Outcomes of LASIK vs PRK enhancement in eyes with prior cataract surgery

PURPOSE

To compare postenhancement visual acuity between patients who underwent postcataract laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK).

SETTING

A private, tertiary referral practice in Sioux Falls, South Dakota.

DESIGN

3-year, retrospective chart review.

METHODS

Patients who underwent postcataract extraction excimer laser enhancement surgery targeted for emmetropia (±0.50 diopter). Postenhancement uncorrected distance visual acuity (UDVA) and manifest refraction spherical equivalent (MRSE) was recorded for all available follow-ups and compared for both groups.

RESULTS

822 postcataract enhanced eyes (491 LASIK; 331 PRK). For patients with at least 6-month follow-up, mean UDVA was 0.05 ± 0.13 logMAR in LASIK-enhanced patients and 0.15 ± 0.20 in PRK-enhanced patients ( P < .001). Mean absolute value MRSE was 0.22 ± 0.36 and 0.48 ± 0.62 for LASIK-enhanced and PRK-enhanced patients at or beyond 6 months, respectively ( P < .001). 330 (67%) LASIK-enhanced patients achieved 20/20 or better postenhancement UDVA, compared with 142 (43%) PRK-enhanced patients ( P < .001). Controlling for pre-enhancement UDVA, LASIK-enhanced patients showed significantly better postenhancement UDVA than PRK-enhanced patients, except in those with pre-enhancement vision of 20/20 or better, or those worse than 20/50. LASIK-enhanced virgin corneas had mean postenhancement of 0.05 ± 0.14 UDVA compared with 0.13 ± 0.19 UDVA in PRK-enhanced virgin cornea patients ( P < .001).

CONCLUSIONS

LASIK provides better and more predictable outcomes in UDVA than PRK in postcataract enhancement patients, even when controlling for pre-enhancement visual acuity and prior ocular procedures.

Twelve-Month Outcomes of the Wavefront-Optimized Photorefractive Keratectomy for High Myopic Correction Compared with Low-to-Moderate Myopia

Purpose

To evaluate the 12-months outcomes of photorefractive keratectomy (PRK) in patients with high myopia (≥ 6.0 diopters, D) compared with low-to-moderate myopia (< 6.0 D).

Patients and Methods

Records of 46 patients (69 eyes) who underwent PRK for myopic and astigmatic correction between October 2015 and December 2018 were reviewed. High myopic eyes (29 eyes) were compared with low-to-moderate myopic eyes (40 eyes). All surgeries were adjunct with 0.02% mitomycin C intraoperatively. Measured outcomes included postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, corneal haze rate, and any complications.

Results

At 12 months post-PRK, 26 eyes (89.7%) in the high myopia and 39 eyes (97.5%) in the low-to-moderate myopia group had UDVA ≥ 20/20, (p=0.30). Average postoperative logMAR UDVA at 12 months was −0.04 (20/18) and −0.11 (20/15) for the high myopia and low-to-moderate myopia groups, respectively. No eyes in either group had residual refractive errors >1 D. No eyes in both groups developed significant corneal haze at month 12. No eyes had a loss of greater than two Snellen lines of CDVA at 12 months post-surgery. The efficacy and safety indices at 12 months post-surgery were not significantly different between groups (1.06±0.26 vs.1.14±0.27, p =0.25 and 1.14±0.27 vs 1.17±0.26, p=0.60 for low-to-moderate myopia vs high myopia groups, respectively).

Conclusion

PRK with high myopic correction provides excellent refractive outcomes and is safe, compared to those of low-to-moderate myopic correction.

Implantable collamer lens versus small incision lenticule extraction for high myopia correction: A systematic review and meta-analysis

Purpose

To compare the efficacy, safety, predictability and visual quality between implantable collamer lens (ICL) implantation and small incision lenticule extraction (SMILE) for high myopia correction in adults.

