Outcomes of laser refractive surgery for myopia

Interleukin 12 in the Acute Phase of the Immune Response after Excimer Laser Treatment

BACKGROUND AND OBJECTIVES

The aim of the research was to investigate the differences in the concentrations of IL-12, IL-4, IL-10, and IFN-γ in tears after LASIK and PRK procedures.

MATERIALS AND METHODS

The study included 68 myopic eyes up to -3.0 D refractive spherical equivalent, divided into two groups: Group 1 LASIK (n = 31) and Group 2 PRK (n = 37). Three tear samples were taken from each eye: immediately before the procedure (t₀), 1 h after the procedure (t₁), and 24 h after the procedure (t₂). The concentrations of IL-12p70, IL-4, IL-10, and IFN-γ in the tear samples were determined by flow cytometry. Participants were not taking anti-inflammatory therapy 24 h after the procedure.

RESULTS

IL-4 levels 1 h after treatment did not differ between LASIK and PRK (p = 0.990), while 24 h after PRK there was a significant decrease in IL-4 levels (p < 0.05), but not after LASIK (p = 0.476). In both the LASIK (p < 0.05) and PRK (p < 0.05) groups, there is an increase in IL-10 concentrations 1 h after treatment, which persists 24 h after LASIK (p < 0.05) but not after PRK (p = 0.081). There is an increase in IL-12p70 concentration 1 h after treatment in both the LASIK (p < 0.001) and PRK groups (p < 0.001). There is also an increase in IL-12p70 concentration 24 h after PRK (p < 0.005), but not after LASIK (p = 0.775).

CONCLUSIONS

IL-4 concentration shows a significantly higher value in the LASIK group than in the PRK group after 24 h. IL-10 and IL-12p70 levels increase one hour after surgery in both groups. After 24 h, the IL-10 levels remain elevated in the LASIK group, and the IL-12p70 levels remain elevated in the PRK group. Thus, LASIK and PRK procedures show different inflammatory dynamics.

Assessment of the biometric modifications of the eye in LASIK during suction

PURPOSE

To study the biometric modifications of the eyeball during suction in Laser assisted in Situ Keratomileusis (LASIK).

METHODS

Observational and cross-sectional study. We studied 43 patients who underwent surgery for myopia and myopic astigmatism. Mean age was 38.3 ± 11.5 years, and 19 were female (44.2%). Conventional LASIK surgery with a manual microkeratome was performed. Before and during the suction maneuvre the following parameters were measured using an 11 Mhz biometric probe: aqueous depth (AQD), lens thickness (LT), vitreous cavity length (VCL) and axial length (AXL). Paired t-test was used to compare the biometric measurements before and during suction.

RESULTS

The mean spherical equivalent refractive error was -4.5 ± 2.3 diopters. During suction, the AQD did not change significantly (p = 0.231). However, AXL and VCL increased by 0.12 mm and 0.22 mm respectively (p = 0.039 and <0.01) and LT decreased by 0.20 mm (p < 0.01). AXL increased in 42% of the eyes and decreased in 16%, VCL increased in 70% of the eyes and decreased in 9%, and the LT was reduced in 67% of the eyes.

CONCLUSIONS

Suction maneuvres during LASIK surgery produce changes of little magnitude in the eye globe, mainly a decrease in LT and an increase in VCL and AXL. Therefore, these modifications are expected to produce minimal anatomic alterations.

Analysis of corneal biomechanical properties 25 years after myopic photorefractive keratectomy

PURPOSE

To evaluate corneal biomechanical changes using Corvis ST in patients treated with photorefractive keratectomy (PRK) 25 years ago.

METHODS

In this study, 32 post-PRK and 38 normal eyes underwent Corvis ST (CST) assessments. The measured CST factors were: time of highest concavity (HC), time of applanation 1 (AT1), time of applanation 2 (AT2), length of applanation 1 (AL1), length of applanation 2 (AL2), velocity of applanation 1 (AV1), velocity of applanation 2 (AV2), deformation amplitude (DA), peak distance (PD), integrated radius (IR), Ambrosio relational thickness horizontal (ARTh), stiffness parameter at first applanation (SP-A1), DA ratio (2 mm), Belin/Ambrosio enhanced ectasia display (BAD) and corneal biomechanical index (CBI).

