Correlation between Filtering Bleb Clinical Morphology, Anterior Segment Optical Coherence Tomography Findings, and Intraocular Pressure

Purpose: To evaluate usefulness of anterior segment optical coherence tomography (AS-OCT) in evaluation of filtering bleb functionality and to correlate its findings with clinical bleb examination Methods: In this cross-sectional, descriptive study 55 eyes with apparently functional bleb were evaluated. Following a comprehensive ophthalmic examination, filtering bleb grading was performed based on Indiana Bleb Appearance Grading Scale (IBAGS). The bleb was then imaged using AS-OCT. Two radial and tangential scans were obtained. Results: The mean age was 57.69±12.47 years and 29 cases (53%) were female. The mean number of glaucoma medication and intraocular pressure (IOP) were 0.45±0.71 and 14.35±4.67 mmHg, respectively. On AS-OCT examination, the mean bleb height, bleb wall thickness, internal cavity height, posterior extension of the internal cavity were 1.5±0.47 mm, 1±0.4 mm, 0.59±0.28 mm, and 3.15±1.26 mm, respectively. The internal reflectivity was high in 15 cases (27%) and low in 40 cases (73%). There was a positive correlation between the bleb height, bleb wall thickness, and internal cavity height on AS-OCT and IOP. Also, a negative correlation between the posterior extension of the internal cavity and IOP was noted. There was also a positive correlation between the higher IOP and a high internal reflectivity. There has also been a positive correlation between the bleb height at IBAGS and bleb reflectivity at AS-OCT. We also found that there was a positive correlation between the bleb vascularity at IBAGS and internal reflectivity at AS-OCT. Conclusion: AS-OCT seems to be a useful device in evaluation of filtering bleb function. It yields valuable information regarding the internal bleb structures, and its findings are correlated with clinical examination of filtering bleb.