Interventional procedure overview of ab interno canaloplasty for open-angle glaucoma

The studies were similar regarding patient characteristics. However, there were differences in the types of glaucoma permitted – some studies permitted pigmentary or pseudoexfoliative glaucoma as well as primary open-angle glaucoma.

The surgical technique was highly consistent across studies. Minor differences were seen in the degrees of cannulation (180 degrees twice, or 360 degrees) and in the postoperative care.

All of the studies included at least some people who had canaloplasty combined with phacoemulsification. Phacoemulsification can often lower IOP by a small amount. Each of the studies that included people who had canaloplasty alone and people who had canaloplasty plus phacoemulsification reported that there were no statistically significant differences in the amount of IOP reduction between the 2 groups.

CE marked devices were used in all studies.

Cases were identified retrospectively from patient records. This can lead to selection bias. Furthermore, outcome data was collected as part of normal follow up – this may have been a reason for the high attrition reported by several studies.

Most studies did not report adjustment for multiple comparisons. Testing many hypotheses without adjustment for multiple comparisons increases the likelihood of finding a statistically significant difference between data that are only different due to chance.

All studies had a before-and-after design. There were no randomised studies identified.

Studies were conducted in the US, Germany, Italy, and Switzerland. There may exist differences in clinical practice between the UK and these countries that prevent generalisation of the findings to a UK context.

The longest follow-up assessment was 2 years, and some studies showed an attenuation of treatment effect over time.