Ten-year follow-up of laser in situ keratomileusis for myopia of up to -10 diopters

Outcomes and Complications in Patients With Hypermobile Ehlers-Danlos Syndrome Who Have Undergone Laser In Situ Keratomileusis Surgery

PURPOSE

The purpose of this study was to determine the safety and outcomes of myopic laser in situ keratomileusis (LASIK) in patients who were secondarily diagnosed with hypermobile Ehlers-Danlos syndrome (EDS).

METHODS

We conducted a case series study on patients with hypermobile EDS who underwent myopic LASIK surgery. Visual acuity, manifest refraction, a full dilated eye examination, biometry measurements, and Scheimpflug imaging were performed in the Wilmer outpatient clinic.

RESULTS

There were 24 eyes of 12 patients included in this study. All participants were White women with a mean age of 46.58 years (SD 8.91 years). Participants were seen at an average of 13.83 years (SD 4.3 years, range 6-21 years) after undergoing LASIK. None of the patients in the series had a diagnosis of hypermobile EDS before LASIK surgery. Overall, 92% of patients were happy they got LASIK. The uncorrected distance visual acuity was 20/20 or better in 68% of eyes, and the best-corrected visual acuity was 20/20 or better in 92% of eyes. Manifest refraction was within 1 diopter of plano in 79% of patients. Dry eye symptoms were present in 83% of patients, and 46% of eyes had either punctate epithelial erosions or decreased tear break-up time. One of the 12 patients developed corneal ectasia in both eyes.

CONCLUSIONS

Patients with hypermobile EDS are generally satisfied with myopic LASIK correction, with good visual acuity outcomes and low rates of myopic regression. However, the risk of corneal ectasia may prevent laser vision correction from being a viable treatment option in these patients. Further studies are needed to make a definitive recommendation.

Clinical Outcomes Comparison of Combined Small Incision Lenticule Extraction with Collagen Cross-Linking Versus Small Incision Lenticule Extraction Only

Purpose

To evaluate clinical outcome during 24 months follow-up between small incision lenticule extraction combined with cross-linking (SMILE Xtra) and small incision lenticule extraction (SMILE) only. Setting. Ophthalmology Division of San Rossore Medical Center, Pisa, Italy.

Design

Retrospective comparative case series.

Methods

The study comprised 70 eyes (35 patients); 40 eyes were corrected using SMILE and 30 eyes were corrected using SMILE Xtra using a low energy protocol. The outcomes were compared at 1, 6, 12, and 24 months postoperatively.

Results

The mean spherical equivalent (SEQ) reduced from −7.18 ± 1.21 D to −0.01 ± 0.09 D in the SMILE group and from −6.20 ± 2.99 D to −0.04 ± 0.1 D postoperatively in SMILE Xtra (p < 0.05). At 24 months the mean SEQs were −0.01 ± 0.24 D for SMILE and −0.15 ± 0.33 D for SMILE Xtra (p > 0.05). At 1, 6, 12, and 24 months, there were no statistically significant differences between the SMILE and SMILE Xtra groups in logarithm of the minimum angle of resolution (logMAR) uncorrected distance visual acuity (UDVA), safety, and efficacy index (p > 0.05). The mean average keratometry (K-avg) at 1, 6, 12, and 24 months after surgery did not shown any statistically significant difference between SMILE and SMILE Xtra group (p > 0.05). The mean maximum keratometry (K-max) readings at 1, 6, 12, and 24 months were not statistically significant between SMILE and SMILE Xtra group (p > 0.05). The preoperative mean thinnest point pachymetry (TTP) was 543.90 ± 22.85 μm in the SMILE group and 523.40 ± 37.01 μm in the SMILE Xtra group (p < 0.05). At 1, 6, 12, and 24 months the mean TTP was not statistically significant between the SMILE and SMILE Xtra groups (p > 0.05). At 24 months, the TTP was 408.29 ± 38.75 μm for the SMILE group and 402.22 ± 37 μm for the SMILE Xtra group (p > 0.05). In the preoperative period, the mean maximum posterior elevation (MPE) was 8.63 ± 4.35 μm for SMILE and 8.13 ± 2.54 μm for SMILE Xtra (p > 0.05). After the surgical procedure, both groups showed a statistically significant increase of the MPE (p < 0.05). At 24 months, the MPE was 11.00 ± 4.72 μm for SMILE Xtra and 10.14 ± 3.85 μm for the SMILE group (p > 0.05). In the preoperative period, the means of the root mean square (RMS) of high-order aberration (HOA) were 0.08 ± 0.03 μm for the SMILE group and 0.08 ± 0.03 μm for the SMILE Xtra group (p > 0.05). At 24 months, the RMS of HOA was 0.13 ± 0.07 μm for the SMILE group and 0.14 ± 0.07 μm for the SMILE Xtra group (p > 0.05). In the preoperative period, the root mean square of coma aberration (RMS-Coma) aberration was 0.06 ± 0.09 μm for the SMILE group and 0.04 ± 0.03 μm for the SMILE Xtra group (p > 0.05). At 24 months, the coma aberration of SMILE group was 0.12 ± 0.21 μm and 0.16 ± 0.25 μm for SMILE Xtra group (p > 0.05).

