A Randomized Clinical Trial of Comparison Of Microtrabeculectomy Versus Conventional Trabeculectomy in Primary Open Angle Glaucoma at KLE’S Dr. Prabhakar Kore Hospital and MRC, Belgaum

Abstract

Background and objectives ABSTRACT Currently trabeculectomy is the most popular filtering procedure for glaucoma. Although it has remained the gold standard for the surgical management for more than 30 years, it has a success rate between 67-94% only in primary glaucomas. Several serious postoperative complications are not infrequently associated with trabeculectomy. A recent technique of creating a fistula into the subconjunctival space with minimal disruption of conjunctiva in the form of small flap trabeculectomy known as microtrabeculectomy has been described. It is a much scaled down modification of “full size” procedure and is claimed to be less disruptive to ocular tissues. The purpose of this study is to compare the IOP control in microtrabeculectomy with conventional trabeculectomy and to compare the safety of microtrabeculectomy with conventional trabeculectomy in post operative complications of primary open angle glaucoma. Method The present one year comparative study was conducted in the Department of ophthalmology, KLE Dr.Prabhakar Kore Hospital and MRC Belgaum on 16 patients divided in two groups, Patients in group I underwent the procedure of microtrabeculectomy and patients in group II underwent conventional trabeculectomy. The procedure of microtrabeculectomy included limbal based conjunctival flap 4mm from limbus at superior quadrant. A square shaped lamellar sclera flap of 2x2 mm ( 1/2 to 1/3rd thickness of sclera ) hinged at limbus, dissected until at least 1mm of bluish grey zone was exposed. Anterior chamber was entered at the anterior end. Kelly’s punch was used to remove 1.0. x 1.0 mm of trabecular IV meshwork. Tip of scleral flap was approximated with single 10-0 monofilament suture, after performing peripheral iridectomy.Conjunctival flap was sutured with 10- 0 monofilament ( continuous sutures) . The procedure of conventional trabeculectomy included, a limbal based conjunctivo-tenon flap at 12 O’clock position at least 8-10mm from the limbus. A partial thickness, limbal based, lamellar, square shape scleral flap of 5x5 mm ( 1/2 to 1/3 thickness of sclera ) . The flap was extended well past the limbus into the clear cornea, until 1mm of bluish grey zone was exposed and a 1 x 4mm block of tissue anterior to scleral spur was excised manually. A broad based, peripheral iridectomy was performed and the scleral flap was reapproximated to the scleral bed with three to five monofilament sutures. Conjunctival flap closure was done meticulously with 10- 0 monofilament continuous sutures. All patients were followed up for a minimum period of 3 months. Results Mean pre operative IOP in SFT ( microtrabeculectomy ) i.e. Group I was 30.75± 6.04 mm of Hg and mean post operative IOP was 13.87 ± 2.80 mm of Hg at the end of 3 rd month ( P value < 0.0001) which is both statistically and clinically significant. All patients had IOP ≤ 21 mm of Hg without medication with low lying and shallow diffuse blebs i.e. 100% completed success and with fewer intra and early post operative complications as compared with conventional trabeculectomy i.e. Group II in which the mean pre operative IOP was 30.0± 7.27 mm of Hg and mean post operative IOP was 14.12 ± 2.80 mm of Hg at the end of 3 completed success. V rd month with 100% Conclusions SFT ( microtrabeculectomy ) is a safe procedure that effectively reduces IOP and produces good filtering blebs with fewer complications which is comparable in terms of IOP reduction in the procedure of conventional trabeculectomy and better in terms of safety with no use of pharmacological wound modulators. More studies are needed to ascertain it as an alternative to the conventional trabeculectomy glaucoma surgery.