Methods

A systematic review and meta-analysis was conducted. A comprehensive literature search was done based on databases including PubMed, Science Direct, Embase, and the Cochrane Central Register of Controlled Trials. The efficacy index, safety index, changes in Snellen lines of corrected distance visual acuity (CDVA), predictability (difference between post-operative and attempted spherical equivalent error, SER), incidence of halos, and change in higher-order aberrations (HOAs) were compared. Mean difference (MD) and 95% confidence interval (CI) was used to estimate continuous outcomes, risk ratio (RR) and 95%CI was used to estimate categorical outcomes.

Results

Five observational studies involving 555 eyes were included in this review. Studies’ sample sizes (eyes) ranged from 76 to 197. Subjects’ refraction ranged from -6 diopter (D) to -12D. Study duration of most researches were 6 months or 12 months. Compared to SMILE, ICL implantation showed better efficacy index (MD=0.09, 95%CI:0.01 to 0.16) and better safety index (MD=0.08, 95%CI: 0.00 to 0.16). Compared with SMILE, more ICL-treated eyes gained one or more Snellen lines of CDVA (RR=1.54, 95%CI:1.28 to 1.86), more gained two or more lines (RR=2.09, 95%CI:1.40 to 3.13), less lost one or more lines (RR=0.17, 95%CI:0.05 to 0.63). There was no difference in predictability between two treatments, RRs of predictability of within ±0.5D and ±1D were 1.13 (95%CI: 0.94 to 1.36) and 1.00 (95%CI: 0.98 to 1.02). Compared with SMILE, ICL implantation came with a higher risk of halos [RR=1.79, 95%CI: 1.48 to 2.16] and less increase in total HOAs (MD=-0.23, 95%CI: -0.42 to -0.03).

Conclusion

Compared with SMILE, ICL implantation showed a higher risk of halos, but equal performance on SER control, and better performance on efficacy index, safety index, CDVA improvement and HOAs control. Overall, ICL implantation might be a better choice for high myopia correction in adults.

Surface ablation outcomes in high myopia with different epithelium removal techniques

PURPOSE

To study the outcomes of alcohol-assisted photorefractive keratectomy (PRK) when compared with transepithelial PRK (TransPRK) using 2 software programs, with or without SmartPulse Technology (SmartSurfACE), in high myopia.

SETTING

Vissum Miranza, University Miguel Hernandez, Alicante, Spain.

DESIGN

Retrospective, consecutive, case series.

METHODS

High myopic eyes undergoing surface ablation were included. The main inclusion criteria were preoperative spherical equivalent (SE) above -5.50 diopters (D) and no other ocular surgeries. Mitomycin-C was used in all the surgeries. The outcomes were analyzed using the 6-month follow-up visit data.

RESULTS

135 eyes were included. Alcohol-assisted PRK was performed in 65 eyes, transepithelial PRK (TransPRK1) in 32 eyes, and TransPRK2 in 38 eyes. The mean all groups preoperative sphere, cylinder, and SE were -6.00 ± 0.87 D, -1.13 ± 1.03 D, and -6.57 ± 0.69 D, respectively. The mean efficacy index in the alcohol-assisted PRK group was 0.91 ± 0.18 compared with 0.98 ± 0.1 and 0.98 ± 0.12 in the TransPRK1 and TransPRK2, respectively (P = .027). The mean safety index in alcohol-assisted PRK was 0.99 ± 0.05, whereas it was 1 ± 0.06 in the TransPRK1 and 0.99 ± 0.08 in the TransPRK2 (P = .780). A final SE of ± 0.50 D was achieved in 96.9% of eyes in the TransPRK1 group and in 100% eyes in the TransPRK2 group compared with 73.8% in the alcohol-assisted PRK group (P < .001).

CONCLUSIONS

Surface ablation with the Amaris 500 excimer laser with flying spot pattern and mitomycin C use showed adequate refractive outcomes in high myopia correction in the 3 groups. TransPRK with or without SmartPulse Technology achieved statistically significant better outcomes than alcohol-assisted PRK in refractive predictability and efficacy.

