What is the best way of removing the lens in cataract surgery, especially in lower income settings?
This review considers two ways of removing the lens. In manual small incision surgery (MSICS) the lens is broken up and removed through a small incision. In extracapsular cataract extraction (ECCE) the lens is removed through a larger incision. ECCE is the standard way of doing cataract surgery in lower income countries.
As people get older, the lens in the eye can become cloudy - this is known as a cataract. Cataract is the most common cause of blindness in the world. Vision can be restored by surgery to remove the cloudy lens. The lens is replaced with a plastic lens. This is known as an intraocular lens or IOL.
We found three randomised controlled trials. The searches are up to date to September 23rd 2014.
A total of 953 people with age-related cataract in India and Nepal were randomly allocated to MSICS and ECCE in these trials.
The data were limited. People whose lens was removed with MSICS were more likely to achieve good functional vision, however, overall not more than 50% of people achieved good functional vision in the two studies. 1.2% of people enrolled in two trials had a poor outcome after surgery with best-corrected vision less than 6/60. There was no evidence of any difference between the two groups with respect to this outcome. Surgically induced astigmatism was more common with the ECCE procedure than MSICS in the two trials that reported this outcome. In one study there were more intra- and postoperative complications in the MSICS group. One study reported that the costs of the two procedures were similar.
Quality of the evidence
We judged the quality of the evidence to be low or very low. There were only three studies and we could not combine the data because of differences in reporting and inconsistency between trials which meant that some of the results were imprecise.
There are no other studies from other countries other than India and Nepal and there are insufficient data on cost-effectiveness of each procedure. Better evidence is needed before any change may be implemented. Future studies need to have longer-term follow-up and be conducted to minimize biases revealed in this review with a larger sample size to allow examination of adverse events.
Age-related cataract is the opacification of the lens, which occurs as a result of denaturation of lens proteins. Age-related cataract remains the leading cause of blindness globally, except in the most developed countries. A key question is what is the best way of removing the lens, especially in lower income settings.
To compare two different techniques of lens removal in cataract surgery: manual small incision surgery (MSICS) and extracapsular cataract extraction (ECCE).
We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 8), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to September 2014), EMBASE (January 1980 to September 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to September 2014), Web of Science Conference Proceedings Citation Index- Science (CPCI-S), (January 1990 to September 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 23 September 2014.
We included randomised controlled trials (RCTs) only. Participants in the trials were people with age-related cataract. We included trials where MSICS with a posterior chamber intraocular lens (IOL) implant was compared to ECCE with a posterior chamber IOL implant.
Data were collected independently by two authors. We aimed to collect data on presenting visual acuity 6/12 or better and best-corrected visual acuity of less than 6/60 at three months and one year after surgery. Other outcomes included intraoperative complications, long-term complications (one year or more after surgery), quality of life, and cost-effectiveness. There were not enough data available from the included trials to perform a meta-analysis.
Three trials randomly allocating people with age-related cataract to MSICS or ECCE were included in this review (n = 953 participants). Two trials were conducted in India and one in Nepal. Trial methods, such as random allocation and allocation concealment, were not clearly described; in only one trial was an effort made to mask outcome assessors. The three studies reported follow-up six to eight weeks after surgery. In two studies, more participants in the MSICS groups achieved unaided visual acuity of 6/12 or 6/18 or better compared to the ECCE group, but overall not more than 50% of people achieved good functional vision in the two studies. 10/806 (1.2%) of people enrolled in two trials had a poor outcome after surgery (best-corrected vision less than 6/60) with no evidence of difference in risk between the two techniques (risk ratio (RR) 1.58, 95% confidence interval (CI) 0.45 to 5.55). Surgically induced astigmatism was more common with the ECCE procedure than MSICS in the two trials that reported this outcome. In one study there were more intra- and postoperative complications in the MSICS group. One study reported that the costs of the two procedures were similar.