Functional Progression Following Minimally Invasive Glaucoma Surgery (Migs): A Meta-Analysis Of Visual Field Changes Post Trabecular Microbypass With Istent Technologies

Although intraocular pressure (IOP) remains the sole modifiable risk factor for glaucoma progression, the primary objective of glaucoma management is to safeguard patients' visual function and quality of life. Minimally invasive glaucoma surgeries (MIGSs) are surgical techniques designed to lower IOP with minimal eye trauma. Amongst these techniques, iStent technologies have gained in popularity over the last decade. However, despite well-documented positive effects on IOP and favourable safety profiles, their effect on functional progression has not been formerly studied. This meta-analysis aims to determine the long-term effects of iStent technologies on visual field (VF) progression in glaucoma.

The present report is a meta-analysis conducted on the main electronic medical literature databases (PubMed, EMBASE, Web of Science, Cochrane Library, Ovid).

A search of electronic medical literature databases was conducted to identify studies reporting on iStent technologies. Exclusion criteria included follow-up durations shorter than 12 months, retention rates below 75%, and missing VF data. Fifteen studies, involving 1115 eyes, met the inclusion criteria. Included articles were quality assessed based on some key aspects laid out in the Cochrane collaboration’s tool, and the body of evidence was assessed using the GRADE’s definition of quality. Following data extraction, the weighted mean VF mean deviation (MD) progression rate, IOP reduction, and follow-up duration were computed.

At the end of a mean follow-up of 37.9 months (range 12–96 months), the weighted mean IOP reduction was of 26.6% (range 15.2%–42.3%) from a weighted mean baseline of 19.0 ± 3.1 mmHg. Over the follow-up duration, the weighted mean VF MD progression rate was −0.024 ± 0.34 dBs/year, from a mean baseline of −5.76 ± 5.68 dBs. Of the analysed studies, 46.7% reported on average a statistical improvement in VF MD, and 13.3% reported a mean progression rate in excess of −0.3 dBs/year. The weighted mean MD progression was −0.01 ± 0.42 dBs/year following combined procedures and −0.07 ± 0.62 dBs/year following stand-alone procedures (p = 0.0197). Progression rates did not differ significantly between studies of different types of iStent technologies.

This meta-analysis of 1115 eyes identified a mean functional progression rate of −0.02 dBs/year following trabecular microbypass implantation of iStent technologies in glaucoma. This rate is comparable to that observed in non-glaucomatous eyes (-0.06 to -0.09 dBs/year) and slower than what has been reported in medically treated glaucoma in most large-scale clinical trials (-0.22 to -1.13 dBs/year).