Imaging of Surgical Blebs using Spectral Domain Optical Coherence Tomography

Abstract

 

Purpose

 

To evaluate blebs after glaucoma surgery using spectral domain OCT (SDOCT)

 

Methods

 

Cross-sectional study involving the last 21 eyes submitted to glaucoma surgery at the University Eye Clinic of Pavia (Italy) and with a mean follow-up of 5.5±5.3 months. In 13 cases the chosen procedure was a trabeculectomy, with Mitomycin C (MMC) 0.3% used in 9 of them. In 5 cases a filtering device Ex-PRESS 200 was inserted after treatment with MMC 0.3% and in 3 cases a previously failed filtering glaucoma procedure was revised inserting the biodegradable collagen implant iGen (Life Spring Biotech Co, Taipei, Taiwan) on the top of the scleral flap. The blebs were imaged using the SDOCT iVue (Optovue Inc, Fremont, Ca, U.S.A.). A masked observer assessed the ability of iVue in visualizing structures relating to successful filtration: bleb wall thickening, bleb cavity, hyporeflective spaces in bleb wall, scleral flap.

 

Results

 

Post-op intraocular pressure (IOP) was lower in patients submitted to trabeculectomy with MMC (9.3±3.4 mmHg) with a significant difference only compared to trabeculectomy without MMC (p=0.01). In these patients elements of filtration were pointed out in a greater proportion of cases (91.7%) as compared to trabeculectomy (81.2%), insertion of filtering device (75%) and revision of filtration (75%). If we divide all cases on the basis of IOP independently to surgical procedure, filtration is more evident if IOP ≤ 10 mmHg (85.4%) as compared to cases with IOP > 10 mmHg (77.7%).

 

Conclusions

 

SDOCT can provide useful evidence of filtration in the bleb up to the scleral flap. The morphological features can be correlated to IOP. Trabeculectomy with MMC 0.3% can provide good filtration and control of IOP. However SDOCT cannot give information under the scleral flap due to limited deep tissue penetration.

 

 

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 550 imaging/image analysis: clinical