Ellipsoid Zone Mapping and Volumetric Assessment in Normal and Ocriplasmin-treated Eyes

Abstract

 

Purpose

 

Ellipsoid zone (EZ) integrity is a key component of visual outcomes in retinal disease. Transient EZ loss has been described following ocriplasmin therapy. Objectively measuring the integrity of EZ remains difficult. The purpose of this study was to evaluate a novel analysis tool for EZ mapping with en face visualization and volumetric assessment in both normal eyes and eyes receiving ocriplasmin.

 

Methods

 

An automated EZ mapping tool was developed for segmenting the EZ with additional retinal layers, providing linear, area, and volumetric measurements, as well as en face visualization. An IRB-approved retrospective study was conducted of eyes receiving ocriplasmin therapy to assess algorithm function with manual validation. The fellow eye was used as a control eye in cases without concurrent pathology. Scans were analyzed both pre- and post-ocriplasmin.

 

Results

 

The normal eyes (n=13) were analyzed with EZ mapping. The mean EZ-RPE volume was 1.13 +/- .18 mm³ and the mean EZ-RPE central foveal area was 0.20 +/- .03 mm². The EZ maps revealed excellent EZ integrity. Mean EZ map thickness was > 20 microns in 95% of sampled areas. In the ocriplasmin group (n=15), mean EZ-RPE volume was 1.06 +/- .19 mm³ and the central area was 0.16 +/- .03 mm² prior to ocriplasmin injection. The EZ maps revealed good EZ integrity with a mean EZ map thickness of > 20 microns in 92% of sampled areas. One week following ocriplasmin, both EZ-RPE volume and area were significantly reduced (0.81 +/- .20 mm³ and 0.12 +/- .04 mm², respectively, p < 0.005). The EZ maps showed a dramatic reduction EZ integrity with a mean EZ thickness of > 20 microns in only 62% of sampled areas. At 8 week follow-up, EZ volume and area improved to baseline levels and EZ map integrity also improved with EZ thickness > 20 microns in 88% of sampled areas.

 

Conclusions

 

Automated EZ mapping provides in-depth visualization of alterations in retinal architecture and provides a unique opportunity for assessing longitudinal EZ dynamics. In this study, EZ mapping demonstrates the significant transient changes that may be noted with ocriplasmin therapy. This tool may be useful for evaluating additional retinal diseases and improving our understanding of the status of the EZ in retinal pathologies.  

 

Ellipsoid zone mapping prior to (top) and 1-week following ocriplasmin (bottom) with segmentation (A,B), 3D reconstruction (C,D), En face mapping (E,F).