RESULTS

The mean [± standard deviation (SD)] age was 51.4 ± 7.36 years in PRK, 51.4 ± 3.62 in control group. PRK was performed 24.69 ± 1.78 years ago. ARTh, SP-A1, AT1, AL1, and AL2 were lower in PRK. PD, AT2, DA ratio (2 mm), and IR were statistically higher in PRK (P < 0.01). In PRK and control group the mean value of CBI was 0.91 ± 0.11 and 0.50 ± 0.27 (P < 0.001), and mean value of BAD was 3.34 ± 1.53 and 1.1 ± 0.70 (P < 0.001). In PRK 71.9% of eyes were classed "high risk CBI plus diseased BAD" and 25% remained in the "high risk CBI and normal BAD" group.

CONCLUSIONS

In this study, most of the post-PRK eyes which were clinically and topographically normal were classified as "high risk CBI plus diseased BAD" and had significantly worse CBI and BAD values than the control group. This leads to the conclusion that CBI and BAD alone are not appropriate to evaluate post-PRK ectasia.

Evaluating Intraocular Pressure After Myopic Photorefractive Keratectomy: A Comparison of Different Tonometers

PRCIS

All devices evaluated in this study showed a significant underestimation in intraocular pressure (IOP) measurement after myopic photorefractive keratectomy (PRK), Goldmann tonometer more than others. Corneal biomechanics indicated a different influence on the different kinds of tonometry.

PURPOSE

The aim was to investigate the reliability of Goldmann applanation tonometry (GAT), rebound tonometry (RT), ocular response analyzer (ORA), Corvis ST (CST), and dynamic contour tonometry (DCT) in IOP evaluation after myopic PRK.

MATERIALS AND METHODS

One eye of 145 patients who underwent myopic PRK for a refractive defect ranging from -10.25 to -0.50 D (mean -4.69±2.00 D) was included in this retrospective comparative study. A complete eye visit with corneal tomography and IOP measurement with GAT, DCT, ORA, RT, and CST was performed before surgery and at 1, 3, and 6 months follow-up. Values provided by each device were tested and compared at each follow-up. Correlation analyses were run between changes in IOP and the corneal, morphologic and biomechanical parameters were measured after PRK.

RESULTS

GAT, DCT, ORA, RT, and CST showed a significant (P<0.01) underestimation of IOP at 6 months follow-up. GAT showed the greatest underestimation (-14.1%) and stronger correlations with corneal deformation parameter changes, whereas ORA, DCT, and RT appeared to be less conditioned by these variations. At 6 months follow-up DCT, ORA, RT, and CST provided IOP values with nonsignificant differences compared with GAT before PRK.

CONCLUSIONS

Each tested tonometer showed a significant IOP underestimation after myopic PRK. As this was most observed with GAT compared with all devices, we suggest DCT, ORA, RT, or CST to evaluate IOP in these patients following surgery.

Preoperative Predictors for Acute Pain After Photorefractive Keratectomy

PURPOSE

The aim of this study was to identify preoperative predictors for the occurrence of early severe postoperative pain in patients undergoing photorefractive keratectomy (PRK). The implementation of preoperative screening methods may facilitate more specific or aggressive pain therapies specifically targeted to individuals at a high risk of experiencing severe postoperative pain.

METHODS

This was exploratory research that included patients who underwent PRK. Before PRK, patients were administered a sociodemographic questionnaire, the Pain Catastrophizing Scale, and the State-Trait Anxiety Inventory and underwent corneal sensitivity and conditioned pain modulation (CPM) tests. Post-PRK pain was assessed using a pain intensity visual analog scale (VAS), and the short-form McGill Pain Questionnaire (SF-MPQ) was completed 21 days before PRK and 1, 24, 48, and 72 hours after PRK. Spearman correlations were calculated for pain scores and preoperative predictors.

RESULTS

This research included 34 eyes of 34 patients. Preoperative corneal sensitivity was positively correlated with post-PRK pain scores as assessed by VAS and SF-MPQ (rho = 0.39 and rho = 0.41, respectively, P < 0.05). No correlations were found between Pain Catastrophizing Scale, State-Trait Anxiety Inventory, and CPM scores and post-PRK pain scores (P > 0.05).

CONCLUSIONS

Abnormal presurgical corneal sensitivity was a protective marker for severe pain after PRK, while scores as assessed by VAS and SF-MPQ and CPM were not related to postoperative pain.

