Effect of technique on intraocular pressure after combined cataract and glaucoma surgery: An evidence-based review

Methodological quality of the review: Medium confidence

Author: Jampel HD, Friedman DS, Lubomski LH, Kempen JH, Quigley H, Congdon N, Levkovitch-Verbin H, Robinson KA, Bass EB.

Region: Details not provided

Sector: Combined cataract and glaucoma surgery.

Sub-sector: Intraocular Pressure after combined surgery.

Type of cataract: Age-related cataract

Equity focus: None specified

Review type: Effectiveness Review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not applicable

Background

Authors noted that there are still a number of questions around the surgical management of coexisting cataract and glaucoma, including the efficacy for patients of combined cataract and glaucoma surgery, the efficacy of staged procedures versus combined procedures, the extent to which antifibrosis agents are beneficial, the benefits of one technique of cataract extraction over another, the timing of the procedures and the anatomic location of the operation (one site versus two site).

Research objectives

To analyse the literature pertaining to the techniques used in combined cataract and glaucoma surgery, including the technique of cataract extraction, the timing of the surgery (staged procedure versus combined procedure), the anatomic location of the operation, and the use of antifibrosis agents.

Main findings

33 studies were included in the review consisting of controlled trials, cohort studies, case-control studies and case series, all addressing the management of patients with co-existing cataract and glaucoma.

Two high-quality randomized controlled trials showed a non-statistically significant trend for lower intraocular pressure (IOP) with mitomycin-C (MMC). Nevertheless, authors concluded that a small (2-4 mmHg) benefit was observed from the use of MMC in combined cataract and glaucoma surgery. Six out of the seven studies assessing the effect of postoperative the chemotherapy drug 5-FU found that 5-FU does not improve IOP lowering effect of combined cataract and glaucoma surgery.

Authors found that two-site surgery provides slightly lower IOP (1-2 mmHg) than one-site surgery. IOP is lowered more (1-2 mmHg) when phacoemulsification rather than nuclear expression is used in combined cataract and glaucoma surgery, although the evidence identified for this result was assessed as weak. Authors also concluded that there was insufficient evidence to assess the efficacy of staged or combined procedures or that assess alternative glaucoma procedures versus trabeculectomy in combined procedures.

Further research is necessary to investigate: whether IOP would be lower if glaucoma surgery is performed first followed by cataract extraction rather than combined surgery; to quantify the number of eyes that will not require cataract surgery; and to determine the effects on quality of life on undergoing the two procedures. Authors also note that further reviews would benefit from the inclusion of non-English language articles.

Methodology

Authors included studies comprising randomized controlled trials, cohort studies and case-control studies looking at adult patients with glaucoma undergoing surgery for either cataract or primary open-angle or closed angle glaucoma. Outcomes included the operation performed, the surgical location of the trabeculectomy incision, the antifibrosis agent used, iris manipulation, postoperative medications and method of cataract extraction.

Authors searched PUBMED and CENTRAL (1964-July 2000) as well as six ophthalmology journals, restricting to studies written in English. The abstracts off all identified studies were independently reviewed by two members of the study, but it is not clear if data extraction was conducted independently. Quality scores were only calculated for controlled trials and cohort studies, based on the method used in the Evidence report on anaesthesia management during cataract surgery. The entire team assigned an evidence grade to the conclusions reached about each study question. The mean overall study quality score was 53%.

Applicability/external validity

The authors do not discuss the applicability or external validity of the results of the review although they acknowledge which results are based on stronger, more robust evidence making those results more relevant.

Geographic focus

The geographical location of the studies was not addressed by the authors.

Quality assessment

This review was based on a partially comprehensive search of the literature. Although covering relevant databases and references lists in included studies, authors/experts were not contacted for additional relevant studies, and searches were restricted to published studies written in English. Authors noted that including articles written in English was a limitation of this review, and that relevant articles in other languages may have been omitted and if these were included than conclusions of this review may have been altered. The abstracts of all identified citations were independently reviewed by two authors, but it was not clear if data extraction was conducted independently.

In terms of findings, it was noted that the impact of different techniques on visual field, visual function and quality of life measures were not explored in the review and that further investigation into patient function would be beneficial. Authors conducted a narrative synthesis of the results, which seems appropriate given the variety of types of studies included in the review. Authors acknowledged all limitations of this review and do not draw any strong policy conclusions, thus, there was a medium confidence in the conclusions about the effects of this review.