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

Overview

- 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%).

Full Title of Study: “Modified Trabeculectomy With an Extended Subscleral Tunnel Versus Conventional Trabeculectomy for Management of Primary Open Angle Glaucoma (POAG)”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Double (Participant, Outcomes Assessor)
  • Study Primary Completion Date: February 28, 2019

Detailed Description

- 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.

Interventions

  • Procedure: SST in group (A)
    • 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
  • Procedure: trabeculectomy with ESST in group (B)
    • 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)

Arms, Groups and Cohorts

  • Experimental: Group (A)
    • 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
  • Experimental: group (B)
    • 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)

Clinical Trial Outcome Measures

Primary Measures

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

Secondary Measures

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

Participating in This Clinical Trial

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.

Gender Eligibility: All

Minimum Age: 40 Years

Maximum Age: 70 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Rehab mahmoud abdelhamid mohamed
  • Collaborator
    • Cairo University
  • Provider of Information About this Clinical Study
    • Sponsor-Investigator: Rehab mahmoud abdelhamid mohamed, assistant lecturer of ophthalmology,ophthalmology department, medical school – Cairo University
  • Overall Official(s)
    • Riham S Allam, MD, FRCS GL, Principal Investigator, Associate Professor of Ophthalmology , Cairo university
    • Karim A Raafat, MD, Principal Investigator, Professor of Ophthalmology , Cairo university
    • Rehab M Mohamed, MD, Principal Investigator, Assistant lecturer of Ophthalmology , Cairo university

References

El Sayyad F, Belmekki M, Helal M, Khalil M, El-Hamzawey H, Hisham M. Simultaneous subconjunctival and subscleral mitomycin-C application in trabeculectomy. Ophthalmology. 2000 Feb;107(2):298-301; discussion 302.

Nuijts RM, Vernimmen RC, Webers CA. Mitomycin C primary trabeculectomy in primary glaucoma of white patients. J Glaucoma. 1997 Oct;6(5):293-7. Review.

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