Presbyopia-Correcting Intraocular Lenses Implantation in Eyes After Corneal Refractive Laser Surgery: A Meta-Analysis and Systematic Review

Purpose

To assess the efficacy, safety, and predictability of presbyopia-correcting intraocular lenses (IOLs) in cataract patients with previous corneal refractive surgery.

Methods

A systematic literature search was performed to identify studies evaluating the clinical outcomes of presbyopia-correcting IOLs implantation in cataract surgery after laser refractive surgery. Outcomes were efficacy, safety and predictability parameters.

Results

The authors identified 13 studies, involving a total of 128 patients and 445 eyes. Presbyopia-correcting IOLs were effective at improving distance, intermediate and near visual acuity aftercataract surgery. The proportion of post-laser surgery eyes with uncorrected distance visual acuity (UDVA) ≥ 20/25 was 0.82 [95% confidence interval (CI), 0.74-0.90] and the pooled rates of spectacle independence at near, intermediate, and far distances were 0.98 (95% CI, 0.94-1.00), 0.99 (95% CI, 0.95-1.00) and 0.78 (95% CI, 0.65-0.94) respectively. The percentage of participants who suffered from halos and glare was 0.40 (95% CI, 0.25-0.64) and 0.31 (95% CI, 0.16-0.60), respectively. The predictability had a percentage of 0.66 (95% CI, 0.57-0.75) and 0.90 (95% CI, 0.85-0.96) of eyes within ±0.5 diopters (D) and ±1.0 D from the targeted spherical equivalent.

Conclusions

Presbyopia-correcting IOLs provide satisfactory results in terms of efficacy, safety and predictability in patients with previous corneal refractive surgery, but have a higher risk of photopic side effects such as halos and glare.

Single-Step Transepithelial Photorefractive Keratectomy in Low to Moderate Myopia: A One-Year Follow-Up Study

Aim

To evaluate predictability, safety, efficacy, and visual outcome of StreamLight. ™ (SL.), the newly released single-step transepithelial photorefractive keratectomy platform by Alcon WaveLight™ (WL).

Methods

In this prospective cohort study, photorefractive keratectomy (PRK) was conducted on 500 eyes of 250 patients seeking myopic refractive vision correction. The new single-step transepithelial PRK method was applied, using the SL. platform installed in the WL. Ex 500 excimer laser machine. Patients were followed up to monitor intensity and duration of postoperative pain, as well as speed of epithelial healing in the early post-operative period and visual acuity, postoperative refraction and development of postoperative haze for one year post-operatively.

Results

Average pain duration was 1.5 days, and the mean pain intensity score on a scale of 0–10 was 3.74 + 1.51. Mean postoperative spherical equivalence was 0.01 ± 0.38 D, and the final postoperative uncorrected distance visual acuity (UCDVA) was 20/20 in 98% of eyes included in this study. None of the eyes lost more than one Snellen chart line or developed visually significant postoperative haze during the follow-up period.

Conclusion

The new SL. platform for transepithelial PRK is a safe, accurate platform, offering an easier early post-operative recovery, with no compromise in final visual outcome.

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Analysis of Corneal Distortion after Myopic PRK

The purpose of the study is to evaluate the corneal biomechanical properties (CBP) and their behaviors after myopic refractive surgery both with Ocular Response Analyzer (ORA) and Corvis ST (CST). This retrospective study included 145 eyes of 145 patients with a mean age of 33.13 ± 9.24 years, who underwent myopic photorefractive keratectomy (PRK) for a refractive defect, measured as spherical equivalent, of mean −4.69 ± 2.04 D and have been evaluated before surgery and at 1, 3 and 6 months follow-up. Corneal hysteresis (CH) and corneal resistance factor (CRF) values significantly decreased after 1 month and remained statistically stable during further follow-ups. CST parameters had a different evolution: only second applanation time (AT2) differences showed a significant variation after 1 month that did not statistically change over time. Highest concavity deformation amplitude (HCDA), highest concavity peak distance (HCPD), first applanation time (AT1) and velocity (AV1) showed continuous significant differences both after 3 and after 6 months. This study suggests that after central surface ablation surgery, such as myopic PRK, corneal shape is remodeling, and its deformation parameters are going to change even at 6 months follow-up. This indicates that it should be important to evaluate refractive surgery patients during a longer follow-up because this could allow earlier diagnosis and better management of late-onset complications.

Visual recovery after small incision lenticule extraction (SMILE) in relation to pre-operative spherical equivalent

PURPOSE

To assess visual recovery after small incision lenticule extraction (SMILE) in relation to pre-operative spherical equivalent.

