Imaging of Trabeculectomy Blebs Using Anterior Segment OCT

Abstract

 

Purpose:

 

To image trabeculectomy blebs using anterior segment optical coherence tomography (OCT).

 

Methods:

 

This was a prospective cross–sectional study of selected patients who underwent trabeculectomy surgery between 1996 – 2005. All blebs were imaged with the AS–OCT prototype (Carl Zeiss Meditec Inc, Dublin, CA, USA). Standardised non–stereo photographs of all blebs were obtained. A case sheet review was undertaken to determine relevant preoperative data, operative technique, and postoperative outcome. Success was defined as IOP < 21mmHg without the use of topical ocular hypotensive medications.

 

Results:

 

70 blebs in eyes of 49 patients were imaged. There were 28 (57.1%) men and 21 (42.9%) women with a mean age of 69.7 ± 9.3 years. There were 56 (80%) successful and 14 (20%) failed trabeculectomies. All had undergone trabeculectomy with mitomycin C (68 eyes, 97.1%) or 5–fluorouracil (2 eyes, 2.9%), with or without phacoemulsification and intraocular lens implantation. Distinct morphological features were identified in successful and failed blebs. A variety of bleb morphologies were encountered: successful blebs included high, moderate and low blebs, whereas failed blebs were all low blebs with ostial occlusion, flap fibrosis or episcleral fibrosis. AS–OCT was able to demonstrate bleb characteristics such as total elevation, cavity height, wall thickness, tangential and radial dimensions, scleral flap thickness and patency of the internal ostium. Correlation of bleb morphology with functional outcome is ongoing.

 

Conclusions:

 

The anterior segment OCT is a promising tool to image trabeculectomy blebs. It is able to demonstrate features of bleb morphology not visible at the slit lamp.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior segment • clinical (human) or epidemiologic studies: systems/equipment/techniques