Efficacy and Safety of the ab Interno Trabeculectomy With Kahook Dual Blade Combined With Cataract Surgery Versus Cataract Surgery Alone: a Prospective, Single-center, Randomized Study

This new device, the Kahook Dual Blade, has been specially designed to create a gentle cut compared to other cutting-devices that also remove the trabecular meshwork. Preclinical investigation showed no harm in the surrounding tissues. Only two prospective studies have been published, showing good results in terms of IOP reduction and a significant cut-off in the glaucoma medications. However, to better assess the real effect, a prospective comparison with cataract surgery or any other trabecular technique should be performed. We also aimed to determine the safety of the procedure.

Study design A prospective, randomized controlled, interventional study was conducted to determine the efficacy and safety of the Kahook Dual Blade. Patients with cataract and open-angle glaucoma or ocular hypertension (OHT) were included.

Subjects Patients were consecutively recruited from the Department of Glaucoma. Eligible patients were asked to participate if cataract surgery was indicated due to best-corrected visual acuity (BCVA) bellow 0.5 (in decimal scale), and moderate IOP reduction and a cut-off of the glaucoma medications was also aimed. Patients included in the study had been previously diagnosed with primary open-angle (POAG), pseudoexfoliative glaucoma (PSX) or OHT, and mild-to-moderate glaucoma according to the Hodapp-Parrish-Anderson classification, preoperative IOP ≤ 24 mmHg on at least one hypotensive medication, and coexistence of cataract without narrowing the angle (visible scleral spur at least in 2 quadrants). Both eyes from the same patient could be eligible if they both met the inclusion criteria.

Subjects who did not fulfill the inclusion criteria were excluded: patients with other glaucoma subtypes (elevated episcleral venous pressure, orbital occupancy, Sturge-Weber syndrome or any type of angle-closure glaucoma). Patients who underwent any intraocular surgery in the previous six months, including any laser or surgical intervention for glaucoma, or patients with any ophthalmic diseases that may interfere with tests were excluded. Severe or end-stage glaucoma or those with an indication of filtering or glaucoma drainage implant surgeries due to a high IOP with the maximum tolerated medication or glaucoma progression were also exclude.

All subjects were thoroughly examined before clinical intervention. This included a medical history review, slit-lamp examination, IOP determination with hand-held applanation tonometer, gonioscopy, dilated fundus examination, endothelial cell count (ECC) including cell and size automated detection with specular microscopy (EM-3000, Tomey Corporation, Nagoya, Japan), simulated keratometry (simK) determined by topography (Pentacam®, Oculus, Wetzlar, Germany), and standard automated perimetry (VF) (G1-Tendency Oriented Perimeter, Octopus® 1-2-3, Haag-Streit, USA).