METHODS

Two hundred fourteen eyes of 107 patients were enrolled. Following surgery, patients were examined pre-operatively, 1 day, 2 weeks, 1 month and 3 months later. High myopia was defined as pre-operative spherical equivalent ≤ - 5 D. A linear mixed-effects model was used.

RESULTS

Mean ± standard deviation pre-operative spherical equivalent was - 5.30 ± 1.36 D that reduced significantly to 0.04 ± 0.70 D (p < 0.001) at 1 month and - 0.02 ± 0.66 D (p < 0.001) at 3 months. Mean pre-operative LogMAR uncorrected distance visual acuity ± SD was 0.97 ± 0.09 that improved significantly to 0.04 ± 0.06 at 2 weeks (p < 0.001), 0.01 ± 0.04 at 1 month (p < 0.001) and 0.01 ± 0.04 at 3 months (p < 0.001). Eighty-eight eyes (41.2%) had uncorrected distance visual acuities of 0.0 at 1 day, 154 eyes (72.0%) at 2 weeks,194 eyes (90.7%) at 1 month and 199 eyes (93.0%) at 3 months. Significantly more eyes with low myopia (> - 5 D) achieved acuities of 0.0 at 1 day and 2 weeks (p = 0.041 and p < 0.001). Post-operative acuities were not associated with refractive targets, laser cut energy settings or other variables. Two hundred nine eyes (97.7%) were within ± 0.5 D of target and 213 eyes (99.5%) were within ± 1 D.

CONCLUSIONS

SMILE for low myopia had faster visual recovery in the early post-operative period with no significant differences between groups detected by 1 and 3 months.

Laser-assisted in-situ keratomileusis (LASIK) with a mechanical microkeratome compared to LASIK with a femtosecond laser for LASIK in adults with myopia or myopic astigmatism

BACKGROUND

Laser-assisted in-situ keratomileusis (LASIK) is a surgical procedure that corrects refractive errors. This technique creates a flap of the outermost parts of the cornea (epithelium, bowman layer, and anterior stroma) to expose the middle part of the cornea (stromal bed) and reshape it with excimer laser using photoablation. The flaps can be created by a mechanical microkeratome or a femtosecond laser.

OBJECTIVES

To compare the effectiveness and safety of mechanical microkeratome versus femtosecond laser in LASIK for adults with myopia.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2019, Issue 2); Ovid MEDLINE; Embase; PubMed; LILACS; ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We used no date or language restrictions. We searched the reference lists of included trials. We searched the electronic databases on 22 February 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of LASIK with a mechanical microkeratome compared to a femtosecond laser in people aged 18 years or older with more than 0.5 diopters of myopia or myopic astigmatism.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 16 records from 11 trials enrolling 943 adults (1691 eyes) with spherical or spherocylindrical myopia, who were suitable candidates for LASIK. Five hundred and forty-seven participants (824 eyes) received LASIK with a mechanical microkeratome and 588 participants (867 eyes) with a femtosecond laser. Each trial included between nine and 360 participants. In six trials, the same participants received both interventions. Overall, the trials were at an uncertain risk of bias for most domains. At 12 months, data from one trial (42 eyes) indicates no difference in the mean uncorrected visual acuity (logMAR scale) between LASIK with a mechanical microkeratome and LASIK with a femtosecond laser (mean difference (MD) -0.01, 95% confidence interval (CI) -0.06 to 0.04; low-certainty evidence). Similar findings were observed at 12 months after surgery, regarding participants achieving 0.5 diopters within target refraction (risk ratio (RR) 0.97, 95% CI 0.85 to 1.11; 1 trial, 79 eyes; low-certainty evidence) as well as mean spherical equivalent of the refractive error 12 months after surgery (MD 0.09, 95% CI -0.01 to 0.19; 3 trials, 168 eyes [92 participants]; low-certainty evidence). Based on data from three trials (134 eyes, 66 participants), mechanical microkeratome was associated with lower risk of diffuse lamellar keratitis compared with femtosecond laser (RR 0.27, 95% CI 0.10 to 0.78; low-certainty evidence). Thus, diffuse lamellar keratitis was a more common adverse event with femtosecond laser than with mechanical microkeratome, decreasing from an assumed rate of 209 per 1000 people in the femtosecond laser group to 56 per 1000 people in the mechanical microkeratome group. Data from one trial (183 eyes, 183 participants) indicates that dry eye as an adverse event may be more common with mechanical microkeratome than with femtosecond laser, increasing from an assumed rate of 80 per 1000 people in the femtosecond laser group to 457 per 1000 people in the mechanical microkeratome group (RR 5.74, 95% CI 2.92 to 11.29; low-certainty evidence). There was no evidence of a difference between the two groups for corneal haze (RR 0.33, 95% CI 0.01 to 7.96; 1 trial, 43 eyes) and epithelial ingrowth (RR 1.04, 95% CI 0.11 to 9.42; 2 trials, 102 eyes [50 participants]). The certainty of evidence for both outcomes was very low.

