• To evaluate prospectively the surgical outcome in terms of intraocular pressure control, potential advantages, disadvantages, success rate, complications and bleb morphology of this modified trabeculectomy with an extended subscleral tunnel (ESST) in comparison to the conventional subscleral trabeculectomy (SST) in management of uncontrolled primary open angle glaucoma.
• This study will recruit 40 eyes of (40) candidate patients with primary open angle glaucoma (POAG) who are indicated for surgery.
• The candidate patients will be recruited into 2 equal comparative groups. In group (A) 20 eyes (20 patients) who will undergo conventional (SST) with intraoperative mitomycin C (MMC) (0.03%) and group (B); 20 eyes of 20 patients will undergo trabeculectomy with an ESST also with intraoperative adjunctive MMC (0.03%).

• Different surgical procedures were developed and the principle behind them was to establish a fistula between the anterior chamber and the subconjunctival space to permit the aqueous humour to exit the eye.
• Subscleral trabeculectomy has remained the most commonly performed glaucoma surgery to which the newer operations are compared.Although this procedure is very effective in reducing intraocular pressure (IOP) immediately, surgical failure has often been observed over time due to fibrosis of the surgical site and resultant non-filtering bleb. -Improvement of the complication profile and the efficacy of glaucoma filtering surgery is still a major concern for glaucoma surgeons.Therefore, several modifications, combinations, and new techniques of subscleral trabeculectomy have been described.
• In the current study, a fornix-based conjunctival flap will be fashioned in an attempt to encourage more posterior drainage. In this modified trabeculectomy technique, an additional small perpendicular strip of sclera is removed extending from the AC to 2 mm beyond the edge of the scleral flap thus creating an extended subscleral trabeculectomy facilitating aqueous passage into the posterior subconjunctival space.

Inclusion Criteria:

• Patients with POAG aged from (40- 70) years who are candidate for glaucoma surgery with BCVA ≥ 3/60 to be able to perform visual field testing.
• Non- compliant patients to the medical treatment willing for follow-up visits for at least 6 months post-operatively .

Exclusion Criteria:

• Congenital, traumatic, neovascular, uveitic glaucomas or cases with angle closure glaucoma (ACG) associated with shallow AC.
• Undergoing simultaneous cataract surgery.
• Previous vitreo-retinal surgery including vitrectomy and buckling surgery.
• Other pre-existing ocular cicatrizing diseases.
• Corneal abnormality that precluded reliable applanation tonometry.

study protocol Statistical analysis plan within 6 months after completing the study

participants are going to be randomly assigned into two groups outcomes assessor will asses

1. visual acuity and BCVA
2. IOP using Goldmann applanation tonometry
3. slit-lamp and fundus examination of cup-disc ratio,
4. Ultrasound Biomicroscopy (UBM) to assese ostium patency and extent of bleb area will be done once after 6 weeks post-operatively.
5. Colored photography of the filtering blebs will be performed for grading. Bleb grading will be classified according moorfields grading scale
6. Perimetry will be performed at the end of follow up.