A Systematic Review: Benefits and Harms of Femtosecond Laser-Assisted Cataract Surgery
Cataract surgery is a frequently performed operation in the VA healthcare system, with more than 49,000 performed in 2012. As a result, the VHA National Surgery Office has been tasked with making a recommendation regarding whether femtosecond lasers provide appropriate cost-benefit and risk-benefit ratios to support implementation for cataract surgery in VA. This evidence review examined the potential benefits and adverse effects related to femtosecond laser-assisted cataract surgery (FLACS) relative to conventional cataract surgery, and will aid VA leadership in determining policy for use of this technology. In addition, meta-analyses were conducted of two commonly reported outcomes in femtosecond laser (FSL) and conventional cataract surgery procedures: corrected distance visual acuity (CDVA), and effective phacoemulsification time (EPT).
The VA Evidence-Based Synthesis Program located in Portland, OR reviewed 468 titles and abstracts from an electronic search of the literature, as well as 436 additional references through manual searching of reference lists, input from technical advisors, and reviewing conference proceedings of ophthalmalogic societies for recently unpublished or ongoing studies. After applying inclusion/exclusion criteria at the abstract level, 16 articles met review criteria. Based on this evidence, results are presented in the Summary, which is followed by several key questions providing more detailed information.
In this review, FLACS appears to be comparable to conventional cataract surgery, though the evidence base is limited. For example, the evidence for the relative benefit of FLACS was limited by reliance on small to moderately-sized prospective cohort studies, nearly all of which had stated financial conflicts of interest. Adverse events unique to FLACS involved difficulties in laser docking or patient suitability for the procedure. Many patients were excluded from the FSL treatment groups for orbital, corneal, cataract density, or medical comorbidities. Comparative adverse events in FLACS and conventional surgery were found to be similar for intraocular lens (IOL) positioning, corneal thickness, macular edema, and residual refractive error. A few studies reported mixed results of the effect of surgical experience on the incidence of FLACS adverse events. Quality of life and cost-effectiveness outcomes were not reported.
Key Question #1
What is the evidence that FLACS is associated with better outcomes than conventional cataract surgery?
Nine studies addressing the comparative effectiveness of FLACS versus conventional surgery were identified, including three small to medium-sized randomized controlled trials. However, six of these studies (and all three RCTs) were conducted at one university in Hungary, with all surgeries performed by the same surgeon using the Alcon LenSx laser. Overall, results show:
- Low evidence of comparative benefit of FLACS.
- No significant differences noted between groups for CDVA outcomes.
- EPT outcomes were mixed, with results either comparable between FSL and conventional cataract surgery groups, or favoring FSL groups.
- No studies addressed quality of life measures.
Key Question #2a
What are the adverse effects that have been reported for FLACS?
Seven studies were identified addressing adverse effects unique to FLACS. Sample sizes in these studies ranged from 25 to 1,300 patients, with follow-up periods extending from immediately following the procedure to three months post-operative. Results show:
- Five studies reported difficulties related to the laser interface with the ocular surface (including the orbital structures).
- Two studies measured intraocular pressure (IOP) fluctuation during FLACS procedures. A small proportion of patients experienced suction breaks, second docking attempts, and aborted procedure adverse events. FSL application was also associated with an increase in IOP.
- Overall, investigators found moderate to low strength of evidence for adverse events with methodological concerns from enrollment criteria used for FSL surgery groups.
Key Question 2b
What is the risk of adverse effects from FLACS compared to the risk associated with conventional cataract surgery?
Nine studies addressed the adverse effects of FLACS compared to conventional cataract surgery. Sample sizes in these studies ranged from 25 to 400 patients, with follow-up periods extending from one week to one year. Results show:
- Five studies reported, variously: capsulotomy configuration, position and the resultant effects on IOL decentration and refractive outcomes. Two of these studies reported post-operative corneal edema by measuring either corneal thickness or corneal endothelial cell loss.
- An additional two studies compared post-operative macular thickness and morphology, as measured by optical coherence tomography (OCT). The FSL and control groups were similar for post-operative corneal thickness and macular edema measurements, with corneal endothelial cell loss decreased in the FSL group in one study.
- Overall, investigators found moderate to low strength of evidence for comparative adverse events with methodological concerns from enrollment criteria used for the FSL and conventional surgery groups.
Key Question #3
What is the evidence that the experience of the surgeon is associated with adverse effects of FLACS?
Three studies reported outcomes relevant to the experience of the surgeon in performing the FLACS procedure. Sample sizes in these studies ranged from 200 to 1,300 patients, with follow-up periods extending from two weeks to three months. Overall, results show:
- One study found no significant differences between outcomes for initial and subsequent groups of patients undergoing FLACS, while two studies from the same team of researchers found significantly fewer complications associated with greater experience with FLACS.
- There were methodological concerns from enrollment criteria used for the FSL and conventional surgery groups.
Greater numbers of randomized control trials (RCTs) with larger sample cohort sizes are desirable to allow detection of the relative risks of rare events. Studies that are sufficiently powered and well-designed should be insulated from the device manufacturers to eliminate potential bias. Head-to-head trials between FSL platforms should assist in informing potential users of their relative risks and benefits. Studies from groups other than those few included in this review should provide a more global perspective of FLACS. The applicability of the FSL technology to the overall cataract population has not been explored by the eligible studies in this review. Further studies regarding the suitability of FSL for patients with the comorbidities found in the VA population (i.e. dense cataracts, glaucoma, corneal pathology), as well as studies assessing the costs relative to benefits expected from FLACS and conventional surgery will be key to determining the feasibility of widespread adoption of this procedure.
A cyberseminar session on this ESP Report will be held on April 29, 2014 at 2:00pm (ET). To register, go to the HSR&D Cyberseminar web page.
This report is a product of VA/HSR&D's Quality Enhancement Research Initiative's (QUERI) Evidence-Based Synthesis Program (ESP), which was established to provide timely and accurate synthesis of targeted healthcare topics of particular importance to VA managers and policymakers — and to disseminate these reports throughout VA.
Quiñones A, Gleitsmann K, Freeman M, Fu R, O'Neil M, Motu'apuaka M, Kansagara D. Benefits and Harms of Femtosecond Laser-Assisted Cataract Surgery: A Systematic Review. VA-ESP Project #05-225;2013.
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