AUTHORS' CONCLUSIONS

Regarding the visual acuity outcomes, there may be no difference between LASIK with mechanical microkeratome and LASIK with femtosecond laser. Dry eye and diffuse lamellar keratitis are likely adverse events with mechanical microkeratome and femtosecond laser, respectively. The evidence is uncertain regarding corneal haze and epithelial ingrowth as adverse events of each intervention. The limited number of outcomes reported in the included trials, some with potentially significant risk of bias, makes it difficult to draw a firm conclusion regarding the effectiveness and safety of the interventions investigated in this review.

Predictors of myopic photorefractive keratectomy retreatment

PURPOSE

To determine the factors associated with retreatment after photorefractive keratectomy (PRK) in myopic eyes.

SETTING

Care-Vision Laser Centers, Tel-Aviv, Israel.

DESIGN

Retrospective cohort study.

METHODS

A large database on myopic PRK with mitomycin-C (MMC) performed from 2005 to 2012 was studied. Patients were divided into 2 groups according to whether they had retreatment. Multiple preoperative and intraoperative parameters were analyzed for association with retreatment.

RESULTS

A total of 9699 eyes of 9699 consecutive patients were studied. The mean age was 25.9 years ± 7.3 (SD); 54.1% were men. The mean preoperative subjective spherical equivalent and astigmatism were -4.30 ± 2.18 diopters (D) (range -0.5 to -13.0 D) and 0.77 ± 0.83 D (range 0 to 6.0 D), respectively. Two hundred twenty-three eyes (2.30%) were retreated. The 2-year retreatment rate decreased from 42 (6.17%) for primary PRK treatments done in 2005 to 2 (0.10%) for primary PRK done in 2012 (R² = 0.79, P < .001). Multiple binary logistic regression analysis showed that transepithelial PRK, astigmatism equal to or higher than 3.5 D, and surgeon factor significantly increased the odds of retreatment. Additional parameters significant on univariate analysis alone included age older than 40 years, low preoperative sphere, maximum ablation depth less than 45 μm, preoperative corrected distance visual acuity better than 20/20, MMC application longer than 40 seconds, and optical ablation zone smaller than 7.0 mm.

CONCLUSION

The retreatment incidence of PRK has continued to decrease. High astigmatism and transepithelial PRK were associated with increased myopic PRK retreatment rates.

Evaluation of visual evoked potential binocular summation after corneal refractive surgery

PURPOSE

To explore whether visual evoked binocular summation is affected in eyes with refractive errors after refractive surgery.

METHODS

Twenty participants (6M, 14F) aged 20-35 years (mean 26.7 ± 4.4) were assessed through pattern-reversal visual evoked potential viewing with their every eye (first right eye and then left eye) and then with both eyes while wearing their best correction before undergoing surgery. Also, parameters of the P100 component of pattern-reversal visual evoked potential were evaluated after 3 months of refractive surgery in two different check sizes. Monocular and binocular amplitudes and latencies of P100 wave and binocular summation index were compared between before and after surgery.

RESULTS

Monocular visual evoked potentials elicited by two different high-contrast checkerboard-patterned stimuli were significantly reduced in P100 wave amplitude (P < 0.05) after refractive surgery. However, there was no difference between the pre- and post-refractive surgery in the mean value of monocular P100 latency (P > 0.05). Similar to monocular findings of P100 wave amplitude, on binocular viewing, the mean value of pattern-reversal visual evoked potential amplitude was significantly reduced (P < 0.05), and P100 wave latency was prolonged (P < 0.05) after refractive surgery in participants. Also, the mean postoperative binocular summation index value as compared to that in the preoperative was significantly lesser (P < 0.05) for the subject in this study.

