Article Text
PDF
Abstract
Aims To report 12-month outcomes of randomised controlled trial comparing conventional phacoemulsification surgery (CPS) with femtosecond laser-assisted cataract surgery (FLACS).
Methods This was a single-centre, prospective single-masked randomised case-controlled trial. Four hundred patients were randomised to CPS or FLACS with the LenSx platform (Alcon Laboratories Inc.). Visual acuity, refraction, central corneal thickness, endothelial cell loss (ECL), adverse events and quality of life outcomes, using EuroQOL 5-dimensions (EQ-5D-3 L) and cataract surgery patient-reported outcome measures (PROMs) questionnaires (Cat-PROM5), were recorded.
Results Two hundred and thirty four patients (58.5%) attended 12-month follow-up (116 FLACS, 118 CPS). Mean LogMAR unaided distance visual acuity) (±SD) was 0.12 (0.18) with FLACS and 0.13 (0.19) with CPS (p=0.68; 95% Confidence Interval [CI]−0.06,0.04). Mean spherical equivalent (SE) refraction was −0.1±0.6 diopters (D) with FLACS and −0.2±0.6 D with CPS (p=0.44; 95% CI −0.09, 0.21). Mean corrected distance visual acuity (±SD) was −0.01 (0.1) with FLACS and 0(0.1) with CPS (p=0.45; 95% CI −0.04,0.02). Two patients per group underwent YAG laser capsulotomy for posterior capsular opacification (p=1). Mean ECL (per mm2±SD) was 301±320 with FLACS and 228±303 with CPS (p=0.07; 95% CI −7.26, 153.26). Mean Cat-PROM scores (±SD) were −5.5 (2.6) with FLACS and −5.8 (2.5) with CPS (p=0.3; 95% CI 0.31,1.01). EQ5-3DL mean index score (±SD) was 0.92 (0.13) with FLACS and 0.89 (0.14) with CPS (p=0.1; 95% CI −0.1, 0.01). Vector analysis comparing manual limbal relaxing incisions (LRIs) and intrastromal femtosecond laser-assisted astigmatic keratotomies (iFAKs) showed a greater correction index (p=0.02; 95% CI 0.06 to 0.60) and smaller difference vector (p=0.046; 95% CI −0.54, −0.01) with iFAK.
Conclusions There were no differences in vision, refraction, adverse postoperative events or PROMs between FLACS and CPS groups at 12 months. iFAKs may provide more effective astigmatic correction compared to LRIs, 12 months postoperatively.
- Anterior chamber
- Aqueous humour
- Conjunctiva
- Cornea
- Eye (Globe)
- Clinical Trial
- Sclera and Episclera
Statistics from Altmetric.com
INTRODUCTION
It is more than a decade since femtosecond laser (FL) technology with its potential of automation and greater surgical precision was introduced into cataract surgery.1 Over this decade, it has continued to incite much research and commercial interest, while at the same time provoking controversy as to its perceived advantages and disadvantages.2– 7 Despite numerous studies, there is still ambiguity about whether femtosecond laser-assisted cataract surgery (FLACS) offers any clinical benefits over conventional phacoemulsification surgery (CPS). Certainly, given its associated financial costs, in its current technological form, it has been shown to be cost-ineffective within the public health sector.2 3
In a meta-analysis by Chen et al, results from nine randomised controlled trials (RCTs) (989 eyes) were pooled.4 They reported that while FLACS significantly reduced effective phacoemulsification time (EPT), there were no differences in central corneal thickness (CCT), endothelial cell count (ECC) or UDVA between FLACS and CPS after 1 week,2 and while the corrected distance visual acuity (CDVA) was better in FLACS at 1 week and 6 months, it was similar at 1–3 months, casting doubt over any true visual gains.4 More recently, Popovic et al, in a meta-analysis pooled result from 15 RCTs and 22 observational cohort studies (14 567 eyes), found no differences in postoperative UDVA, CDVA or refractive outcomes and although FLACS appeared to offer improvements in terms of EPT, ECC and CCT, it was, in their analysis, associated with a greater rate of posterior capsule rupture (PCR).5 A Cochrane review in 2016 by Day et al analysed data from 16 RCTs including 1638 eyes, rating all existing RCTs as having an unclear or high risk of bias, with most authored by investigators with financial interests related to FL manufacturers.6 They concluded, ‘There is currently not enough evidence to determine the benefits and harms of laser-assisted cataract surgery compared with standard ultrasound cataract surgery’.6 Most recently, a large RCT of 1476 eyes has been published and concluded that ‘FL was not superior to phacoemulsification in cataract surgery and, with higher costs, did not provide additional benefit over phacoemulsification for patients or healthcare systems’.7
