Assessing Response of Retinal Microvasculature Density and Morphology to Intra-vitreal Dexamethasone Implant Injections for Ocular Inflammatory Disease with Spectral Domain Optical Coherence Tomography Angiography (SD-OCTA)

Abstract

Purpose : Previous studies suggest parafoveal capillary plexi have lower vascular density and complexity in eyes affected by ocular inflammatory disease. This study aims to evaluate changes in SD-OCTA-based metrics of density and morphology in inflammatory disease in response to dexamethasone implant injections.

Methods : A retrospective, observational, longitudinal, Institutional Review Board-approved study of 7 patients (10 eyes) with ocular inflammatory disease treated with dexamethasone injections. The 3x3-mm SD-OCTA scans centered on the fovea were imaged with the ZEISS AngioPlex^TM SD-OCTA device (Cirrus, Carl Zeiss Meditec, Dublin, CA, USA) pre- and post-injection with intravitreal dexamethasone implant (Ozurdex®, Allergan, Irvine, CA). A semi-automated segmentation algorithm was used to assess microvasculature in the superficial (SRL), deep (DRL) and full-thickness (RET) retinal layers. The OCTA-based metrics included vessel area density (VAD), vessel skeleton density (VSD), vessel diameter index (VDI), vessel perimeter index (VPI), and vessel complexity index (VCI). Statistical analysis was performed using paired-sample T-tests.

Results : Mean VAD (0.41±0.02 vs 0.41±0.03), VSD (0.14±0.01 vs 0.14±0.01), VDI (2.99±0.08 vs 2.97±0.11), VPI (0.34±0.02 vs 0.34±0.02), and VCI (6.90x10⁸±3.90x10⁸ vs 6.97x10⁸±5.68x10⁸) in SRL were not significantly different before and after the injection (p>0.30 for all). Mean VAD (0.36±0.03 vs 0.36±0.03), VSD (0.14±0.01 vs 0.14±0.01), VDI (2.64±0.12 vs 2.65±0.16), VPI (0.32±0.02 vs 0.31±0.03), and VCI (6.86x10⁸±4.76x10⁷ vs 6.89x10⁸±5.76x10⁸) in DRL were not significantly different before and after the injection either (p>0.43 for all). Mean injection number was 2.7 ±0.88. Mean time length between pre- and post-dexamethasone imaging was 359.6±82 days.

Conclusions : While there appeared to be a trend towards a difference in the previously described vascular indices prior to and following injection, the study did not show a statistically significant effect on SD-OCTA-based metrics following intravitreal dexamethasone injections in eyes with ocular inflammatory disease. Larger sample size and power may have a significant impact on future results.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Superficial and deep retinal layer 3x3-mm SD-OCTA pre- and post-Ozurdex.