CONCLUSIONS

Refractive surgery can degrade binocular visual performance throughout the change in visual evoked potential binocular summation. However, monocular function deteriorates less than binocular function after refractive surgery.

Comparison of mechanical debridement and trans-epithelial myopic photorefractive keratectomy: A contralateral eye study

Purpose

To compare clinical outcomes between mechanical debridement photorefractive keratectomy (m-PRK) and trans-epithelial photorefractive keratectomy (t-PRK) in myopic patients.

Methods

Eighty eyes of 40 myopic patients with age between 18 and 55 years were included in this study. In each patient, one eye was randomly assigned for t-PRK, using the Amaris laser's ORK-CAM software and the other eye for m-PRK, using a spatula. Stromal ablation was done by Schwind Amaris 750S. Uncorrected and best corrected visual acuity (BCVA), refractive outcomes, epithelial healing, pain, and discomfort were compared between the groups on day 1, 3, 7 and month 1, 3, and 6.

Results

Preoperative spherical equivalent (SE) were −3.97 ± 2.08 diopter (D) and −3.98 ± 2.06 D in m-PRK and t-PRK eyes, respectively (P = 0.981). Operation time was significantly shorter in the t-PRK group than m-PRK (P < 0.001). Postoperative pain was experienced significantly higher in the t-PRK group measured by 11-point numeric scale of pain questionnaire on the first postoperative day (P < 0.001). Photophobia, tearing, and vision fluctuation were also significantly higher in the t-PRK group postoperatively. However epithelial defect size and re-epithelialization time were lower in the t-PRK group (P = 0.012 and P < 0.001, respectively). Postoperative parameters including SE, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and contrast acuity did not show any significant difference between the two groups during all intervals.

Conclusions

Although epithelial defect size and epithelial healing time were lower in t-PRK, postoperative pain, photophobia, and vision fluctuation were significantly less in the m-PRK group in the first postoperative days. There was no statistically significant difference between the groups after one week, and both mechanical and trans-epithelial techniques were shown to be safe and effective.

Laser-assisted subepithelial keratectomy (LASEK) versus laser-assisted in-situ keratomileusis (LASIK) for correcting myopia

BACKGROUND

Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review.

OBJECTIVES

To assess the effects of LASEK versus LASIK for correcting myopia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We considered only randomized controlled trials (RCTs) for the purposes of this review. Eligible RCTs were those in which myopic participants were assigned randomly to receive either LASEK or LASIK in one or both eyes. We also included paired-eye studies in which investigators randomly selected which of the participant's eyes would receive LASEK or LASIK and assigned the other eye to the other procedure. Participants were men or women between the ages of 18 and 60 years with myopia up to 12 diopters (D) and/or myopic astigmatism of severity up to 3 D, who did not have a history of prior refractive surgery.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all reports and assessed the risk of bias in trials included in this review. We extracted data and summarized findings using risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes. In the absence of clinical and methodological heterogeneity across trials, we used a random-effects model to calculate summary effect estimates. We used a fixed-effect model when including fewer than three trials in a meta-analysis. When clinical, methodological, or statistical heterogeneity was observed across trials, we reported our findings in a narrative synthesis.

MAIN RESULTS

We identified four eligible trials with 538 eyes of 392 participants for the review, but only three trials (154 participants) provided outcome data for analysis. We found no ongoing trials. Two of four trials were from China, one trial was from Turkey, and the location of one trial was not reported. The risk of bias for most domains was unclear due to poor reporting of trial methods; no trial had a protocol or trial registry record. Three trials enrolled participants with mild to moderate myopia (less than -6.50 D); one trial included only participants with severe myopia (more than -6.00 D).The evidence showed uncertainty in whether there is a difference between LASEK and LASIK in uncorrected visual acuity (UCVA) at 12 months, the primary outcome in our review. The RR and 95% confidence interval (CI) at 12 months after surgery was 0.96 (95% CI 0.82 to 1.13) for UCVA of 20/20 or better and 0.90 (95% CI 0.67 to 1.21) for UCVA of 20/40 or better based on data from one trial with 57 eyes (very low-certainty evidence). People receiving LASEK were less likely to achieve a refractive error within 0.5 diopters of the target at 12 months follow-up (RR 0.69, 95% CI 0.48 to 0.99; 57 eyes; very low-certainty evidence). One trial reported mild corneal haze at six months in one eye in the LASEK group and none in the LASIK group (RR 2.11, 95% CI 0.57 to 7.82; 76 eyes; very low-certainty evidence). None of the included trials reported postoperative pain score or loss of visual acuity, spherical equivalent of the refractive error, or quality of life at 12 months.Refractive regression, an adverse event, was reported only in the LASEK group (8 of 37 eyes) compared with none of 39 eyes in the LASIK group in one trial (low-certainty evidence). Other adverse events, such as corneal flap striae and refractive over-correction, were reported only in the LASIK group (5 of 39 eyes) compared with none of 37 eyes in the LASEK group in one trial (low-certainty evidence).

