Intermediate-Term Outcomes Of Combined Cataract Extraction With Kahook Dual Blade Goniotomy Through Postoperative Year Three

Kahook Dual Blade (KDB) goniotomy has been shown to reliably lower IOP and glaucoma medication use in short-term studies with follow up ranging from 6 to 12 months, but there are few reports on outcomes of this procedure beyond postoperative year (POY) 1. Most of the published literature on cataract extraction with KDB goniotomy (phaco-KDB) is in patients with mild to moderate glaucoma, with less known regarding outcomes in those with severe disease. The purpose of the present study is to analyze longer-term outcomes of combined phaco-KDB beyond POY1 and analyze prognostic factors for surgical success.

This study was conducted at a single tertiary care academic institution in the United States. Procedures were carried out by four glaucoma specialists in our department. Approval was obtained by our hospital’s Institutional Review Board prior to commencement of the study.

Ninety-one eyes undergoing phaco-KDB were retrospectively reviewed. Those who carried a diagnosis of primary open angle glaucoma (POAG), secondary open angle glaucoma, or primary angle closure glaucoma (PACG), and who had at least 6 months of postoperative follow-up were included. The primary outcome was surgical success, defined as a decrease in IOP≥20% from the preoperative baseline or reduced medication use, and IOP≤21 without reoperation. Secondary outcomes included intraocular pressure (IOP) and medication use. Mean postoperative-follow up was 37.7±19.4 months.

Surgical success at POY1 and 3 was 67.8%±4.9 and 56.3%±5.5, respectively. Success did not differ between mild/moderate (50.8%±8.0) and severe eyes (61.1%±7.6) through POY3 (p=0.65). Eight eyes (8.8%) underwent reoperation for IOP control. Mean preoperative IOP was 17.4 mmHg±5.9, which was reduced through POY 3 (15.3 mmHg±4.0, p=0.021). Pigmentary/pseudoexfoliative eyes had greater IOP reduction than other eyes (POY1: 30.3%±18.6 vs 11.2±22.9, p=0.008). At POY1, eyes with baseline IOP≤15 mmHg had a 1.5%±23.6 IOP reduction compared to 22.6%±18.9 for eyes with a baseline IOP of≥16 mmHg. Drop use was reduced by 0.7 drops±1.3 through POY3 (p=0.004). Postoperative complications occurred in 18.7% (n=17), with IOP spike (7.7%) most common.

Phaco-KDB offered safe improvement in IOP and medication burden with durable efficacy through POY 3. Success rates were modest with approximately one-half meeting success criteria at POY 3. Surgical success was equivalent regardless of glaucoma severity. Those with pseudoexfoliative or pigmentary glaucoma had greater IOP reduction, while eyes with a preoperative IOP≤15 mmHg had minimal IOP response after phaco-KDB. Longer-term, prospective studies are needed to further characterize the outcomes and prognostic factors for goniotomy.