Conclusions

SMILE Xtra procedure is a safe and simple procedure that can be offered to patients with high corneal ectasia risk because there were no differences in the indices of ectasia compared to the group treated only with SMILE which has a low corneal ectatic risk.

Posterior chamber toric implantable collamer lenses vs LASIK for myopia and astigmatism: systematic review

This systematic review compares the visual and refractive outcome of laser in situ keratomileusis with (toric) implantable collamer lens (ICL) in the treatment of myopic astigmatism. An electronic literature search led to 19 comparative articles. Refractive outcome, efficacy, safety, predictability, and stability as well as differences in contrast sensitivity and higher-order aberrations (HOAs) were analyzed for moderate (-3 to -6 diopters [D]) and high (≥-6 D) myopia. Results were either significantly in favor of (toric)-ICL or equal. Fewer HOAs and better contrast sensitivity after (toric)-ICL seem to be the largest asset in its refractive and clinical superiority. However, longer follow-up studies are indicated, specifically for systematically comparing long-term adverse effects.

[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.

Long-term longitudinal changes in axial length in the Caucasian myopic and hyperopic population with a phakic intraocular lens

Purpose

To determine the long‐term longitudinal axial length changes in myopic and hyperopic adults with an iris‐fixated phakic intraocular lens (pIOL).

Methods

The medical records of patients aged ≥18 years with myopia or hyperopia who were treated with pIOL implantation between 1996 and 2011 for refractive correction with a minimum follow‐up of 5 years after pIOL implantation were analyzed. The main outcome measure was change in ocular axial length over time.

Results

149 eyes of 149 myopic patients and 27 hyperopic eyes of 27 patients were included in this study. Mean patient age was 37.1 ± 10.4 years (35% male) in the myopic group and 39.4 ± 9.4 years (4% male) in the hyperopic group. The eyes of the myopic patients showed a significant mean increase in axial length of 0.45 ± 0.61 mm after a mean follow‐up time of 144 ± 38 months (p < 0.001). In 26 eyes (17%), the axial length had increased by ≥1 mm. The mean annual axial length increase was 0.04 ± 0.06 mm. Axial elongation was associated with a higher degree of myopia (p < 0.001) and younger age (p = 0.02). The eyes of the hyperopic patients showed no change in axial length over time.

Conclusions

Myopic eyes corrected with an iris‐fixated pIOL show continuous increase in axial length at an adult age. Although this study is limited to subjects with a pIOL, this is the first time myopization in Caucasian adults has been reported in a large long‐term longitudinal study.

Three-Year Follow-Up of Laser In Situ Keratomileusis Treatments for Myopia: Multi-Center Cohort Study in Korean Population

This multi-center cohort study included 3401 myopic laser in situ keratomileusis (LASIK) procedures conducted in 1756 myopia patients between 2002 and 2005. Pre- and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and manifest refraction spherical equivalent (SE) were recorded. Factors predicting low postoperative efficacy (defined as a postoperative UCVA < 0.5) were identified using univariate and multivariate logistic regression analysis. Compared with 1 month postoperatively, logMAR UCVA at 3 months postoperatively was significantly decreased (p = 0.002) and that at 2 and 3 years was significantly increased (p < 0.001). LogMAR BCVA at 2 years postoperatively was significantly decreased compared with 1 month postoperatively (p = 0.008). Over the 3-year postoperative period, overall refractive predictability within ±1.00 D and ±0.50 D ranged from 69.0% to 86.2% and from 43.3% to 67.8%, respectively. This also decreased from 1 month to 6 months postoperatively (p < 0.005). Multivariate logistic regression analysis using generalized estimating equations, revealed that higher preoperative SE (odds ratio [OR], 2.58 and 7.23; p < 0.001) and lower preoperative BCVA (OR, 2.44; p = 0.003) were predictive of a low postoperative efficacy. In summary, myopic LASIK can be effective and safe with a high refractive predictability in a Korean population, but myopic regression occurs over time. Higher preoperative SE and lower preoperative BCVA are predictive of a low postoperative efficacy.

