Influence of Intraocular Pressure Status on the Formation of Functional Filtering Blebs after Trabeculectomy on Rhesus Monkey eyes

Abstract

Purpose: To improve the maintenance and management of filtering blebs after glaucoma filtering surgeries (GFS), it is essential to understand the effect of intraocular pressure on the formation of function blebs. Here, we utilized a monkey model of chronic ocular hypertension (COHT) to reveal the relationship between pre-operative high-IOP and postoperative bleb fibrosis. Methods: First, four eyes after high IOP induction and four with normal IOPs from eight monkeys received trabeculectomies. Subsequently, IOPs and volume of blebs were measured by Tonopen and anterior segment optical coherence tomography in different time points over 28 days after surgery. Then, histopathology and immunohistochemistry were performed to reveal myofibroblast cells and collagen deposition of filtering blebs. Results: In the early stage after surgeries, IOPs were significantly reduced in the COHT eyes compared to the control eyes. However, IOPs of the COHT eyes gradually increased to 16.75±4.99 mmHg, which was in the normal range but overall higher at the end of the 28-day observation. Consistently, denser fibrosis and scar tissue deposition were observed in the COHT group. Conclusions: Taken together, these results indicated that pre-operative high IOP status might promote bleb fibrosis, compromising the outcome of filtering surgeries. Furthermore, this finding suggested that pre-operative high IOP could induce confounding or effect modification, and more attention should be paid to the following anti-scarring research. From the perspective of translational medicine, controlling IOP before clinical operation is very important to improve the surgical effect.