Evaluation of fibrosis in filtering bleb before and after needling revision using polarization-sensitive optical coherence tomography: two case reports.

Abstract

Purpose : Polarization-sensitive OCT (PS-OCT) allows for detection of fibrous scar in the filtering bleb after glaucoma surgery and can be used to compute an objective diagnostic metric, i.e. the fibrosis score. Needling revision is often used to restore the filtering function of failing blebs. We conducted objective evaluation of fibrous scar using PS-OCT before and after needling revision of a failing bleb.

Methods : This study is a descriptive case observation. Two cases undergoing needling revision after filtration surgery were examined by a custom-build PS-OCT. Conventional OCT and birefringence image were computed from raw PS-OCT data. In figures, high birefringence area is displayed by red pixels and overlaid on the conventional OCT image.

Results : Case 1. A 65-year-old woman with primary open angle glaucoma underwent EX-PRESS shunt surgery. Three months after surgery, intraocular pressure (IOP) was 46 mmHg with full glaucoma medication. PS-OCT images showed thin high-birefringent tissue surrounding the internal fluid pool of the bleb (Figure a). Needling revision was done to restore filtering function of the bleb. At three months of follow-up, IOP was 14 mmHg with full glaucoma medication. The fibrosis score before and after the needling revision was 25.3 and 22.7 %, respectively (Figure a-b).
Case 2. A 49-year-old man with primary open angle glaucoma underwent trabeculectomy. Five weeks after surgery, IOP was 28 mmHg with three glaucoma medications. PS-OCT measurements showed that fluid pool was surrounded by a thick high birefringent tissue (Figure c). Bleb needling revision was done to restore filtering function. Despite of full glaucoma medication, IOP was 21 mmHg and high birefringence area of the bleb wall enlarged at one month of follow-up (Figure d). The fibrosis score before and after needling revision was 47.5 and 58.6 %, respectively (Figure c-d).

Conclusions : We presented two cases with successful or failed needling revision. The successful case (Case 1) had lower fibrosis score than the failed case (Case 2) before the treatment. PS-OCT measurements may be one of the prognosis predictive factors of the bleb undergoing needling revision.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.