Abstract
Purpose :
To quantify microvascular changes after pars plana vitrectomy (PPV) and internal limiting membrane (ILM) peeling in patients with idiopathic macular hole (IMH) using optical coherence tomography angiography (OCTA).
Methods :
6x6mm OCTA (Zeiss Angioplex, Zeiss Meditec, Dublin, CA, USA) images of the superficial and deep capillary plexus were analysed prospectively using 2 different algorithms. Ten patients with IMH were included (mean age 67.9y). OCTA images of the study eye and the fellow eye were acquired one day (T1) before surgery, 4 weeks (T2) and 12 weeks (T3) after surgery. Prior to image analysis, global contrast was normalised across images and the threshold for vessel detection was adapted to local brightness. Microvascular alterations were assessed measuring vessel density and analysing the shortest distance to the surrounding vessels of all intercapillary pixels. Only vessels enclosed by an ETDRS Grid centred on the fovea were analysed. The central sector was excluded to avoid segmentation errors due to IMH.
Results :
Images of 8 study and 7 fellow eyes were analysed. The vessel density of study eyes (mean/SD [%] superficial: (T1) 39.5 ± 0.01 (T2) 39.8 ± 0.02 (T3) 39.7 ± 0.02; deep: (T1) 39.2 ± 0.02 (T2) 41.6 ± 0.02 (T3) 40.9 ± 0.03) showed a significant increase in the deep plexus between the first and the last visit after surgery (p=0.038, Friedman test and Wilcoxon post hoc test p=0.016). Intercapillary pixel analysis was not significantly different between visits but showed a trend towards lower distance values in the deep plexus. Comparison between study eyes and fellow eyes at each timepoint showed no significant difference with both approaches.
Conclusions :
ILM-peeling caused a significant increase in vessel density of the deep plexus. These results are in line with previous studies showing alterations after ILM peeling only in the deep plexus with an increase of vessel density. Further increasing of the group size might reveal subtle changes in the intercapillary distance of the deep plexus.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.