Effect of filtering bleb dimensions on postoperative intraocular pressure in deep sclerectomy with collagen implant: a comparative study

Abstract

Introduction: The mechanisms of intraocular pressure (IOP) lowering in deep sclerectomy (DS) are multiple. Using collagen implants is one of the proposed mechanisms of DS success. It has been established to work via maintenance of subscleral decompression lake. However, the relation to conjunctival bleb formation is not fully established.

Method: This study is a retrospective review of the records of 40 eyes of 30 patients with chronic open-angle glaucoma. Patients were divided into two groups; 20 eyes with DS using the Ologen implant (group A), and 20 eyes with DS without implant (group B). The records of UBM that was done for all patients 1 and 6 months after surgery were assessed for the extent, height of conjunctival bleb, depth of AC, the presence of intrascleral bleb and presence of collagen implant.

Results: Extent and height of conjunctival bleb by UBM in group A at 1 and 6 months were 3.46 ± 0.77 mm, 1.6 ± 0.38 and 3.71 ± 1.24 mm, 1.6 ± 0.64, respectively. In group B, they were 2.4 ± 1.12 mm, 0.99 ± 0.69 and 2.69 ± 1.77 mm, 0.81 ± 0.67 mm, respectively; the difference was statistically significant. Correlation using Pearson's correlation coefficient test showed significant negative correlation between extension of the bleb at 6 months and 3rd month postoperative IOP (r = - 0.447, P value 0.048) and significant negative correlation of the height at 6 months to 5th month IOP (r = - 0.491, P 0.028).

Conclusion: Using collagen implant in DS significantly increases conjunctival bleb dimensions, which reflects on lower postoperative IOP.

Keywords: Collagen implant; Conjunctival bleb; Deep sclerectomy; UBM.