For these reasons in 2016, we commenced our own independent RCT comparing FLACS and CPS,8 the aim of which was to complete the largest such RCT published at the time. Four hundred eyes of 400 patients were enrolled and perioperative and early postoperative data at 4 weeks reported, with no differences in UDVA, CDVA, refraction, CCT, ECC and patient-reported outcome measures (PROMs) at this time point between the treatment groups, although there appeared to be a reduction in the rates of PCR with FLACS.8 The aim of this study extension was to provide further comparative information between FLACS and CPS, by providing further data from our 400-patient cohort who were willing to attend the 12-month follow-up.
MATERIALS AND METHODS
This study was a prospective, single-centre (Guy’s and St Thomas’ Hospital NHS Foundation Trust (GSTT), London, UK) RCT (Clinicaltrials.gov registration number NCT02825693), approved by our local Research and Development department and Cambridge South Research Ethics Committee (reference 16/EE/0180) and adhering to the tenets of the Declaration of Helsinki. Patients were recruited from the cataract service at GSTT, between August 2016 and June 2017. Patient screening, recruitment and informed consent were obtained from all participants by members of the trial team (HR, VW) as per the trial protocol (Version 2.0, 18/05/2016; amendment Version 3.0, 28/10/2017). Inclusion and exclusion criteria are listed in box 1.
Only one eye per patient was enrolled in the study. Patients were randomised to receive CPS or FLACS in equal numbers using computer-generated random number tables (Excel 2013, Microsoft Corporation, WA, USA) just prior to being offered a date for surgery. Excel macros were used to perform the randomisation (this was concealed from the allocator) and then the allocation was locked with the patient’s research information to address allocation bias. All treatments were delivered by the National Health Service, free at the point of care. If a patient failed to attend a follow-up visit, they were contacted and offered another appointment. If they failed to attend this, they were considered lost to follow-up.
Cataract surgery
In the FLACS group, the femtosecond-laser platform (LensX, Alcon Laboratories Inc.) was used to perform capsulotomy, lens fragmentation and, in selected patients with preoperative astigmatism greater than 0.9 diopters (D), as measured by Scheimpflug tomography (Pentacam HD, Oculus Optikgeräte GmbH, Germany), intrastromal femtosecond laser-assisted astigmatic keratotomies (iFAKs).8
The parameters for iFAKs were determined by a previously reported nomogram9 with two differences. First, we elected to perform our main incisions on axis when possible, accounting for surgical access, whereas in the original study, they were consistently temporal, and although the original nomogram9 was intended to achieve up to 70% correction only, our target-induced astigmatism (TIA) was 100% correction. All iFAKs were 8.0 mm diameter paired symmetrical arcs and were limbal centred. The arcs were programmed to be intrastromal, non-penetrating, with a depth between 20% and 80% of corneal pachymetry as measured by the FL platform integral optical coherence tomography (OCT). Other iFAK parameters were as follows: 90-degree side-cut angle; horizontal and vertical spot spacing of 5 μm and 10 μm, respectively; pulse energy of 5 mJ. In cases in which either of the iFAKs overlapped with the surgeon’s planned manual wound, the main section was positioned more peripherally than the iFAK so that it would not be involved.