[Regression and ablation profiles in corneal refractive surgery]

Regression after corneal refractive surgery is a complex phenomenon which seems inevitable. The choice of surgical technique has very little influence on regression for low myopia or myopic astigmatism. However, LASIK and SMILE are the two techniques of choice in the correction of high myopia. LASIK is also better for the correction of hyperopia, hyperopic astigmatism and mixed astigmatism. Intraoperatively, the choice of a wide optical zone and adherence to a thick residual stromal bed provide stability. Regression may also be reduced by modulating anti-inflammatory therapy, treating dry eye, and using mitomycin C in PKR. In all cases, obtaining keratometry during patient follow-up helps to identify the cause of the regression. The objective of this review is to synthesize recent data from the literature on regression in refractive surgery as a function of the ablation profiles used.

Keratorefractive Surgery Outcomes in Keratoconus Suspect Patients

Purpose. To examine the outcomes of keratorefractive surgeries in keratoconus suspect patients. Methods. This study included 192 keratoconus suspects (351 eyes), treated with photorefractive keratectomy (PRK) (211 eyes), Lasik (96 eyes), and Femto-Lasik (44 eyes) surgeries in an eye clinic. The best spectacle-corrected visual acuity (BSCVA) and subjective refraction were evaluated preoperatively and postoperatively (three months and five years after the procedure). The Orbscan II topography system was also used preoperatively and five years after the procedure. Results. The patients’ mean age was 31.6 ± 5.49 years (range: 21–47 years) in the last follow-up. There was no significant difference between the preoperative and postoperative mean values of BSCVA in any of the surgical methods ( $P$  = 0.49). The mean spherical equivalent, cylindrical power, corneal curvature, the thinnest corneal thickness, and the central corneal thickness decreased significantly in the last follow-up ( $P$  < 0.001). Four patients (3.50%) in the PRK group and one patient (1.85%) in the Lasik group needed glasses in the last follow-up. Eleven cases of corneal ectasia were detected in the last follow-up (six eyes of four patients [2.84%] and five eyes of four patients [5.20%] in the PRK and Lasik groups, respectively). Conclusion. In the present study, the high risk of postoperative ectasia was detected in keratoconus suspects following PRK and Lasik surgeries. According to the results, it can be concluded that Femto-Lasik surgery provides better outcomes than Lasik and PRK. Overall, the surgical criteria are suggested to be evaluated case by case, and the patients must be followed up over time to assess the corneal topography and refraction stability.

Refractive, visual, and subjective quality of vision outcomes for very high myopia LASIK from - 10.00 to - 13.50 diopters

Background

To evaluate laser-assisted in situ keratomileusis (LASIK) outcomes, subjective quality of vision (QoV) and patient satisfaction in eyes with very high myopia (VHM) above − 10.00 diopters (D).

Methods

Consecutive myopic and myopic-astigmatism eyes with spherical equivalent (SEQ) ranging between − 10.00 to − 13.50 D underwent LASIK with the WaveLight® Allegretto Wave® Eye-Q 400 Hz excimer laser. Treatment accuracy, efficacy, safety, stability, cylinder vectors, and higher-order aberrations were evaluated, together with subjective QoV and night vision disturbances (NVDs).

Results

114 eyes had a preoperative SEQ of − 11.02 ± 0.81 D, with a median follow-up of 24 months. A total of 72, 84, and 94% of eyes were within ± 0.50, ± 0.75 and ± 1.00 D of intended SEQ (R² = 0.71). The efficacy index was 0.93 ± 0.20, with 51 and 81% of eyes achieving 20/20 and 20/25. The astigmatism correction index was 0.95 ± 0.33. The safety index was 1.05 ± 0.12. The average myopic regression was − 0.51 ± 0.38 D. Preoperative QoV scores improved significantly postoperatively (7.5 ± 0.8 vs. 9.1 ± 0.7; P <  0.001), with less NVDs (P <  0.001). Total, spherical and coma root mean square (RMS) postoperative ocular higher-order aberrations were 1.07 ± 0.34, 0.67 ± 0.25, and 0.70 ± 0.40 μm.

Conclusions

Very high myopia LASIK between − 10.00 to − 13.50 D is safe and results in good visual outcomes, with high patient satisfaction and a significant improvement in patient-reported QoV after surgery. Appropriately selected patients within this very high myopia group can be included as LASIK candidates.

