Modified Trabeculectomy With an ESST Versus Conventional SST for Management of Primary Open Angle Glaucoma

Study Overview
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Brief Summary
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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%).

Detailed Description
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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.

Official Title
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Modified Trabeculectomy With an Extended Subscleral Tunnel Versus Conventional Trabeculectomy for Management of Primary Open Angle Glaucoma (POAG)

Conditions
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Primary Open-angle Glaucoma

Intervention / Treatment
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* Procedure: SST in group (A)
* Procedure: trabeculectomy with ESST in group (B)


Participation Criteria
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Eligibility Criteria
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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.

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Randomized non-controlled comparative prospective interventional study
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Group (A)<br>20 eyes of 20 patients of uncontrolled POAG administrated intervention will be subscleral trabeculectomy (SST) single surgeon, using retrobulbar anaesthesia with 2% lidocaine, will be performed in all surgeries. Following insertion of a lid speculum, a 10/0 silk bridle suture is inserted at superior limbus if required. In group (A) a conjunctival incision is made at the limbus to create a fornix-based conjunctival flap. A half thickness scleral flap (4 × 4 mm) are created and dissected into the clear cornea. A cellulose microsponge soaked in 0.3 mg/ml MMC solution (Mitomycin-C) is applied to the under surface of the scleral flap over a wide posterior area for 2 ml | Procedure: SST in group (A)<br>* group (A) single surgeon, using retrobulbar anaesthesia with 2% lidocaine, will be performed in all surgeries. Following insertion of a lid speculum, a 10/0 silk bridle suture is inserted at superior limbus if required. In group (A) a conjunctival incision is made at the limbus to create a fornix-based conjunctival flap. A half thickness scleral flap (4 × 4 mm) are created and dissected into the clear cornea. A cellulose microsponge soaked in 0.3 mg/ml MMC solution (Mitomycin-C) is applied to the under surface of the scleral flap over a wide posterior area for 2 ml<br>* Other names: conventional trabeculectomy;|
| Experimental: group (B)<br>20 eyes of 20 patients of uncontrolled POAG d Administrated intervention will be ESST another longitudinal scleral groove will be created in the center of the deep scleral bed area measured about 1.5 × 6 mm.In both groups, standard trabeculectomy of equal size (two bites aside) is created by a Kelly punch ( 1 mm) | Procedure: trabeculectomy with ESST in group (B)<br>* group (B), another longitudinal scleral groove will be created in the center of the deep scleral bed area measured about 1.5 × 6 mm.In both groups, standard trabeculectomy of equal size (two bites aside) is created by a Kelly punch ( 1 mm)<br>* Other names: extended subscleral tunnel;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change from baseline intraocular pressure at first day postoperative | mmHg | day one postoperatively | 
| change from baseline intraocular pressure at 4 weeks | mmHg | , 4 weeks. | 
| change from baseline intraocular pressure at 6 weeks Ultrasound bimicroscopy (UBM) | mm Hg | 6 weeks post-operatively. | 
| change from baseline intraocular pressure at 3 months | mmHg | 3 months postoperatively | 
| change from baseline intraocular pressure at 6 months | mmHg | 6 months postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change from baseline best corrected visual acuity (BCVA) at 6 months | logarithm of minimal angle of resolution (log MAR) | at the end of 6 months | 
| extent of filtering bleb area by ultrasound of bio-microscopy (UBM) | width, depth and height of filtering bleb area in millimeter | 6 weeks postoperatively | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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subscleral trabeculectomy, extended subscleral tunnel, mitomycinC