In the CPS group, patients with preoperative corneal astigmatism greater than 0.9 D underwent manual limbal relaxing incisions (LRIs), based on Donnenfeld’s nomogram via an online software program(’LRIcalculator’, Abbott Medical Optics Inc.; available at: https://www.lricalculator.com), using Pentacam HD (Oculus Optikgeräte GmbH, Germany) measurements and the individual surgeon’s surgically induced astigmatism (SIA). TIA was always 100% correction. Paired arcuate LRIs were always performed and when the surgeon’s preference was to operate on axis, the 2.4 mm main wound was positioned in the middle of the LRI. When anatomy or comfort dictated an off-axis approach, the surgeon’s SIA was used to modify the LRIs. A Mendez-style ring was used to mark the steep meridians at the start of the surgery. The LRI incision was made before the commencement of phacoemulsification using a 600 μm guarded knife. No corneal sutures were placed during the surgery.
All operations were performed under a local anaesthetic and all were unilateral. No other additional procedures were planned, other than AKs or iFAK for the reduction of corneal astigmatism.
Phacoemulsification was performed in all eyes using a gravity-fluidics torsional phacoemulsification system (Infiniti, Alcon Laboratories Inc.). Operations were performed by three surgeons who had completed at least 30 FLACS procedures (DO’B, VW, HR) before study commencement.
The default intraocular lens (IOL) used for in-the-bag placement was a monofocal hydrophobic acrylic IOL (Acrysof SA60AT, Alcon Laboratories Inc.). The MA60 lens (Alcon Laboratories, Inc.) was used as a sulcus lens if surgically indicated.
Data collection
Data collection was initially planned for the preoperative examination, the day of surgery and 4 weeks postoperatively and have been presented and published previously.8 For the purpose of this study extension, ethical approval was obtained for a further study visit and patients were recalled for 12-month follow-up. Primary outcome measure was UDVA. Secondary outcome measures were CDVA, refraction, ECC, astigmatic vectoral analyses, patient-reported outcome measures (PROMs) and rates of adverse events. Visual acuity and other assessments (corneal topography, specular microscopy, etc) were conducted by trained technicians and optometrists, masked to the participants’ treatment arm. All patients underwent slit-lamp examination and dilated (tropicamide 1% and phenylephrine 2.5%) funduscopy by the trial team (NS, VW, DO’B). Because of the nature of the intervention, neither the outcome assessors (NS, DO’B, VW, KN) nor the participant could be masked to the treatment arm. However, all clinical technicians, optometrists and nurses were masked to the intervention received. At the time of the follow-up appointment, optometrist or technician performing tests (VA, intraocular pressure[IOP], ECC, corneal topography, refraction) only received patient’s Case Report Form with the required investigations ticked in the appropriate boxes, and no information suggesting patients’ treatment arm. The research was overseen by an independent research and development department (R&D; St. Thomas’ Hospital, London, UK) who regularly inspected and reviewed research records and data. UDVA and CDVA were measured with a standard ETDRS backlit chart at 4 m (Precision Vision, IL, USA). Participants’ refractive errors were measured both with an auto-refractor (RK-510A, Nidek, Japan) and by subjective refraction performed by qualified optometrists. All results were reviewed by one investigator experienced in refraction (NS). Biometry was performed using partial coherence interferometry (IOL Master 500, Carl Zeiss Meditec AG, Germany). Corneal topography and CCT were determined using a Scheimpflug device (Pentacam HD, Oculus Optikgeräte GmbH, Germany), at all time points. Macular spectral-domain OCT was performed with a modular ophthalmic imaging platform (Spectralis, Heidelberg Engineering GmbH, Germany) at 1 month and then as per clinical need. ECC was measured with a specular microscope (EM-3000, Tomey GmbH (Europe), Germany) preoperatively, at 1 month and at 12 months. Visual comorbidities and risk factors for complications of cataract surgery were recorded prospectively. The risks for PCR were calculated for patients using a composite risk calculation system.10 In this paper, we present outcomes at 12 months.