Long-Term Outcomes of Refractive Surgery Performed During the Military

INTRODUCTION

To evaluate the long-term refractive results of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) performed by the military in a veteran population.

MATERIALS AND METHODS

Three Department of Veterans Affairs (VA) hospital sites (Puget Sound, Buffalo, and Washington D.C.) obtained IRB approval for this multi-center study. Comprehensive ophthalmologic assessment including refraction and keratometry were obtained at the time of the long-term VA examination and compared to the patients' postoperative military records.

RESULTS

Eighty patients (160 eyes) enrolled in this study. At the time of treatment, patients were 21-52 years of age. Long-term post-operative data was available from 4 to 17 years post-operatively. Fifteen percent of the treatment types were LASIK and 85% PRK. At the time of their military post-operative exam (range 3-14 months, mean 4 months), 82% of patients had uncorrected visual acuity (UCVA) of 20/20 or better, and their average manifest refraction was -0.08 D (SD ± 0.48 D). At the time of the long-term ophthalmological exam at the VA medical centers (range 4-11 years, mean of 8.2 years), 49% of patients had an UCVA of 20/20 or better and an average manifest refraction was -0.64 D (SD ± 0.69 D).

CONCLUSION

This is the first long-term study evaluating refractive surgery outcomes up to 17 years in a military population. Our study demonstrates safety after refractive surgery in the military with less than 0.1D increase in myopia per year and strong keratometric stability. Other changes in the eye may be the likely cause for this observed mild refractive shift.

Factors Affecting Myopic Regression after Laser in Situ Keratomileusis and Laser-Assisted Subepithelial Keratectomy for High Myopia

To evaluate the factors affecting the amount of myopic regression after laser refractive surgery for high myopia, we retrospectively reviewed medical records of 1591 eyes with high myopia treated by laser in situ keratomileusis or laser-assisted subepithelial keratectomy at Shandong Eye Hospital between January 2008 and December 2012. Thirty-five eyes suffering a postoperative myopic shift of manifest spherical equivalent (MSE) of 0.25 diopter (D) or greater were included in this study. The mean refractive error was -9.34 ± 1.89 D before surgery, and the mean regression was -1.22 ± 0.70 D. Correlation analysis and multiple regression analysis were performed to assess the factors that were associated with the refractive regression. The age displayed a negative correlation with the diopter of regression (R = -0.404, P = .016), while the optical zone diameter had a positive correlation with it (R = 0.406, P = .016). Explanatory variables relevant to the diopter of regression were age (partial regression coefficient B = -0.045, P = .016) and optical zone diameter (partial regression coefficient B = 0.979, P = .014). Advanced-age patients with small optical zones were more predisposed to a larger amplitude of regression after laser refractive surgery for high myopia.

Comparison of laser in situ ketatomileusis and photorefractive keratectomy for myopia using a mixed-effects model

Purpose

To compare the results of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopia using a mixed-effects model.

Methods

This comparative retrospective study was conducted in 1,127 eyes of 579 patients after LASIK and 270 eyes of 144 patients after PRK who had two or more postoperative follow-ups after 3 months. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), percentage of eyes within ± 0.5 diopters (D) and ± 1.0 D of targeted refraction, and central corneal thickness were compared between PRK and LASIK groups using a mixed-effects model.

Results

Compared with the LASIK group, UCVA in the PRK group was significantly worse in the initial year but was significantly better after 4 years. The average BSCVA was not significantly different between the LASIK and PRK groups after 4 years. The average gain of BSCVA in the PRK group was significantly larger than that of the LASIK group after 2 years. MRSE in the LASIK and PRK groups showed a gradual myopic shift until 6 years after surgery. After 6 years, MRSE in the PRK group remained stable whereas MRSE in the LASIK group continued a myopic shift. The percentages of eyes within ± 0.5 D or ± 1.0 D in the LASIK group were significantly higher than those in the PRK group at 3 months but were significantly lower than those in the PRK group at 10 years.

