Minimally-invasive glaucoma surgeries (MIGS) for open angle glaucoma: a systematic review and meta-analysis

Methodological quality of the review: Medium confidence

Authors: Lavia C, Dallorto L, Maule M, Ceccarelli M, Fea AM

Region: Not reported

Sector: Glaucoma

Sub-sector: Surgery

Equity focus: None specified

Review type: Other review

Quantitative synthesis method: Meta-analysis and narrative synthesis

Qualitative synthesis method: Not applicable

Background:

Minimally-invasive glaucoma surgeries (MIGS) have been developed as a surgical alternative for glaucomatous patients. However, many clinical studies have been small, non-randomized, and often lacking appropriate control arms. Moreover, these studies often exhibit great variability in measured outcomes, definition of success/failure and follow-up periods.

Objectives:

To analyse the change in intraocular pressure (IOP) and glaucoma medications using different MIGS devices (Trabectome, iStent, Excimer Laser Trabeculotomy (ELT), iStent Supra, CyPass, XEN, Hydrus, Fugo Blade, Ab-interno canaloplasty, Goniscopy-assisted transluminal trabeculotomy) as a solo procedure or in association with phacoemulsification.

Main findings:

In total the authors included 33 studies: nine randomized controlled trials (RCTs) and 21 case series with a total of 2,928 eyes.  The authors report that in RCT studies greater risk of bias were found in detection and in the attrition bias. Three studies were considered at high risk of attrition and detection bias. Unclear risk of allocation concealment was observed in almost all studies, mainly due to incomplete description. No masking of patients, surgeons and outcome assessors seems to be the main concern among the analyzed studies, representing the most serious bias and potentially confounding the outcomes. For the non-randomized studies (NRS), a serious risk of confounding was observed in all studies except one that applied a propensity score based on relevant baseline variables. All other NRS were at serious risk of confounding bias due to a lack of baseline IOP and medication adjustment between groups. Some studies recruited consecutive patients and were judged at low risk of bias in selection of participants; other authors excluded patients who did not complete the follow-up: these papers were therefore judged at serious risk. In before-after studies, most studies were judged at serious risk of bias.

The authors found limited evidence that compared MIGS surgery with medical therapy or other MIGS. They also stated that in before-after studies, MIGS seemed effective in lowering both IOP and glaucoma drug use. The authors report good safety profile for MIGS: IOP spikes were the most frequent complications and no cases of infection or BCVA loss due to glaucoma were reported.

Overall, the authors concluded that although MIGS seem efficient in the reduction of the IOP and glaucoma medication and show good safety profile, this evidence is mainly derived from non-comparative studies and further, good quality RCTs are warranted.

Methodology: 

Inclusion criteria consisted of RCTs and non-RCTs (comparative studies, NRS, and before-after studies). The authors included studies published in English, German, French, Spanish, Portuguese and Italian. Studies about MIGS as a solo procedure or combined with cataract surgery were considered. The main outcome measure was the effect of MIGS devices compared to medical therapy, cataract surgery, other glaucoma surgeries and other MIGS on the change in both IOP and use of glaucoma medication 12 months after surgery.

The authors searched the following databases: MEDLINE Daily and MEDLINE (Ovid), MEDLINE In-Process and Other Non-Indexed Citations, CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register), EMBASE (Ovid), Latin American and Caribbean Literature on Health Sciences (LILACS), CINAHL (EBSCO), Trip Database and The National Institute for Health and Care Excellence (NICE). In addition, the authors hand-searched bibliographies of all included studies. The authors note that grey literature was not considered in this review due to lack of essential information that usually affects this type of research.

Screening of studies and data extraction of included studies were conducted independently. Quality assessment was carried out using the Cochrane’s risk of bias tool.

The authors performed statistical analysis using STATA and used random-effects model. They presented mean and standard error of the IOP and the number of glaucoma medication at baseline and endpoint were used to compute their mean reduction and mean and standard deviation of IOP percentage of reduction.

Applicability/external validity:

The results of this meta-analysis show a decrease of IOP and a reduction of glaucoma medications after MIGS surgery with a low complication rate. The authors note that this could be potentially very relevant for patients and health care providers, allowing a significant number of POAG patients to reduce their glaucoma medication burden.

Geographic focus:

Not reported

Summary of quality assessment:

Overall, medium confidence was attributed to the review. The authors did not conduct thorough search of the literature to ensure that all relevant studies were identified and included in the review.