Combined surgery versus cataract surgery alone for eyes with cataract and glaucoma

Background: Cataract and glaucoma are leading causes of blindness worldwide, and their co-existence is common in elderly people. Glaucoma surgery can accelerate cataract progression, and performing both surgeries may increase the rate of postoperative complications and compromise the success of either surgery. However, cataract surgery may independently lower intraocular pressure (IOP), which may allow for greater IOP control among patients with co-existing cataract and glaucoma. The decision between undergoing combined glaucoma and cataract surgery versus cataract surgery alone is complex. Therefore, it is important to compare the effectiveness of these two interventions to aid clinicians and patients in choosing the better treatment approach. Objectives: To assess the relative effectiveness and safety of combined surgery versus cataract surgery (phacoemulsification) alone for co-existing cataract and glaucoma. The secondary objectives include cost analyses for different surgical techniques for co-existing cataract and glaucoma. Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 10), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2014), EMBASE (January 1980 to October 2014), PubMed (January 1948 to October 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to October 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 3 October 2014. We checked the reference lists of the included trials to identify further relevant trials. We used the Science Citation Index to search for references to publications that cited the studies included in the review. We also contacted investigators and experts in the field to identify additional trials. Selection criteria: We included randomized controlled trials (RCTs) of participants who had open-angle, pseudoexfoliative, or pigmentary glaucoma and age-related cataract. The comparison of interest was combined cataract surgery (phacoemulsification) and any type of glaucoma surgery versus cataract surgery (phacoemulsification) alone. Data collection and analysis: Two review authors independently assessed study eligibility, collected data, and judged risk of bias for included studies. We used standard methodological procedures expected by the Cochrane Collaboration. Main results: We included nine RCTs, with a total of 655 participants (657 eyes), and follow-up periods ranging from 12 to 30 months. Seven trials were conducted in Europe, one in Canada and South Africa, and one in the United States. We graded the overall quality of the evidence as low due to observed inconsistency in study results, imprecision in effect estimates, and risks of bias in the included studies. Glaucoma surgery type varied among the studies: three studies used trabeculectomy, three studies used iStent® implants, one study used trabeculotomy, and two studies used trabecular aspiration. All of these studies found a statistically significant greater decrease in mean IOP postoperatively in the combined surgery group compared with cataract surgery alone; the mean difference (MD) was -1.62 mmHg (95% confidence interval (CI) -2.61 to -0.64; 489 eyes) among six studies with data at one year follow-up. No study reported the proportion of participants with a reduction in the number of medications used after surgery, but two studies found the mean number of medications used postoperatively at one year was about one less in the combined surgery group than the cataract surgery alone group (MD -0.69, 95% CI -1.28 to -0.10; 301 eyes). Five studies showed that participants in the combined surgery group were about 50% less likely compared with the cataract surgery alone group to use one or more IOP-lowering medications one year postoperatively (risk ratio (RR) 0.47, 95% CI 0.28 to 0.80; 453 eyes). None of the studies reported the mean change in visual acuity or visual fields. However, six studies reported no significant differences in visual acuity and two studies reported no significant differences in visual fields between the two intervention groups postoperatively (data not analyzable). The effect of combined surgery versus cataract surgery alone on the need for reoperation to control IOP at one year was uncertain (RR 1.13, 95% CI 0.15 to 8.25; 382 eyes). Also uncertain was whether eyes in the combined surgery group required more interventions for surgical complications than those in the cataract surgery alone group (RR 1.06, 95% CI 0.34 to 3.35; 382 eyes). No study reported any vision-related quality of life data or cost outcome. Complications were reported at 12 months (two studies), 12 to 18 months (one study), and two years (four studies) after surgery. Due to the small number of events reported across studies and treatment groups, the difference between groups was uncertain for all reported adverse events. Authors' conclusions: There is low quality evidence that combined cataract and glaucoma surgery may result in better IOP control at one year compared with cataract surgery alone. The evidence was uncertain in terms of complications from the surgeries. Furthermore, this Cochrane review has highlighted the lack of data regarding important measures of the patient experience, such as visual field tests, quality of life measurements, and economic outcomes after surgery, and long-term outcomes (five years or more). Additional high-quality RCTs measuring clinically meaningful and patient-important outcomes are required to provide evidence to support treatment recommendations.