Conclusions

PRK for myopia shows better efficacy than LASIK for myopia after 4 years.

Femtosecond-Assisted LASIK Versus PRK: Comparison of 6-Month Visual Acuity and Quality Outcome for High Myopia

OBJECTIVE

To compare the results of femtosecond-assisted laser in situ keratomileusis (femto-LASIK) and photorefractive keratectomy with mitomycin C (PRK-MMC) for the correction of myopia more than 7.0 diopters (D).

METHODS

In this comparative nonrandomized trial, 60 eyes (30 eyes in each group) were enrolled. Patients were tested for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, ocular and corneal aberrations, and contrast sensitivity (CS) before surgery and at 3 and 6 months postoperatively.

RESULTS

Mean preoperative myopia was -8.65±1.51 and -8.04±1.70 D in the femto-LASIK and PRK-MMC groups, respectively (P=0.149). Intergroup differences in baseline indices were not statistically significant. At 6 months after surgery, UDVA showed an improving trend, but it was better in the femto-LASIK group (P=0.026). CDVA in the two groups remained similarly unchanged (P=0.170). For the femto-LASIK and PRK-MMC groups, the safety indices were 1.01±0.05 and 1.01±0.14 (P=0.949), respectively, and the efficacy indices were 0.99±0.07 and 0.93±0.22 (P=0.192), respectively. Comparing CS, only CS18 showed a significantly greater decrease in the femto-LASIK group compared with the PRK-MMC group (P=0.016). Intergroup differences were not statistically significant in other spatial frequencies. Changes in the ocular and corneal higher order aberrations were not statistically different between the two groups except ocular coma, which increased in the femto-LASIK group (P=0.041).

CONCLUSION

Femto-LASIK improves UDVA better than PRK-MMC in high myopia. However, because of increased coma, the quality of vision is reduced. In other words, visual acuity outcome is better with femto-LASIK and visual quality outcome is better with PRK-MMC.

Long-Term Clinical Outcomes of Myopic Patients Having Thin Residual Corneal Thickness after Excimer Laser Surface Ablation

PURPOSE

To investigate and compare the long-term safety, efficacy, and accuracy of PRK (photorefractive keratectomy) and LASEK (laser epithelial keratomileusis) in myopic corneas having residual corneal thickness less than 400 micron meters (µm).

METHODS

The medical reports of the patients who had undergone excimer laser surface ablation between 2007-2011 and had a residual corneal thickness less than 400 µm were retrospectively reviewed.

RESULTS

Forty-two eyes of 42 patients with a mean age of 28.79±7.76 years were enrolled into the study. Twenty-two PRK and 20 LASEK procedures were performed. The mean follow-up time was 45.00±11.80 months. At the end of follow-up, no ectasia was detected. Nineteen percent of eyes had trace haze. No eyes lost any lines in corrected distance visual acuity. Eighty-one percent of the patients had an uncorrected distance visual acuity better than 20/40. The regression rate was 16.7%. Sixty-two percent of eyes were within ±1.00 D. The safety and efficacy indexes were 1.19±0.42 and 1.00±0.40, respectively. There was not any difference between LASEK and PRK regarding achieved spherical equivalent refraction, haze ratio, visual acuity, safety, efficacy, and regression.

CONCLUSIONS

Both PRK and LASEK are safe and effective in myopic corneas having thin residual thickness.

Laser-assisted subepithelial keratectomy (LASEK) versus photorefractive keratectomy (PRK) for correction of myopia

BACKGROUND

Myopia (near-sightedness or short-sightedness) is a condition in which the refractive power of the eye is greater than required. The most frequent complaint of people with myopia is blurred distance vision, which can be eliminated by conventional optical aids such as spectacles or contact lenses, or by refractive surgery procedures such as photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). PRK uses laser to remove the corneal stroma. Similar to PRK, LASEK first creates an epithelial flap and then replaces it after ablating the corneal stroma. The relative benefits and harms of LASEK and PRK, as shown in different trials, warrant a systematic review.