AUTHORS' CONCLUSIONS

Overall, from the available RCTs, there is uncertainty in how LASEK compares with LASIK in achieving better refractive and visual results in mildly to moderately myopic participants. Large, well-designed RCTs would be required to estimate the magnitude of any difference in efficacy or adverse effects between LASEK and LASIK for treating myopia or myopic astigmatism.

[Evaluation of vision quality after laser vision correction in healthcare professionals]

PURPOSE

Healthcare professionals require good quality of vision. The main objective of this study is to evaluate the satisfaction and vision quality after laser vision correction in healthcare professionals.

METHODS

This is a monocentric retrospective study. An online 25-question survey was sent to ametropic physicians, surgeons and nurses who underwent corneal refractive surgery with laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between July 2012 and February 2016. Questionnaire responses were recorded anonymously by the internet survey site. These patients' pre- and postoperative data were analyzed.

RESULTS

In total, 2491 laser vision corrections were performed during this time frame. One hundred and fifty-eight patients were healthcare providers; 131 received the survey, and 111 responded. Ninety-nine were surgeons, 60 were medical physicians, and 32 were nurses. Ninety-one percent reported that they were satisfied with their postoperative vision quality, 63.9% even reported an improvement in their quality of vision compared with their corrected preoperative vision, 92.8% reported that they would have the procedure again, and 94.6% would recommend the procedure to a family member or a patient. Visual outcomes showed high levels of efficacy and predictability.

CONCLUSION

While healthcare professionals require good quality of vision, those who had undergone laser vision correction reported the same satisfaction as the general population and would recommend the procedure to their family, friends and patients.

Visual outcomes in adult amblyopic eyes with moderate myopia after corneal laser surgery versus copolymer phakic intraocular lens implant

PURPOSE

To assess visual acuity and refractive correction in moderately myopic adult eyes with suboptimal preoperative corrected distance visual acuity (CDVA) after laser in situ keratomileusis (LASIK) or insertion of a posterior chamber Implantable Collamer Lens phakic intraocular lens (pIOL).

SETTING

Clínica Baviera, Instituto Oftalmológico Europeo, Torrevieja Hospital, Madrid, Spain.

DESIGN

Retrospective study.

METHODS

The study sample included 1310 eyes that had LASIK and 94 that had insertion of a pIOL from July 2002 to September 2013. Suboptimal preoperative CDVA was defined as equal to logMAR 0.15 or below and moderate myopia as a spherical equivalent of -5.0 to -10.0 diopters (D).

RESULTS

The preoperative mean CDVA was 0.22 logMAR ± 0.09 (SD) in the LASIK group and 0.23 ± 0.09 logMAR in the pIOL group. Postoperative uncorrected distance visual acuity (UDVA) was 0.13 ± 0.12 logMAR in the laser group and 0.12 ± 0.09 logMAR in the pIOL group, with a postoperative CDVA of 0.11 ± 0.10 logMAR and 0.08 ± 0.07 logMAR, respectively.

CONCLUSIONS

Compared with preoperative values, amblyopic eyes with moderate myopia having LASIK or implantation of a pIOL demonstrated a statistically significant improvement in UDVA and CDVA (P < .001). The pIOL group performed significantly better than the LASIK group in terms of safety and efficiency.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Past and present of corneal refractive surgery: a retrospective study of long-term results after photorefractive keratectomy and a prospective study of refractive lenticule extraction

Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become possible. Two new procedures were developed, ReLEx flex (FLEX) and ReLEx smile (SMILE). Until this thesis, only a few long-term studies of PRK with a relatively limited number of patients had been published; therefore, this thesis intended to retrospectively evaluate long-term outcomes after PRK for all degrees of myopia for a large number of patients. Furthermore, a prospective contralateral eye study comparing FLEX and SMILE, when treating high to moderate degrees of myopia, had not been performed prior to this study. This was the second aim of this thesis. In the first study, results from 160 PRK patients (289 eyes) were presented. Preoperative spherical equivalent ranged from -1.25 to -20.25 D, with 78% having low myopia (<-6 D). Average follow-up time was 16 years (range 13-19 years), making this the longest published follow-up study on PRK patients. Outcomes from eyes with low myopia were generally superior to outcomes from eyes with high myopia, at final follow-up. Seventy-two percent were within ± 1.00 D of target refraction, as compared to 47% of eyes with high myopia. However, results from a subgroup of unilateral treated PRK patients indicated that refraction at final follow-up was affected by myopic progression. Fifty percent of eyes with low myopia had uncorrected 20/20 distance visual acuity or better, as compared to 22% of eyes with high myopia. Haze did not occur if attempted corrections were <-4 D, and only eyes with high myopia lost two lines or more of CDVA (corrected distance visual acuity). Eighty-one per cent were satisfied or very satisfied with their surgery.

CONCLUSION

The results support the continued use of the excimer laser for corneal surface ablation as a treatment option for correction of low degrees of myopia, and as the treatment of choice for subgroups of refractive patients (thin corneas, etc.). The results also highlight that treatment of higher degrees of myopia with standard PRK should only be done today under special circumstances, due to low refractive predictability, and high risk of corneal haze. Technological advances since then should be taken into account when comparing these results with contemporary techniques. In the second study, 35 patients were randomized to receive FLEX in one eye and SMILE in the other. Preoperative spherical equivalent refraction ranged from -6 to -10 D with low degrees of astigmatism. A total of 34 patients completed the 6 month follow-up period. Refractive and visual outcomes were very similar for the two methods, as well as tear film measurements and changes in corneal biomechanics. Ninety-seven percent were within ± 1.00 D of target refraction, no eyes lost two lines or more of CDVA, and contrast sensitivity was unaffected after both procedures. The changes in higher-order aberrations were also very similar. There were also no differences in tear film parameters 6 months after surgery, although less postoperative foreign body sensation was reported within the first week after surgery in SMILE eyes. Corneal sublayer pachymetry measurements demonstrated equally increased epithelial thickness 6 months after surgery. Contrary to expectations, it was not possible to measure the theoretical biomechanical advantages of a small corneal incision in SMILE as compared to a corneal flap in FLEX. The main differences between FLEX and SMILE were found when the corneal nerves and intraoperative complications were evaluated. Thus, corneal sensitivity was better preserved and corneal nerve morphology was less affected after SMILE, but intraoperative complications occurred more frequently, although without visual sequela. Finally, 97% were satisfied or very satisfied with both their surgeries.

CONCLUSION

The results support the continued use of both FLEX and SMILE for treatment of up to high degrees of myopia. Overall, refractive and visual results for both procedures were good and similar, but from a biological point of view, the less invasive SMILE technique is more attractive, as demonstrated in this study, despite being slightly more surgically demanding than FLEX.

Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx(®) flex and comparison with a retrospective study of FS-laser in situ keratomileusis

PURPOSE

To present our initial clinical experience with ReLEx(®) flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher-order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS-LASIK).

METHODS

Prospective study of ReLEx compared with a retrospective study of FS-LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS-LASIK patients were retrospectively identified. Visual acuity, spherical equivalent (SE) and corneal tomography were measured before and 3 months after surgery.

RESULTS

Preoperative SE averaged -7.50 ± 1.16 D (ReLEx) and -7.32 ± 1.09 D (FS-LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction, 41% of ReLEx and 61% of FS-LASIK eyes had an uncorrected distance visual acuity of logMAR ≤ 0.10 at day 1 after surgery, increasing to, respectively, 88% and 69% at 3 months. Mean SE was -0.06 ± 0.35 D 3 months after ReLEx and -0.53 ± 0.60 D after FS-LASIK. The proportion of eyes within ±1.00 D after 3 months was 100% (ReLEx) and 85% (FS-LASIK). For a 6.0-mm pupil, corneal spherical aberrations increased significantly less in ReLEx than FS-LASIK eyes.

CONCLUSIONS

ReLEx is an all-in-one femtosecond laser refractive procedure, and in this study, results were comparable to FS-LASIK. Refractive predictability and corneal aberrations at 3 months seemed better than or equal to FS-LASIK, whereas visual recovery after ReLEx was slower.