Patient-reported outcomes and quality of life questionnaires
PROMs were assessed with the Cat-PROM5 tool consisting of five questions that provide a Rasch-calibrated psychometrically robust measure, specifically designed for cataract surgery, in which a higher score indicates greater visual disability.11 12 Quality of life outcomes were assessed using the EuroQOL EQ-5D-3 L questionnaire, consisting of two components: five questions about five dimensions of health-related quality of life (mobility, self-care, usual activities, pain/discomfort and anxiety/depression), which were scored as 1, 2, or 3 (1 meaning no problems and 3 meaning extreme problems). The five responses were then weighted and combined to create a summary index with values 0 to 1, where 1 indicates no problems. The visual analogue scale (VAS) was a continuous scale anchored by best imaginable and worst imaginable health, with values ranging from 0 to 100 (where 100 indicates best possible health). The EQ-5D-3 L was chosen because it is well recognised by public bodies (such as the National Institute for Health and Care Excellence in the UK) for comparative health economic analyses.13
Because changes in visual acuity or onset of ocular diseases/visual comorbidities in the fellow eye could have influenced quality of life questionnaires and PROMs between the 4- week visit and the 12-month visit, we also analysed the fellow eye data. Namely, we compared the visual acuity (UDVA and CDVA) in the fellow eye in those patients who attended at 12 months and in those who did not attend at 12 months (but attended at 4 weeks). We also compared the rate of occurrence of new comorbidities in the fellow eye, in both the FLACS group and the CPS group, between 4 weeks and 12 months.
Statistical analysis
Results were analysed as per intention to treat. Continuous data were reported using means ± SDs if the data appeared Gaussian. Binary data were reported as frequencies and percentages and evaluated with Fisher’s exact test. Student’s t-tests were used for parametric data with non-parametric equivalent tests used when data failed the parametric test assumptions. Statistical analysis was performed by two investigators (NS, HR) who, because of the nature of intervention, could not be masked to the participants' treatment arm. Data organisation and descriptive statistics were handled with Excel 2013 (Microsoft Corporation, WA, USA) and further statistical analyses with GraphPad (version 8.0; GraphPad Software, CA, USA). All statistical tests were two-sided with a significance level of 5% (p<0.05). Intraoperative or postoperative adverse events were defined as any event that involved unintentional trauma to an ocular structure, requiring additional treatment or having a negative effect on participants’ eyesight. The EQ-5D-3 L index scores were calculated using the method calibrated for the UK. The Rasch-calibrated Cat-PROM5 scores (logits) were calculated from the questionnaire responses in accordance with the developer’s instructions.11 12 UDVA was designated as the primary outcome at 12 months, with postoperative complications, refraction, CCT, endothelial cell loss (ECL), quality of life outcomes and patient-reported quality of vision results as secondary outcomes. A priori calculations for sample size indicated a total sample size of 370 to have an 85% chance of detecting a 0.1 difference in LogMAR visual acuity and assumption of σ=0.32 with α=0.05 and a two-tailed analysis.
RESULTS
Baseline group characteristics
Originally, 427 patients were recruited to the study, with 27 patients withdrawing before surgery and 400 eyes of 400 patients undergoing cataract surgery (200 FLACS, 200 CPS) between November 2016 and June 2017 (figure 1). Three hundred and ninety-one patients (89%) patients attended their 4-week follow-up, the results of which have been previously published8 (figure 1). All 400 patients were invited for 12-month follow-up by letter and an appointment was subsequently organised by telephone of which 234 patients (58.5%) agreed and consequently attended (116 patients from the FLACS group and 118 from the CPS group) (figure 1). The patient demographics and full preoperative and 4 -week postoperative baseline data for the 234 patients attending 12-month follow-up, and those that did not are shown in tables 1 and 2, with no significant differences, except for preoperative axial length (AL), both between the two treatment arms and those who attended and who did not.
Preoperative baseline characteristics and 4-week data of patients who attended compared to those who did not attend at 12 months
Baseline characteristics of the two treatment arms for patients that attended follow-up at 12 months (n=234)
Consolidated Standards of Reporting Trials flowchart of participant numbers through the study.