OBJECTIVES

The objective of this review is to compare LASEK versus PRK for correction of myopia by evaluating their efficacy and safety in terms of postoperative uncorrected visual acuity, residual refractive error, and associated complications.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision group Trials Register) (2015 Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to December 2015), EMBASE (January 1980 to December 2015), Latin American and Caribbean Health Sciences (LILACS) (January 1982 to December 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), 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 15 December 2015. We used the Science Citation Index and searched the reference lists of the included trials to identify relevant trials for this review.

SELECTION CRITERIA

We included in this review randomized controlled trials (RCTs) comparing LASEK versus PRK for correction of myopia. Trial participants were 18 years of age or older and had no co-existing ocular or systemic diseases that might affect refractive status or wound healing.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all reports and assessed the risk of bias of trials included in this review. We extracted data and summarized findings using risk ratios and mean differences. We used a random-effects model when we identified at least three trials, and we used a fixed-effect model when we found fewer than three trials.

MAIN RESULTS

We included 11 RCTs with a total of 428 participants 18 years of age or older with low to moderate myopia. These trials were conducted in the Czech Republic, Brazil, Italy, Iran, China, Korea, Mexico, Turkey, USA, and UK. Investigators of 10 out of 11 trials randomly assigned one eye of each participant to be treated with LASEK and the other with PRK, but did not perform paired-eye (matched) analysis. Because of differences in outcome measures and follow-up times among the included trials, few trials contributed data for many of the outcomes we analyzed for this review. Overall, we judged RCTs to be at unclear risk of bias due to poor reporting; however, because of imprecision, inconsistency, and potential reporting bias, we graded the quality of the evidence from very low to moderate for outcomes assessed in this review.The proportion of eyes with uncorrected visual acuity of 20/20 or better at 12-month follow-up was comparable in LASEK and PRK groups (risk ratio (RR) 0.98, 95% confidence interval (95% CI) 0.92 to 1.05). Although the 95% CI suggests little to no difference in effect between groups, we judged the quality of the evidence to be low because only one trial reported this outcome (102 eyes). At 12 months post treatment, data from two trials suggest no difference or a possibly small effect in favor of PRK over LASEK for the proportion of eyes achieving ± 0.50 D of target refraction (RR 0.93, 95% CI 00.84 to 1.03; 152 eyes; low-quality evidence). At 12 months post treatment, one trial reported that one of 51 eyes in the LASEK group lost one line or more best-spectacle corrected visual acuity compared with none of 51 eyes in the PRK group (RR 3.00, 95% CI 0.13 to 71.96; very low-quality evidence).Three trials reported adverse outcomes at 12 months of follow-up or longer. At 12 months post treatment, three trials reported corneal haze score; however, data were insufficient and were inconsistent among the trials, precluding meta-analysis. One trial reported little or no difference in corneal haze scores between groups; another trial reported that corneal haze scores were lower in the LASEK group than in the PRK group; and one trial did not report analyzable data to estimate a treatment effect. At 24 months post treatment, one trial reported a lower, but clinically unimportant, difference in corneal haze score for LASEK compared with PRK (MD -0.22, 95% CI -0.30 to -0.14; 184 eyes; low-quality evidence).

AUTHORS' CONCLUSIONS

Uncertainty surrounds differences in efficacy, accuracy, safety, and adverse effects between LASEK and PRK for eyes with low to moderate myopia. Future trials comparing LASEK versus PRK should follow reporting standards and follow correct analysis. Trial investigators should expand enrollment criteria to include participants with high myopia and should evaluate visual acuity, refraction, epithelial healing time, pain scores, and adverse events.

Fifteen years follow-up of photorefractive keratectomy up to 10 D of myopia: outcomes and analysis of the refractive regression

PURPOSE

To evaluate outcomes of photorefractive keratectomy up to -10.00 D of myopia and -4.50 of astigmatism and to develop a predictive model for the refractive changes in the long term.

SETTING

Vissum Corporation and Miguel Hernandez University (Alicante, Spain).

DESIGN

Retrospective-prospective observational series of cases.

