Methodological quality of the review: High confidence
Author: Day AC, Gore DM, Bunce C, Evans JR
Region: Germany, Hungary, Italy, India, China and Brazil
Type of cataract: Age-related cataract
Equity focus: None specified
Review type: Other review
Quantitative synthesis method: narrative synthesis
Qualitative synthesis method: Not applicable
Cataract is the leading cause of blindness in the world, and cataract surgery is one of the most commonly performed operations in the Global North. Preferred surgical techniques have changed dramatically over the past half century with associated improvements in outcomes and safety. Femtosecond laser platforms that can accurately and reproducibly perform key steps in cataract surgery, including corneal incisions, capsulotomy and lens fragmentation, are now available. The potential advantages of laser-assisted surgery are broad, and include greater safety and better visual outcomes through greater precision and reproducibility.
Objectives: To compare the effectiveness of laser-assisted cataract surgery with standard ultrasound phacoemulsification cataract surgery by gathering evidence on safety from randomized controlled trials (RCTs).
Authors included 16 RCTs conducted in Germany, Hungary, Italy, India, China and Brazil that enrolled a total of 1,638 eyes of 1,245 adult participants. Overall, the studies were at unclear or high risk of bias. In 11 of the studies the authors reported financial links with the manufacturer of the laser platform evaluated in their studies. Five of the studies were within-person (paired-eye) studies with one eye allocated to one procedure and the other eye allocated to the other procedure. These studies were reported ignoring the paired nature of the data.
The number of anterior capsule and posterior capsule tears reported in the included studies for both laser cataract surgery and manual phacoemulsification cataract surgery were low. There were four anterior capsule tears and one posterior capsule tear in 1,076 eyes reported in 10 studies (2 anterior capsule tears in laser arms, 2 anterior capsule tears and 1 posterior capsule tear in standard phacoemulsification arms). Review authors were very uncertain as to the effect of laser-assisted surgery compared to standard phacoemulsification surgery with respect to these two outcomes. For postoperative cystoid macular oedema and elevated postoperative intraocular pressures, again the evidence was inconclusive (odds ratio (OR) 0.58, 95% confidence interval (CI) 0.20 to 1.68; 957 eyes, 9 studies, low certainty evidence; and OR 0.57, 95% CI 0.11 to 2.86; 903 eyes, 8 studies, low certainty evidence).
Authors found little evidence of any important difference in postoperative visual acuity between laser-assisted and standard phacoemulsification arms. There was a small advantage for laser-assisted cataract surgery at six months in corrected distance visual acuity (CDVA). However, authors noted that the mean difference (MD) was -0.03 logMAR (95% CI -0.05 to -0.00; 224 eyes, 3 studies, low certainty evidence) which is equivalent to 1.5 logMAR letters and is therefore, clinically insignificant. It was noted that no studies reported patient-reported outcome measures such as visual function. There were no data reported on costs or resource use but three studies reported the time taken to do the surgery. There was little evidence of any major difference between the two procedures in this respect (MD 0.1 minutes, 95% CI -0.02 to 0.21; 274 eyes, low certainty evidence).
Authors concluded that evidence included in this review could not determine the equivalence or superiority of laser-assisted cataract surgery compared to standard manual phacoemulsification for their chosen outcomes due to the low to very low certainty of the evidence available from these studies.
Authors included RCTs where laser-assisted cataract surgery was compared to standard ultrasound phacoemulsification cataract surgery. Authors graded the certainty of the evidence using GRADE. The primary outcome was intraoperative complications in the operated eye. The secondary outcomes for this review were distance visual acuity in the operated eye after initial cataract surgery; patient reported outcome measures (PROMs) at least one month after surgery; any postoperative or long-term complications reported within one year of initial surgery; costs and resource use; and refractive outcomes.
Authors searched CENTRAL, all Ovid MEDLINE resources, Latin American and Caribbean Health Sciences Literature Database, the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov, the World Health Organization International, Clinical Trials Registry Platform and the US Food and Drugs Administration website. Authors did not use any date or language restrictions in the electronic searches for trials. The electronic databases searches were conducted up to 10 May 2016. Two review authors independently screened the search results, assessed risk of bias and extracted data using the standard methodological procedures expected by Cochrane.
Authors assessed for methodological and statistical heterogeneity by examining forest plots of results of the studies and by examining the I2 statistic (%) to assess inconsistency between studies. Authors pooled data using a random-effects model, unless there were three or fewer trials contributing to the analysis, in which case authors used a fixed-effect model.
Of the 16 RCTs that met the inclusion criteria, authors noted that none reported data for every outcome measure. Therefore, authors were not able to provide insights on the applicability/external validity of the results.
Most of included studies (13) were conducted in Europe and three studies were conducted in Brazil, India and China.
Summary of quality assessment:
Overall there is high confidence in the conclusions about the effects of this review. Authors used rigorous methods to screen studies for inclusion, extract data and quality assess the methodological quality of included studies. They also used appropriate methods to pool data of included studies and appropriately addressed limitations of included studies.
Day AC, Gore DM, Bunce C, Evans JR: Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery. Cochrane Database of Systematic Reviews 2016, Issue 7. Art. No.: CD010735.