EVIDENCE FOR FLACS
An evaluation of current high-level evidence shows that femtosecond laser-assisted cataract surgery (FLACS) provides some advantages compared with conventional phacoemulsification. However, it remains unclear whether the advantages translate into better patient satisfaction and/or quality of life, said Rudy MMA Nuijts MD, PhD.
Speaking during the main symposium on FLACS at the XXXIII Congress of the ESCRS in Barcelona, Spain, Dr Nuijts presented findings from a review of published clinical randomised controlled trials (RCTs) comparing FLACS and conventional phacoemulsification cataract surgery.
Using Forest plots to display individual study findings for various endpoints and the summary statistics from data pooling, Dr Nuijts reported statistically significant differences favouring FLACS over conventional phacoemulsification in analyses of capsulotomy circularity and intraocular lens(IOL)-capsule overlap; IOL tilt and decentration; phacoemulsification energy and effective phacoemulsification time (EPT); endothelial cell loss and early corneal thickness increase; refractive error; and corrected distance visual acuity (CDVA) at six to 12 months postoperatively.
The two procedures did not differ significantly in uncorrected distance visual acuity (UDVA) up to one year postoperatively, increase in clear corneal thickness over time, or complication rates (anterior capsular tears, posterior capsular tears, macular oedema). None of the studies included in the review reported on patient satisfaction or quality of life.
“A meta-analysis of randomised clinical trials comparing FLACS and conventional phacoemulsification published just prior to this meeting (Sci Rep. 2015 Aug 13;5:13123) echoed the results I shared today. Importantly, however, an adequately powered long-term outcome study is still needed to determine the impact of FLACS on patient outcomes and quality of life after cataract surgery,” said Dr Nuijts, Professor of Ophthalmology, Maastricht University Medical Center+, The Netherlands.
Although the first FLACS case was performed almost seven years earlier, a search of literature published through to June 2015 identified only nine RCTs comparing FLACS and conventional phacoemulsification. Together with his colleagues Valentijn SC Webers MD, and Laura HP Wielders MD, Dr Nuijts extracted data from the papers to answer four key questions: 1) Does FLACS improve intraoperative parameters?; 2) What is the impact of FLACS on visual and refractive outcomes?; 3) How does FLACS affect the complication rate?; and 4) Does FLACS improve patient satisfaction and quality of life?
The evaluation of intraoperative parameters considered endpoints related to clear corneal incisions, capsulotomy, and nuclear fragmentation. Only one trial included data on clear corneal incisions morphology, and they showed a significant lower percentage of endothelial gaping and misalignment in the FLACS group compared to conventional phacoemulsification. Three trials evaluated capsulotomy circularity and two reported on IOL-capsule overlap, and their results consistently favoured FLACS. Data from two RCTs showed statistically significantly less IOL decentration and tilt (vertical and horizontal) when the femtosecond laser was used to create the capsulotomy.
Data on nuclear fragmentation were available from three RCTs for phacoemulsification energy and for EPT from four RCTs. FLACS had a benefit in the pooled analysis for both endpoints. There were also data to suggest that more efficient nucleus fragmentation translated into less corneal trauma, as assessed by changes in central corneal thickness early after surgery and endothelial cell counts.
Three RCTs included data on UDVA, and the pooled analysis found no significant differences between FLACS and conventional phacoemulsification at any follow-up interval through one year after surgery. Four RCTs reported on CDVA, and collectively their results showed a slightly better outcome with FLACS at one week and six months after surgery, but not at intermediate time points (one to three months).
Only two studies analysed refractive outcomes, and their results showed the mean absolute error was significantly smaller in the FLACS group at one to three months after surgery than in eyes that underwent conventional phacoemulsification.
Safety analyses focused on capsular tears and macular oedema. Dr Nuijts noted that authors of a comparative cohort case series (Ophthalmology. 2014;121:17-24) suggested that postage-stamp perforations and additional femtosecond laser aberrant pulses could lead to a higher rate of anterior capsule tears after FLACS compared with conventional phacoemulsification. In a follow-up report (J Cataract Refract Surg. 2015;41:47-52), the same authors reported a higher rate of anterior capsular tears using FLACS versus conventional phacoemulsification, however no significant difference in posterior capsule tear rates were found between groups.
In the review conducted by Dr Nuijts and colleagues, only two RCTs reported on anterior capsule tears, and the data showed that the rate with FLACS was low and not significantly different compared with conventional phacoemulsification. Posterior capsule tears were mentioned in two studies, but there were no cases of this complication in either trial. Two randomised trials also included macular thickness measurements from evaluations through follow-up to six months, and the data showed no significant difference between the two surgical groups.
CAVEATS TO CONSIDER
Although the review focused on randomised clinical trials, Dr Nuijts noted some potential limitations and weaknesses that leave the conclusions of the research open to discussion.
“The power calculations in some studies are not very realistic in describing expected differences, and most of the published studies are performed by consultants for the laser companies. In addition, technology evolves rapidly, and the initial results of these studies may be outdated by the introduction of updated technology. Therefore, in order to determine the impact of FLACS on quality of life and cataract surgery, adequately powered long-term outcome studies are needed,” added Dr Nuijts.
Rudy MMA Nuijts: email@example.com
Valentijn SC Webers: firstname.lastname@example.org
Laura HP Wielders: email@example.com