Twelve months visual, refractive, ECC, CCT and PROMs results are shown in table 3 and figure 2. There were no differences in UDVA, CDVA, change in CCT (compared to preoperatively), ECC loss (compared to both preoperatively and 1 month postoperatively), residual refractive cylinder, SE refractive error from target refraction (both arithmetic and absolute) and changes in PROM indices (Cat-PROM scores, EQ5-3D-3L index scores and VAS).
Postoperative results
Visual and refractive outcomes in the FLACS group (top row; 113 eyes) and the CPS group (bottom row; 115 eyes) for patients with targeted refractive outcome for emmetropia. CPS, conventional phacoemulsification surgery; FLACS, femtosecond laser-assisted cataract surgery.
Rates of postoperative adverse events are shown in table 4. There were no differences in rates of Nd: YAG laser capsulotomies or other documented postoperative complications at 12 months.
Postoperative complications (12 months)
From the original cohort of 400 eyes, 106 patients (26.5%) were identified as having corneal astigmatism of >0.9 D on Pentacam HD tomography (Oculus Optikgeräte GmbH, Germany)and were offered either iFAKs or LRI, depending on their allocation group. One patient in the FLACS group (1.8%) and 1 patient in the CPS group (1.9%) opted against additional astigmatic surgery. Accordingly, 53 patients underwent iFAK in the FLACS group and 51 LRIs in the CPS treatment arm. At 12 months, 36 patients (68%) from the iFAK group and 33 patients (65%) from the LRI group returned for follow-up. Corneal astigmatic outcomes at 12 months were analysed using the Alpins vector method14 (table 5). We also compared corneal astigmatic outcomes at 4 weeks to those at 12 months in each group to evaluate the stability of the two modes of corneal astigmatism correction (table 6A and B). TIA (equivalent to preoperative corneal astigmatism) was similar in both groups (table 5) suggesting that both groups were similar with regard to the amount of corneal astigmatism we intended to treat. At 12 months, there was a trend towards achieving greater astigmatism correction in the iFAK group, but this was not statistically significant (table 5). However, correction index (CI) was higher in the iFAK group (p=0.02), suggesting that the patients who received LRIs were more undercorrected than those who received iFAKs. At 12 months, the mean difference vector (DV; arithmetic; equivalent to postoperative corneal astigmatism) was also significantly less in the iFAK group (p<0.05) (table 5), suggesting that patients in this group had more astigmatism corrected. This is also reflected in the value of index of success (IOS), which was closer to ‘zero’ (ideal value) in the iFAK group, but this did not reach statistical significance (table 5).
Astigmatic vectoral analyses pre-op vs 12 months
There was no statistically significant change in any of the vectoral astigmatic indices in either group, between 4 weeks and 12 months (table 6A and B), suggesting relative stability of both astigmatic corrections. However, while the effect of LRI slightly reduced from 4 weeks to 12 months, the effect of iFAK increased slightly (SIA vector magnitudes; table 6A and B).
Astigmatic vectoral analyses at 4 weeks and 12 months post-op in the iFAK group
Astigmatic vectoral analyses at 4 weeks and 12 months post-op in the LRI group
With regard to the fellow eye, UDVA and CDVA were not statistically significantly different between the group that attended at 12 months and the group that did not attend at 12 months, but attended at 4 weeks, both preoperatively and at 4 weeks follow-up (table 7).
Fellow eye visual acuity in the group that attended at 12 months and the group that did not attend at 12 months
The incidence of new fellow-eye co-morbidities/diseases between 4 weeks and 12 months was not statistically significantly different between the FLACS group and the CPS group (table 8). Seven patients in the FLACS group developed new comorbidities (six cataracts, one visually significant posterior capsular opacification [PCO]) and eight patients in the CPS group developed new comorbidities (three cataracts, one visually significant trauma, three primary open angle glaucomas and one visually significant PCO).
