Evaluation by Slitlamp-Adapted Optical Coherence Tomography of the Filtering Function of the Bleb Remaining After Trabeculectomy

Abstract

Purpose:: To evaluate by slitlamp-adapted optical coherence tomography (SL-OCT) the filtering function of the bleb remaining after trabeculectomy.

Methods:: Thirteen patients who each underwent trabeculectomy with a fornix-based conjunctival incision in one eye were included in the study. The appearance of the bleb as revealed with a slitlamp and its internal structure as revealed by SL-OCT were evaluated 1 day, 1 week, and 1 month after surgery. The relation between intraocular pressure (IOP) measured 1 month after surgery and either the appearance or internal structure of the bleb was examined.

Results:: Trabeculectomy was successful in seven patients, in that IOP was <11 mmHg at 1 month after surgery, and it was unsuccessful in six patients (IOP of ≥11 mmHg). The appearance of the bleb was flat in nine cases and diffuse in four cases 1 month after surgery. There was no significant difference in the appearance of the bleb between the successful and unsuccessful treatment groups. The subconjunctival space was located mostly between the posterior edge of the scleral flap and the limbus in all patients of the unsuccessful treatment group but in only two patients of the successful treatment group 1 month after surgery, with this difference being statistically significant (P < 0.05). A relation between IOP and other aspects of the internal structure of the bleb was not apparent.

Conclusions:: These results indicate that the localization of the subconjunctival space after trabeculectomy reflects the filtering function of the bleb. They therefore suggest that aqueous fluid should be drained more posteriorly in order to obtain an adequate reduction in IOP.

Keywords: anterior segment • topography • wound healing