Purposes: To assess the morphology of filtering bleb after Ahmed valve glaucoma surgery using anterior segment optical coherence tomography (AS-OCT) and propose a classification system for bleb according to clinical and AS-OCT parameters.
Methods: A total of 48 patients who had received Ahmed valve implantation participated in this prospective study. Clinical morphology and AS-OCT parameters were measured post-operatively at 1 week, 1 month, 3 months and 6 months. The relationship between the bleb morphology and success of the surgery was evaluated. Success was defined as IOP < 21 mmHg with a maximum of 2 glaucoma medications.
Results: Photographic standards illustrating clinical bleb morphology characteristics was selected from the clinical images in the study. Bleb vascularity and color was significantly correlated with the hypertensive phase and surgery success (p<0.05). Bleb analysis using AS-OCT revealed a significant reduction in bleb wall thickness and increase in bleb wall reflectivity at 1 month, which was mostly associated with hypertensive phase. There was a significant correlation between AS-OCT parameters (bleb wall thickness, bleb wall reflectivity, bleb height, microcyst) and surgery success (p<0.05).
Conclusions: The morphology of filtering bleb based on clinical image and AS-OCT parameters shows significant correlation with the surgery success and hypertensive phase incdence. This leads to potential usage of bleb classification in analysis and prediction of Ahmed valve implantation outcome.