Canaloplasty Effectiveness Correlated With Viscoelastic Volume Delivered

To investigate the effectiveness and correlation of pressurized ophthalmic viscoelastic device (OVD) volume delivered during ab-interno canaloplasty to reduce IOP in glaucomatous eyes.

Data collated from prospective multicenter cloud-based database (iTrack Global Data Registry, part of the International Glaucoma Surgery Registry – IGSR).

Eyes with a glaucoma diagnosis and 6-months of follow-up data were included. All patients underwent canaloplasty via an ab-interno technique with the iTrack or iTrack Advance (Nova Eye Inc., Fremont, USA). Outcomes were defined as: complete success: final IOP is ≤18mmHg and final meds is 0; qualified success: final IOP is ≤18mmHg and final meds >0; failure: final IOP is >18mmHg. Only eyes where the catheter had completed at least a 270-degree circumnavigation of Schlemm’s canal were included.

186 eyes have been enrolled. Mean OVD volume delivered was 133.6±28.2µl (range 56–196µl, equal to 20-70 microboluses). At 12 months (n=92), the complete success rate was 34.5% for eyes receiving less than 110µl (39 microboluses) of OVD, 67.4% for eyes receiving 111-165µl (40-59 microboluses) of OVD and 47.1% for eyes receiving more than 165µl (60 microboluses) of OVD. Eyes that received less than 137µl of OVD were on less medications (baseline: 1.79±1.1; 12-month: 0.78±1.1) than those which received more than 137µl of OVD (baseline: 2.28±1.1; 12-month: 1.25±1.4) at the time of surgery  and the difference was statistically significant (p=0.004; p=0.013).

Optimal OVD volume delivered during canaloplasty based on this clinical review is 111-165µl (40-59 microboluses). Eyes with more medications tend to receive increased OVD volume delivery at time of surgery.