Trabeculectomy, which is an incisional filtration surgery, is still the most frequently used surgical method, especially in the surgical treatment of open-angle glaucoma. It is preferred in cases where IOP does not decrease sufficiently with medical treatment and laser treatment, in cases with advanced glaucomatous damage at the first admission and in cases with inadequate treatment compliance. Although there are studies suggesting the application of trabeculectomy as a primary treatment approach without medical treatment and laser treatment, it is not often used as a primary treatment in cases undergoing long-term surgery due to the necessity of re-starting medication and its complications. Fibroblastic activity, which develops as a result of wound healing, is the most important parameter that negatively affects surgical success. Fibroblastic activity is tried to be reduced with the use of anti-metabolites such as mitomycin C and 5 fluorouracil during and after surgery. Especially in cases where antifibrotic agents are used, the risk of bleble-related complications and endophthalmitis is high. Although complications such as hypotonia anterior chamber stenosis are common after surgery, they can be removed and these complications have become less common with the application of adjustable suture techniques. Generally, the sclerostomy is kept small, and if the scleral flap is large and thick, less hypotonia is encountered. Care should be taken that antifibrotic agents do not pass into the anterior chamber during surgery. Because they have very toxic effects on the corneal endothelium. Especially in recent years, the anti-fibroblastic activity of anti-VEGF agents can be used for this purpose. Late complications of bleb, especially blebitis and endophthalmitis, during or after surgery cause new surgical methods to be sought.