined. cSLO and SD-OCT images were recorded simultaneously (Spectralis HRA+OCT, Heidelberg Engineering, Germany). The cSLO was used in different imaging modes including fluorescein angiography (FLA), infrared and redfree reflectance as well as fundus autofluorescence (FAF). Conventional time domain (TD) OCT was also performed.
Results: :
Assessment of en face views of three dimensional volume scans revealed hyporeflective spaces that were arranged parafoveally in a petaloid pattern. Usually, there were multiple small spaces separated from each other. Overlays of the late phase FLA with hyporeflective spaces identified on en face images revealed that there was no or only minimal leakage into the hyporeflective spaces. In one patient with an increased foveal signal in FLA imaging, SD-OCT scan revealed a layer of increased reflectance between the retinal pigment epithelial layer and the outer neurosensory retina that was not detectable by TD-OCT. This abnormality suggests accumulation of autofluorescent material.Parafoveally, SD-OCT scans showed an increased signal of the inner neurosensory retina. The area of increased reflectance was correlated with the area of leakage on FLA. The border between the layers in that area showed a ragged outline. An area of decreased confocal infrared reflectance was frequently observed. Such areas were correlated with disruption of the junction between the inner and outer segments of the photoreceptors. In a subset of patients, loss of outer neurosensory layers including the photoreceptors was observed in SD-OCT imaging.
Conclusions: :
Combined cSLO and SD-OCT imaging provides unprecedented in vivo details of the pathology in type 2-IMT. It unequivocally reveals the three-dimensional structure of features previously observed by TD-OCT such as hyporeflective retinal spaces and their behaviour in FLA. It proves to be a useful tool for elucidating disease pathogenesis and may be particularly helpful for longitudinal assessment and monitoring of therapeutic interventions in type 2 IMT.
Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea