Abstract
Purpose :
To correlate ellipsoid zone (EZ) defects as viewed on en face spectral-domain optical coherence tomography (SD-OCT) with retinal sensitivity loss on MAIA microperimetry in type 2 idiopathic macular telangiectasia (type 2 MacTel).
Methods :
Macular SD-OCT volumes and mesopic microperimetry sensitivity maps were obtained during screening and baseline visits of the phase 2 trial of ciliary neurotrophic factor (CNTF) for type 2 MacTel (NTMT-02, Neurotech). Novel software with user-friendly graphical user interface (GUI) and image processing algorithms were developed to estimate EZ defect areas after registering the en face SD-OCT volumes and corresponding individual B-Scans from the screening visit with the microperimetry maps obtained at baseline and screening visits.
Results :
98 eyes of 49 patients were investigated. Mean right eye BCVA was 74.6±8.1 letters (Snellen 20/30) and left eye BCVA was 76.5±9.1 letters (20/30). Microperimetry sensitivity measurements had high repeatability between the two visits that were performed within 5 days of each other (ICC for average retinal sensitivity outside EZ defect: 0.723, 95% CI: 0.613-0.805; ICC for average sensitivity within EZ defect: 0.784, 95% CI: 0.693–0.850; ICC for aggregate sensitivity loss within EZ defect: 0.969, 95% CI: 0.954-0.979). Average retinal sensitivity within the EZ defect area was 14.8±7.6 dB at screening and 14.0±7.1 dB at baseline in right eyes and 14.3±8.7 dB at screening and 12.2±8.8 dB at baseline in left eyes. Aggregate retinal sensitivity loss within EZ defect area was significantly correlated with EZ defect area (Pearson correlation coefficient 0.919, p< 0.001 at screening and 0.919, p<0.001 at baseline). Interestingly, we found areas of EZ defects that corresponded to non-scotomatous loci on microperimetry testing.
Conclusions :
The robust semi-automatic, locally deformable registration algorithm was found to be accurate, as assessed by the nearly perfect overlap of the retinal vessels on en-face OCT with those on microperimetry maps. Our novel software allows determination of functional and structural changes with increasing disease severity and demonstrates that EZ loss on SD-OCT is a surrogate marker and early predictor of photoreceptor functional loss in type 2 MacTel.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.