Kahook Dual Blade Ab-interno Trabeculotomy Versus ab Externo Viscotrabeculotomy in Primary Congenital Glaucoma

Introduction:

Ab externo viscotrabeculotomy is known as an effective surgical procedure used for managing primary congenital glaucoma (PCG) in which the Schlemm's canal (SC) is identified and a metal probe is inserted into the canal and rotated into the anterior chamber (AC) to perforate the SC inner wall.

Recently, Kahook dual blade (KDB) have been developed as one of the micro-invasive glaucoma surgical tools which removes a strip of the trabecular meshwork(TM) at the angle with superiority to simple goniotomy in treating the angle pathology in PCG.

The Kahook dual blade® (KDB) assisted ab-interno trabeculotomy is a simple procedure usually performed at the time of cataract surgery. It doesn't require sutures, and it carries no risk of bleb leaks or infections. It has a a quicker postoperative visual recovery than most other glaucoma treatments. The KDB device is specifically designed to produce targeted and fine tuned parallel incisions in the trabecular meshwork tissue for a quick and effective glaucoma treatment. The KDB's unique design enables precise excision of diseased trabecular meshwork (TM) to access multiple collector channels.

The KDB's unique design enables the operator to perform excisional goniotomy both during cataract surgery and as a stand alone procedure. The Kahook Dual Blade is a precise, intuitive surgical instrument utilized to perform excisional goniotomy.

Purpose:

This prospective study aims to compare KDB ab-interno trabeculotomy to ab externo rigid probe viscotrabeculotomy in patients with PCG.

Methods:

Sixty eyes of with PCG underwent ab-interno trabeculotomy using a KDB or ab externo viscotrabeculotomy. The study will be conducted at Mansoura university ophthalmic Center. Follow-up visits were scheduled at these post-operative dates: first day, first week, first month, 3rd month and then every 3 months for 2 years. Complete success was defined as an IOP from 6 to 17 mmHg at the 2-year follow-up visit, without AGM or further surgical interventions, without any sign of glaucoma progression (increasing corneal diameter, axial length or cup/disc ratio) and without visual devastating complications. Qualified success was defined as fulfilling the same criteria but with the use of AGM.

Preoperative data including age, sex, laterality, type of glaucoma, ocular history, number of glaucoma medications, IOP, cup to disc ratio, and central corneal thickness (CCT) were record. Postoperative data included follow-up durations.

Statistical analysis:

All statistical analysis will be accomplished using IBM SPSS version 20. Assessment of the data normality will be done using both Histogram plot and Shapiro-Wilk's test. Wilcoxon test was used to compare the preoperative and postoperative variables in each group. The comparison between the two groups will be done using Mann-Whitney test for numerical variables and Chi-square test for categorical variables. Kaplan-Meier survival curve will be plotted to estimate the mean survival time and probabilities of failure at different follow-up stages in the both groups. For all tests, P value of less than 0.05 will be considered significant.