METHODS

This study included 33 eyes of 33 patients aged 46.79±7.04 years (range 40-57) operated with the VISX 20/20 excimer laser with optical zones of 6 mm. No mitomycin C was used in any of these cases. The minimum follow-up was 15 years. The main outcome measures were: uncorrected and corrected distance visual acuity, manifest refraction and corneal topography. Linear regression models were developed from the observed refractive changes over time.

RESULTS

Safety and efficacy indexes at 15 years were 1.18 and 0.83, respectively. No statistically significant differences were detected for any keratometric variable during the follow-up (p≥0.103). 15 years after the surgery 54.55% of the eyes were within ±1.00 D of spherical equivalent and 84.85% within ±2.00 D. The uncorrected distance visual acuity at 15 years was 20/25 or better in 60.6% of the eyes and 20/40 or better in 72.73% of the eyes. The correlation between the attempted and the achieved refractions was r=0.948 (p<0.001) at 1 year, and r=0.821 (p<0.001) at 15 years. No corneal ectasia was detected in any case during the follow-up.

CONCLUSIONS

Photorefractive keratectomy is a safe refractive procedure in the long term within the range of myopia currently considered suitable for its use, although its efficacy decreases with time, especially, in high myopia. The model developed predicts a myopic regression of 2.00 D at 15 years for an ablation depth of 130 µm.

Matched optical quality comparison of 3-year results of PRK-MMC and phakic IOL implantation in the correction of high myopia

AIMS

To compare 3-year results of PRK-MMC and phakic intraocular lens (PIOL) implantation in patients with >8.0 diopters (D) of myopia.

METHODS

This study was conducted as a non-randomized clinical trial on 23 eyes treated with PIOL (Artiflex; group A) and 23 eyes treated with PRK-MMC (group B). This report compares 3-year treatment results in these two groups.

RESULTS

At 3 years after surgery, uncorrected visual acuity was 0.02±0.06 LogMAR in group A and 0.04±0.07 LogMAR in group B (P=0.639). Mean best corrected visual acuity in group A (0.004±0.02) was better than group B (0.03±0.07 LogMAR) (P=0.035). Mean manifest refraction spherical equivalent was -0.16±0.21 and -0.09±0.20D (P=0.190), respectively. Mesopic contrast sensitivity (CS) in the spatial frequency of three cycle/degree (CS3) significantly decreased in both groups, but the reduction was significantly higher in group B (P=0.024). CS6 decreased significantly only in group B (P=0.019). Changes in CS12 and CS18 showed no significant inter-group difference. In group A, the increase in C6 trefoil (0.16±0.18 μm, P=0.003) and reduction in spherical aberration (SA; 0.16±0.08 μm, P<0.001) were statistically significant. In group B, the reduction in vertical coma (P=0.052), and increases in horizontal coma (P=0.044), coma (P<0.001), SA (P<0.001), and total higher order aberrations (P<0.001) were significant after surgery.

CONCLUSION

Based on 3-year results, PIOL implantation is a better choice than PRK-MMC for treating patients with >8.0D myopia. However, for patients with an inadequate aqueous depth, PRK-MMC can be an acceptable treatment option with a potential for decreased quality of vision.

Laser in situ keratomileusis for -6.00 to -18.00 diopters of myopia and up to -5.00 diopters of astigmatism: 15-year follow-up

PURPOSE

To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for high myopia with or without astigmatism.

SETTING

Vissum Instituto Oftalmologico de Alicante and Miguel Hernandez University, Alicante, Spain.

DESIGN

Retrospective-prospective case series.

METHODS

Laser in situ keratomileusis was performed using the Visx 20/20 excimer laser. The minimum follow-up was 15 years. The main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, and corneal topography.

RESULTS

This study included 40 patients (40 eyes) with a mean age of 51.08 years ± 6.67 (SD) (range 41 to 60 years) with high myopia (-6.00 to -18.00 diopters [D]). At 15 years, the safety index was 1.23 and the efficacy index, 0.95. During the follow-up, a significant increase in the dioptric power of all keratometric variables was detected (P≤.028, Friedman test), the most notable increase occurring between 3 months and 1 year (P≤.005). At 15 years, 46.15% of the eyes were within ±1.00 D of the attempted spherical equivalent and 64.10% were within ±2.00 D. The UDVA at 15 years was 20/25 or better in 43.59% of eyes and 20/40 or better in 64.10% of eyes. The postoperative CDVA was significantly better than preoperatively (P<.001). The postoperative complications were minor except in 1 eye in which ectasia occurred.

