Microinvasive glaucoma surgeries (MIGS) are surgeries that try to safely facilitate the removal of the eye’s liquid, called the aqueous, to the outside of the eye in efforts to lower the eye’s pressure or Intraocular pressure (IOP).
MIGS is much safer and has less risks than standard bleb-based surgical procedures for glaucoma: these have a much longer recovery and a much higher risk of infection, endophthalmitis, and loss of the eye.
There are 3 key MIGS procedures used by the majority of US surgeons:
1. Goniotomy performed using the Kahook Dual Blade (KDB) (New World Medical, Rancho Cucamonga, CA, USA) and
2. iStent trabecular bypass device (Glaukos, San Clemente, CA, USA).
3. Cypass: which was taken off the market 8/29/2018 due to concern about long term effects on endothelial cell counts which keep the cornea clear long term.
The only published paper having a head to head comparison between Goniotomy and iStent was sponsored by the Goniotomy company started by Dr. Kahook: obviously they say they are better.
It will take larger randomized trials without corporate funds to see which is really the best for most patients. For now, it is likely they are similar in long term outcomes with Goniotomy having the longer track record in general.
At the end of this post is my Tiered Approach for how best to treat glaucoma. This is still true but would add Cypass if it is put back on market.
A multicenter retrospective comparison of goniotomy versus trabecular bypass device implantation in glaucoma patients undergoing cataract extraction
The aim of this study was to compare intraocular pressure (IOP) outcomes in eyes with cataract and glaucoma undergoing phacoemulsification (phaco) in combination with goniotomy using the Kahook Dual Blade (KDB) or implantation of a single iStent trabecular bypass device.
Retrospective analysis of IOP and IOP-lowering medication reduction in eyes undergoing phaco-goniotomy with KDB (n=237) or phaco-iStent (n=198). Preoperative, intraoperative, and postoperative data were collected through 6 months of follow-up. Outcome measures included mean IOP reduction, mean reduction in IOP-lowering medications, and the proportion of eyes achieving ≥20% IOP reduction or ≥1 medication reduction from baseline.
Mean IOP in the phaco-goniotomy with KDB group decreased from 17.9±4.4 mmHg at baseline to 13.6±2.7 mmHg at Month 6 (P<0.001), with mean medication use decreasing from 1.7±0.9 to 0.6±1.0 (P<0.001). In the phaco-iStent group, mean IOP decreased from 16.7±4.4 mmHg to 13.9±2.7 mmHg (P<0.001), with mean IOP-lowering medication use decreasing from 1.9±0.9 to 1.0±1.0 (P<0.001). Mean IOP reduction from baseline was significantly greater in the phaco-goniotomy with KDB group at Month 6 (phaco-goniotomy with KDB −4.2 mmHg [23.7%] vs phaco-iStent −2.7 mmHg [16.4%]; P<0.001). IOP-lowering medication reduction was greater in the phaco-goniotomy with KDB group compared to the phaco-iStent group (1.1 vs 0.9 medications, respectively; P=0.001). The most common adverse event was IOP spikes occurring in 12.6% of phaco-iStent eyes and 6.3% of phaco-goniotomy with KDB eyes (P=0.024).
Goniotomy with the KDB combined with cataract surgery significantly lowers both IOP and the need for IOP-lowering medications compared to cataract extraction with iStent implantation in glaucomatous eyes through 6 months of postoperative follow-up.
Keywords: glaucoma, goniotomy, intraocular pressure
All authors have received research support from New World Medical in the past. No financial support was received for the work involved in this article. Drs Dorairaj, Kahook, Williamson, Seibold, and Singh are consultants for New World Medical. Dr Kahook receives royalties from licensed patents pertaining to the KDB. Dr ElMallah has no relevant financial disclosures. The authors report no other conflicts of interest in this work.
Dr. Cremers’ Tiered Approach to Glaucoma: