Patients with glaucoma sometimes experience a longer-term decrease in intraocular pressure (IOP) after cataract removal, so it may be unclear if additional reduction is produced by minimally invasive glaucoma surgery (MIGS) performed at the same time. One way to begin to test this factor is to compare a MIGS technique as a standalone vs combined procedure.

A retrospective case series published in Ophthalmology Glaucoma analyzed IOP change and number of medications needed for 44 patients with primary open-angle glaucoma (POAG), at least 18 years of age, at a single clinic in El Paso, Texas: 23 eyes who received ab-interno canaloplasty (ABiC) as a stand-alone procedure, and 21 eyes obtaining MIGS in combination with phacoemulsification. The iTrackTM microcatheter (Nova Eye Medical Limited) was employed, and procedures performed from September 2014 to June 2016, with a 36-month follow-up.

Results included similar reductions in IOP from baseline to 12 months for both groups (P <.0001). In the iTrack stand-alone cohort, baseline mean±SD IOP of 20.9±6.1 mm Hg decreased to 13.7±2.3 mm Hg at 12 months and held steady to 13.2±2.1 mm Hg at 36 months. For the combined iTrack with cataract surgery group, baseline IOP of 20.0±3.9 mm Hg fell to 13.0±1.8 mm HG by 12 months and also was stable, 13.5±2.2 mm Hg at 36 months. 


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Patients in both groups also needed fewer medications (P <.0001). The mean number of medicines went from 3.0±0.5 at baseline to 1.6±1.4 at 36 months in the iTrack stand-alone group, and from 2.5±1.1 at baseline to 1.0±1.2 at 36 months in the iTrack with cataract surgery cohort. Although the results were relatively similar between groups, at 36 months, 42.9% of those receiving combined surgery needed 0 medications, compared with 26.1% who underwent standalone iTrack.

No serious ocular adverse events were noted, and other complications included micro-hyphema in 10 eyes, layered hyphemia for 3 patients, IOP spikes of 10 mm Hg or higher in 3 eyes, and 3 individuals needing additional IOP-lowering strategies. Prior research coincides with the present investigation in lack of serious adverse events, but a limited number of reactions reported have been intraoperative bleeding, hyphema, raised IOP, and small descemetolysis near the limbus — most events were self-resolving.

Participants’ mean age was 74.1±9.0 years. Inclusion was based on diagnosis of mild, moderate, or severe POAG, optic disc changes, and the presence of uncontrolled IOP or medication-intolerance. The sample was 56.8% women, 43.2% men, and 77.3% of eyes were of Hispanic ethnicity, 22.7% non-Hispanic ethnicity. IOP-lowering meds were stopped the day after surgery and added back when needed. Analysis limitations included a possible selection bias, as well as 28 of the original 72 eyes were lost to follow-up. A regression to the mean impact was created by missing data for some late referrals, and other factors caused pre-op IOP fluctuation. The investigation’s strength is examining the confounding impact of phacoemulsification.

ABiC is a 360-degree technique with the goal to dilate Schlemm’s canal with a viscoelastic substance for better proximal and distal aqueous drainage. 

Prior 12-month studies have also shown decreased IOP in iTrack stand-alone and combined procedures. “In this study, ab-interno canaloplasty seemed equally effective as a stand-alone procedure or combined with cataract surgery,” according to the researchers.

Disclosure: The study author declared an affiliation with Nova Eye Medical. Please see the original reference for a full list of authors’ disclosures. 

Reference

Gallardo MJ. 36-month effectiveness of ab-interno canaloplasty standalone versus combined with cataract surgery for the treatment of open-angle glaucoma. Ophthalmol Glaucoma. Published online February 17, 2022. doi:10.1016/j.ogla.2022.02.007