Phacoemulsification versus combined phacotrabeculectomy in the treatment of primary angle-closure glaucoma with cataract: A meta-analysis

Methodological quality of the review: Medium confidence

Author: Wang F, Wu Z

Region: China and Korea

Sector: Glaucoma

Sub-sector: Cataract; treatment

Equity focus: None specified

Review type: Other review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background:

According to estimates from the World Health Organization (WHO), by 2020 primary angle-closure glaucoma (PACG) will affect 20 million people, and 5.3 million will be blind. A large number of studies have demonstrated that the lens extraction can relieve pupillary block, deepen the anterior chamber and make part of the adhesion of anterior chamber angle separated so that it increases the outflow of aqueous humour and obviously reduce intraocular pressure (IOP). The patient’s vision can be improved at the same time. So phaecoemulsification (Phaeco) or phaecotrabeculectomy (Phaecotrabe) have usually been documented for the patients of PACG associated with cataract, aiming to reduce the IOP and improve visual acuity. However, there is a lack of evidence on what kind of operation is more effective and safer.

Objectives:

To compare the efficacy and safety of Phaeco against combined Phaecotrabe in primary angle-closure glaucoma (PACG) with coexisting cataract.

Main findings:

Authors included five randomized controlled trials (RCTs) including 468 patients (468 eyes) with both PACG and cataract. Authors found that Phaecotrabe had a greater intraocular pressure (IOP) lowering effect [preoperative IOP: weighted mean difference (WMD)=0.58, 95% confidence intervals (95% CI, -0.53 to 1.69), =0.31; postoperative IOP: WMD =1.37, 95% CI (0.45 to 2.28), =0.003], a lower number of anti-glaucoma medications [risk ratio (RR)=0.05, 95% CI (0.02 to 0.18), <0.00001] needed postoperatively and less serious damage to the optic nerve [RR=0.48, 95% CI (0.21 to 1.07), =0.07], but a higher risk of complications [odds ratio (OR)=0.04, 95% CI (0.01 to 0.16), <0.00001] compared with Phaeco. The remaining studies indicated that there was no significant difference between the two surgical methods for postoperative best-corrected visual acuity (BCVA) [WMD=-0.05, 95% CI (-0.14 to 0.05), = 0.32] and loss of visual field [RR=1.06, 95% CI (0.61 to 1.83), =0.83].

Methodology: 

Inclusion and exclusion criteria included:

1) types of studies: all randomized controlled clinical trials comparing the effectiveness of Phaecotrabe and Phaeco;

2) types of participants: participants in the trials were people with a diagnosis of angle-closure glaucoma. The trials with patients who had conducted ophthalmic operation and combined other ocular and systemic disease were not included;

3) types of interventions: anti-metabolites could be used intraoperatively in Phaecotrabe group, follow-up time must be more than one year;

4) types of outcome measures: reported outcomes had to include either the primary outcome or one of the secondary outcomes.

The authors conducted a search on PubMed, EMBASE, Scientific Citation Index and Cochrane Library published up to January 2014, the manually searching of relevant conference proceedings was used as the supplement.

Two authors independently screened studies for inclusion according to the customized criteria and then obtained the full text of any paper. Then they extracted data including both the demographic characteristics of studies and baseline characteristics of glaucoma patient from the qualifying studies. One author extracted the data which were double-checked by a second author and discrepancies resolved through discussion among the investigators.

Bias risk of the trials was assessed with the criteria list recommended by the Cochrane Back Review Group. The following criteria were scored yes and no, or unsure by two independent reviewers. If studies met at least five of the 12 items, it was considered low risk of bias.

In addition to the meta-analysis comparing the postoperative IOP reduction between Phaeco and Phaecotrabe, five analyses were conducted. These included: comparison between post-operative best corrected visual acuity (BCVA), reduction in glaucoma medications, incidence of post-operative complications, progression in optic nerve morphology and visual field.

Applicability/external validity:

The authors note that Phaeco alone compared with Phaecotrabe had a better effect in IOP reduction, whereas security declined. They also note that due to the number of included studies, they cannot discuss the applicability of findings.

Geographic focus

Included studies were conducted in China and South Korea; however, the authors do not discuss the applicability of findings to other income settings.    

Summary of quality assessment:

There is medium confidence in the conclusions about the effects of this study as some important limitations were identified. The authors did not conduct a thorough search of the literature to ensure that all relevant studies were identified: it is not clear if authors considered studies written in other languages, searches were restricted to published literature and experts were not contacted for further studies. It is also not clear if the authors extracted data of included studies without compromising the reliability of the review.