Abstract
Purpose: :
Two different systems, Adaptive-Optics (AO) Retinal Camera and Spectral Domain Ophtalmoloscopy (SD-OCT) were used to visualize cones in six eyes from 9 patients diagnosed with macular telangiectasia focusing especially on the outer neurosensory macula layers.
Methods: :
Best corrected visual acuity, fundus examination, fundus autofluorescence and pre-injection frames, fluorescein, ICG angiographies and SD-OCT (HRA2 Heidelberg, Germany) were performed and compared to AO images.We used a compact AO camera that corrects ocular aberrations in closed-loop operation at 10Hz, based on a 52-actuator electromagnetic deformable mirror and a 1024 lenslet Shack-Hartmann sensor (Imagine Eyes, Orsay, France). The retina is illuminated by a pulsed infrared LED. Each acquisition provides 20 consecutive images. Ten of them are averaged and digitized to produce an enhanced final image. The AO images are then compared with SD-OCT.
Results: :
The highly reflective photoreceptor inner/outer segment junction (IS/OS) can be used as a pattern of photoreceptors integrity in SD-OCT images. In areas where the IS/OS junction is absent on SD-OCT, no cones are visualized in registered AO images. Regions where intact IS/OS are present correlate with areas where cones are unambiguously visualized using the AO camera. Furthermore, distinct transition zones between intact and absent IS/OS are correlated with AO images. Endly, the subfoveal area is coneless on AO images when there is a hyporeflective hole on SD-OCT; if the IS/OS junction is irregular, the normal cone mosaic is disturbed.
Conclusions: :
SD-OCT analysis of eyes with macular telangiectasia (MacTel) demonstrates regions of apparent photoreceptor disruption which are highly correlated with regions where cones are not visualized using AO. This study shows the synergistic nature of these high-resolution retinal imaging systems.
Keywords: retinal degenerations: hereditary • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • degenerations/dystrophies