CONCLUSIONS

Laser in situ keratomileusis for high myopia was safe over the long term. However, significant myopic regression with time was detected. Low preoperative pachymetry and low residual stromal bed were predictors of keratometric regression.

FINANCIAL DISCLOSURE

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

Comparison of the visual outcomes between PRK-MMC and phakic IOL implantation in high myopic patients

PURPOSE

To compare the visual outcomes between PRK-MMC and phakic IOL in patients with more than 8 diopter (D) of myopia.

METHODS

This comparative study was performed on 23 eyes under treatment with Artiflex (group A) and 23 eyes under treatment with PRK-MMC (group B). Artiflex phakic IOL (Ophtec BV) was used in group A, and the VISX STAR S4 Excimer Laser (Abbott) was used for PRK-MMC in group B.

RESULTS

The safety index was 1.11 ± 0.23 and 1.05 ± 0.25 (P = 0.100) and the efficacy index was 1.02 ± 0.11 and 0.98 ± 0.10 (P = 0.266) in group A and B, respectively. At 1 year after surgery, the manifest refraction spherical equivalent was -0.17 ± 1.18 and -0.25 ± 0.18 D in group A and B, respectively (P = 0.471). Mesopic CS showed no significant difference between the two groups in any spatial frequency. Total coma was 0.24 ± 0.17 and 0.67 ± 0.40 μm (P < 0.001), spherical aberration was -0.11 ± 0.11 and 0.41 ± 0.18 μm (P < 0.001), and RMS HOAT was 0.50 ± 0.20 and 0.96 ± 0.45 μm (P<0.001) in group A and B, respectively.

CONCLUSION

Phakic IOL implantation was better than PRK-MMC in the correction of high myopia in terms of visual quality, but the two methods had no difference with regard to visual acuity. Therefore, PRK-MMC can be used when the anterior chamber depth is a limiting factor in the implantation of phakic IOLs.

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.

Laser in situ keratomileusis using optimized aspheric profiles and cyclotorsion control to treat compound myopic astigmatism with high cylinder

PURPOSE

To evaluate the visual outcomes after laser in situ keratomileusis (LASIK) surgery to correct primary compound myopic astigmatism with high cylinder performed using a fast-repetition-rate excimer laser platform with optimized aspheric profiles and cyclotorsion control.

SETTING

Vissum Corporation and Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain.

DESIGN

Retrospective consecutive observational nonrandomized noncomparative case series.

METHODS

Eyes with primary compound myopic astigmatism and a cylinder power over 3.00 diopters (D) had uneventful LASIK with femtosecond flap creation and fast-repetition-rate excimer laser ablation with aspheric profiles and cyclotorsion control. Visual, refractive, and aberrometric outcomes were evaluated at the 6-month follow-up. The astigmatic correction was evaluated using the Alpins method and Assort software.

RESULTS

The study enrolled 37 eyes (29 patients; age range 19 to 55 years). The significant reduction in refractive sphere and cylinder 3 months and 6 months postoperatively (P<.01) was associated with improved uncorrected distance visual acuity (P<.01). Eighty-seven percent of eyes had a spherical equivalent within ±0.50 D; 7.5% of eyes were retreated. There was no significant induction of higher-order aberrations (HOAs). The targeted and surgically induced astigmatism magnitudes were 3.23 D and 2.96 D, respectively, and the correction index was 0.91. The safety and efficacy indices were 1.05 and 0.95, respectively.

CONCLUSIONS

Laser in situ keratomileusis for primary compound myopic astigmatism with high cylinder (>3.00 D) performed using a fast-repetition-rate excimer laser with optimized aspheric profiles and cyclotorsion control was safe, effective, and predictable and did not cause significant induction of HOAs.