Ab-Interno Canaloplasty Effectiveness Categorized Based On Viscoelastic Volume

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

Cloud based International Glaucoma Surgery Registry (IGSR).

Eyes with a glaucoma diagnosis and at least 6-month follow up data were collated from the prospective multicenter cloud-based database (iTGDR, part of the International Glaucoma Surgery Registry – IGSR). All patients underwent canaloplasty via an ab-interno technique with the iTrack or iTrack Advance (Nova Eye Inc., Fremont, USA). Eyes were categorized by stage (early, moderate, severe, advanced), by OVD volume during pressurized viscodilation (less than 49μl of OVD and more or equal 49μl of OVD). Only eyes where the catheter has completed at least 270 degrees circumnavigation of Schlemm’s Canal were included.

72 eyes have been enrolled up to March 2023. Mean baseline IOP was 15.4 mmHg in the less than 49μl of OVD group (2.9 mmHg IOP reduction) and 17.6 mmHg in the more/equal than 49μl group (4.2 mmHg IOP reduction), although there was no statistically significant difference in the IOP reduction or in the postoperative IOP at 6 months between the 2 groups. No eye in the severe or advanced stage was in the less than 49μl group. In the mild glaucoma group (n=40), the IOP reduction was 2.5 mmHg in the less than 49μl group (n=14) and 4.5 mmHg in the more/equal than 49μl (n=26) group, but the reduction difference was not statistically significant. However, mean baseline IOP was statistically significantly different: p=0.02.

This study suggests that volume of OVD delivered while performing ab-interno canaloplasty is correlated with the reduction in mean IOP (more OVD volume equals more IOP reduction) and with the glaucoma stage (early glaucoma eyes with lower baseline IOP receive less OVD) but further studies with more eyes are needed to verify this finding.