Background: Trabeculectomy is the standard treatment for patients with primary open angle glaucoma who had failed maximal tolerated medical therapy. The use of Mitomycin C (MMC) or Bevacizumab as adjuvant during trabeculectomy reduces fibrosis which in turn increases the possibility of success in filtrating surgery. However, MMC or Bevacizumab can lead to adverse effects, such as corneal toxicity especially on corneal endothelium, hypotony, formation of avascular cystic blebs, leaks, blebitis, and endophthalmitis.
Objective: To evaluate and compare corneal endothelial cell changes before and after trabeculectomy with subconjunctival Mitomycin C versus trabeculectomy with sub conjunctival Bevacizumab in primary open angle glaucoma patients (1 month and 6 months postoperatively).
Patients and methods: In this study, 20 patients (with 20 eyes) were divided into two equal groups: (Group A) included patients who underwent subscleral trabeculectomy with adjuvant intraoperative use of 0.2mg/ml MMC for 2 min, and (Group B) included patients who underwent subscleral trabeculectomy with subconjunctival injection of 1.25 mg/0.1 ml Bevacizumab.
     Non-contact specular microscope (Topcon sp-1p, Topcon Medical Inc., Japan) was done preoperatively, one month postoperatively and six months post-operatively to assess the corneal endothelium as regard ECD (cells/mm²), CV in cell size, HEX and CCT.
     This prospective comparative study was done at Department of ophthalmology, Sayed Galal University Hospital, Cairo, Egypt, and it was carried out from February 1ˢͭ 2019 to October 30ͭ ͪ  2020.
Results: Six males (60%) and four females (40%) in group A while five males (50%) and five females (50%) in group B. The patients' ages ranged from {25 to 47 years} (mean age35.70±6.70) in group A, and ranged from {20 to 45 years} (mean age 31.20±8.70) in group B. MMC and Bevacizumab did not have the same effect on corneal endothelium.
     There was a significant decrease in endothelial cell density (ECD) after six months post-operatively in both groups with significant difference between the two groups, and insignificant increase in central corneal thickness (CCT) after six months post-operatively in both groups, Also there was a significant changes in coefficient of variation (CV), and percentage of hexagonal cells (HEX), an increase in CV (polymegathism), and decrease in hexagonality (pleomorphism) in both groups, with significant difference between the two groups.
Conclusion: MMC affected all parameters of endothelial cells more than Bevacizumab.