Two different types of giant bleb formation following Ahmed Glaucoma valve implantation

Purpose: This study aims to present two different types of giant bleb formation following Ahmed Glaucoma Valve (AGV) implantation: an anterior enlarged giant bleb and a posterior enlarged giant bleb.

Observations: In Case 1, a 70-year-old Japanese male underwent AGV implantation for neovascular glaucoma in his right eye (OD). Preoperatively, the patient's intraocular pressure (IOP) and best corrected visual acuity (BCVA) were 23 mmHg and 0.6, respectively, OD, while using 3 antiglaucoma topical medications. Two months post-surgery, the patient began experiencing double vision. Slit lamp evaluation revealed no abnormalities, IOP and BCVA were 24.0 mmHg and 0.8, respectively, OD. A posteriorly enlarged bleb in the superotemporal quadrant OD was found to be causing displacement on T2-weighted orbital MRI. The patient underwent surgical excision of the anterior bleb wall. By three weeks post-surgery, the double vision resolved; IOP and BCVA were 17 mmHg and 0.7, respectively, and a normal bleb in the slit lamp evaluation was identified OD. In Case 2, a 10-year-old Japanese female underwent AGV implantation for childhood glaucoma associated with congenital cataract OD. Preoperatively, IOP and BCVA were 30 mmHg and 0.5, respectively, OD, while using 3 antiglaucoma topical medications. She underwent pars plana vitrectomy (PPV) in addition to AGV implantation. Seven months post-surgery, slip lamp evaluation revealed an anteriorly enlarged giant bleb that only cause her a cosmetic concern.

Conclusions and importance: There are two types of giant bleb formation following AGV implantation based on the direction of the enlargement: an anterior enlarged giant bleb and a posterior enlarged giant bleb. The introduction of this classification contribute to better understanding and management of this unusual surgical complication.