The rate of onset of comorbidities in the fellow eye at 4 weeks and at 12 months in the FLACS group and the CPS group
DISCUSSION
There is still lack of evidence that, despite its purported advantages of greater surgical precision, FLACS has any clinical advantage over CPS. Indeed, this has been supported by published meta-analyses,4 5 a Cochrane review6 and our own 400-patient RCT.8 The recently published Economic Evaluation of FLACS trial recruited 907 patients (1476 eyes) of which 870 patients’ eyes were analysed (704 in the FLACS group and 685 in the CPS group).7 The authors concluded that FLACS was not superior to CPS, as it did not provide an additional benefit over CPS for patients in terms of outcomes and it incurred higher costs.7 Full results of another large study, the FACT trial, the protocol of which was published in 2015 and which aimed to recruit 808 eyes and follow the participants up to 12 months postoperatively, will hopefully be published soon.15
As discussed above, our group has reported results of 400 patients randomised to either FLACS or CPS8 and concluded no real clinical advantage of FLACS over CPS for routine large-volume cataract surgery in a public sector setting. We evaluated postoperative visual acuity, refraction, CCT, ECL, central foveal thickness and perioperative complications.8 Results were collected at 4 weeks postoperatively and no statistically significant difference was found in any of the parameters tested, except for PCR rate, which was just statistically significant and may have been due to type 2 statistical error.
In this paper, we present 12-month results from the same patient cohort as our original study,8 which, despite only 58.5% of patients agreeing to return for follow-up, is still one of the largest trials to present long-term data. We evaluated the same parameters as listed above except the central foveal thickness. Our results indicated that both groups had excellent visual and refractive outcomes at 12 months with no statistically significant difference in any of the tested parameters (table 3, figure 2). The rate of Nd:YAG laser capsulotomies for significant PCO was similar in both groups and no other reported adverse events were different between the groups (table 4). PROMs as tested with three validated scales were all similar and not statistically different between the groups. Although validated cataract surgery-specific PROMs at 1 month postoperatively have been reported,8 this is the first time the same PROMs at 12 months postoperatively have become available, when comparing FLACS and CPS in an RCT setting. In contrast with other studies, we did not find that FLACS resulted in more predictable refractive outcomes than CPS (table 3, figure 2).16– 18
Importantly, we demonstrated that the change in fellow eye UDVA and CDVA in those who attended at 12 months and those who did not attend at 12 months was not statistically significantly different both pre-op and at 4 weeks (table 8). In addition, the rate of onset of new visually significant comorbidities in the fellow eye between 4 weeks and 12 months was not significantly different between the FLACS group and the CPS group (table 8). Although the quality of life and PROMs outcomes at 12 months should therefore not be affected by the fellow eye status, one must still consider that the low follow-up rate at 12 months limits these results and they perhaps may not be applicable to the standard cataract population.
In our previous report, we found anterior capsular tear rate to be greater in the FLACS group than in the CPS group (3% vs 1.5%).8 Similarly, in a prospective comparative cohort study of 1626 patients undergoing FLACS or CPS, Abell et al 18 also showed a higher rate of anterior capsular tears in FLACS (1.87% vs 0.12%, p=0.0002), with scanning electron microscopy of the anterior capsule in the FLACS group showing an irregular capsule margin as well as misplaced laser pits, although it should be noted that FLACS technology has improved since this paper was published.19 Although we found two cases of anterior capsule phimosis in the CPS groups and none in the FLACS group, it is difficult to interpret this data in view of the significant dropout rate at 12-month follow-up. It is therefore unclear whether this might suggest a long-term advantage in this respect of the FL-performed capsulorhexis over manually performed ones and merits further investigation.
In our patient cohort, corneal stigmatism greater than 0.9 D on tomography was corrected either with iFAK or with LRIs, both of which have previously been found to be effective in reducing astigmatism after cataract surgery.9 20 A previous report by our group analysing astigmatic outcomes in both treatment arms indicated that iFAK group had a greater CI and smaller DV than the LRI group, at 4 weeks postoperatively.21 Our 12-month data similarly shows that the CI was significantly greater in the iFAK group and that the DV was significantly less in the iFAK group (table 5). Despite this being a smaller cohort compared to 4 weeks, the patients in the two groups were comparable in terms of TIA (table 5). Nevertheless, it is difficult to make conclusions applicable to standard cataract population from this data, in view of the significant dropout rate at 12 months follow up.
When we compared corneal astigmatism between 4 weeks and 12 months in each group, we found that the Alpins’ indices were comparable (table 6A and B), suggesting stability of both methods over this period. Interestingly, the mean magnitude of the SIA at 12 months increased in the iFAK group (~0.15 D) and reduced in the LRI group (~0.15 D), but neither change was statistically significant (table 6A and B). Similarly, the CI from 4 weeks to 12 months reduced in the LRI group and increased in the iFAK group (table 6A and B). An increase in CI from 2 months to 2 years with FAKs has been found in another study, although of retrospective design and using trans-epithelial rather than intrastromal FAKs,22 by Chen et al. They also documented that the mean SIA vector magnitude increased by 0.07 D between 2 months and 2 years postoperatively,22 while Day and Stevens23 found that the astigmatism correction effect in their iFAK group regressed by ~0.1 D at 6 months post-operatively, but this was similar to the control group that did not receive iFAKs. Conversely, LRIs have been known to have a maximal effect early after surgery and then to regress over time,24 which is what we also demonstrated in this study. Such findings are of great interest and might suggest better stability of astigmatic correction with iFAKs and merits further investigation with larger patient cohorts with higher follow-up attendance rates.
One limitation of this present study is the lack of complete follow-up at 12 months with only 58.5% of the original cohort attending. Hence, the applicability of our findings may be limited in terms of how it can be applied to a standard cataract surgery population. Attempts to contact all patients to attend for 12-month follow-up by telephone and letter were undertaken but unfortunately, not all wished to or could attend. It is of note, however, that there were no statistically significant differences in the baseline or 4-week data, except for AL (table 1), suggesting that the group that attended at 12 months had a slightly higher AL perhaps potentially making this group more at risk of intraoperative and postoperative complications, although this was not reflected in the reported complication rates. Alternatively, this may simply represent a type 1 error.
In summary, our results confirm those of previous research that is that there is no clinical advantage with FLACS over CPS. Therefore, in addition to the previous evidence that there is no economic benefit with FLACS over CPS,2 3 it is difficult to justify using FLACS in its current technological form in a clinical setting unless further evidence arises to support its usage economically and clinically. However, heavy financial investment into FLACS platforms and market forces promoting its use may continue its usage across the world, as long as consumers are willing to pay the premium for the latest technology.
Box 1 Inclusion and exclusion criteria for enrolment in the trial
Inclusion criteria
Reduced visual acuity or visual symptoms attributed to the presence of cataract in one or both eyes by the examining ophthalmologist or must require cataract surgery on clinical grounds other than visual symptoms.
Willing to attend follow-ups 3 to 4 weeks after cataract surgery.
Sufficient English language for informed consent and completion of the patient-reported outcome questionnaires.
Exclusion criteria
Age below 18
Already enrolled in another study
Clinical contraindications for femtosecond laser-assisted cataract surgery, such as significant corneal opacities
Small pupils (<4.0 mm) after pharmacological dilatation
Patients unable to lie sufficiently flat to be positioned underneath the laser machine.
REFERENCES
Footnotes
Contributors NS: design, data collection, analysis and interpretation of data, drafting the article, revising the article. HR: design, analysis and interpretation of data, drafting the article, revising the article. VKW: design, data collection, analysis and interpretation of data, drafting the article, revising the article. J-POL: analysis and interpretation of data, drafting the article, revising the article. KN: data collection, drafting the article, revising the article DPO’B: design, analysis and interpretation of data, drafting the article, revising the article.
Competing interests Professor O’Brart has held non-commercial grants from Alcon, Rayner and Avedro. Harry Roberts has undertaken consultancy work for Alcon in the past 12 months.
Patient consent Full informed consent was obtained from all participants.
Ethics approval Cambridge South Research Ethics Committee (reference 16/EE/0180).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information.
Linked Articles
- At a glance