Comparison of posterior corneal elevation after SMILE and FS-LASIK in correcting myopia over -9.0 diopters

Background

To compare the changes in posterior corneal elevation after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in correcting myopia over -9 diopters (D).

Methods

In this prospective comparative study, 82 eyes of 82 patients scheduled for refractive correction were recruited. Eyes were randomly assigned to the SMILE group (45 eyes, -10.43±0.92 D) or FS-LASIK group (37 eyes, -10.97±1.37 D). The posterior corneal surface was measured using a Scheimpflug camera (Pentacam, Oculus, Germany) preoperatively and at 1 day, 1 month, and 6 months after surgery. Posterior corneal elevation in the central point and central 4-mm area, and in various optical zones above the best-fit sphere, was analyzed. A P value of less than 0.05 was considered statistically significant.

Results

All surgeries were completed successfully. The safety index and efficacy index were 1.20 and 1.00, respectively, in the SMILE group, and was 1.10 and 0.90, respectively, in the FS-LASIK group. No significant difference existed in all analyzed data before and at 6 months after surgery in both the SMILE group and the FS-LASIK group. Changes in posterior corneal elevation after FS-LASIK were greater than after SMILE, with no statistical significance (P≥0.07). In the SMILE group, residual bed thickness was found to be moderately negatively correlated with changes in the elevation in the central area (P≤0.045); whereas it was positively correlated in the peripheral area (P=0.002).

Conclusions

SMILE and FS-LASIK presented stable posterior corneal surface in correction of myopia over -9.0 D at the follow-up visit of 6 months.

Is the axial length a risk factor for post-LASIK myopic regression?

PURPOSE

To assess the relationship between the axial length and post-LASIK regression in myopic patients.

METHODS

This is a retrospective case series study conducted at a private eye centre, Ismailia, Egypt. The clinical records of the patients, who experienced LASIK to correct myopia from January 2016 to January 2018, were analysed for myopic regression. The patients were operated on, examined, and followed-up 1 year by one surgeon (AAG).

RESULTS

This study included 1219 patients (2316 eyes) with myopia. Mean ± SD of pre-operative spherical equivalent (SE) was - 4.3 ± 2.1D, range (- 0.50 to - 10.0D). Mean ± SD age of the patients was 26.4 ± 6.8 years, range (21 to 50 years). Male to female ratio was 30.5 to 69.5%. The cumulative incidence rate of myopic regression according to the medical records of the patients was 25.12% (582 eyes out of total 2316 eyes) along the 2 years of this study (12.6% per year). Of the total patients, 14.94% had pre-operative high myopia, 35.84% had pre-operative moderate myopia, and 49.2% had pre-operative low myopia. Of the patients with myopic regression, 52.6% had pre-operative high myopia, 34% had pre-operative moderate myopia, and 13.4% had pre-operative low myopia. The mean ± SD of the axial length of the patients with myopic regression was 26.6 ± 0.44 mm, range (26.0 to 27.86 mm), while the mean ± SD of the axial length of other patients with stable refraction was 24.38 ± 0.73 mm, range (22.9 to 25.9 mm) (t test statistic = 69.3; P value < 0.001).

CONCLUSIONS

Pre-operative high axial length increases the risk of myopic regression after LASIK.

Patient-reported vision-related quality of life after laser in situ keratomileusis, surface ablation, and phakic intraocular lens: The 5.5-year follow-up study

To evaluate the long-term efficacy of refractive surgery of all cases in a single center via the use of a patient-reported outcome (PRO) refractive status questionnaire using descriptive statistics. This study was prospective, single-center, cohort study that involved 1422 patients who underwent refractive surgery (laser in situ keratomileusis, surface ablation, and phakic intraocular lens) at Baptist Eye Institute, Kyoto, Japan. The patients were asked to answer the Refractive Status and Vision Profile (RSVP) questionnaire before the surgery after 6 months (n = 1133 patients) and after 5.5 years (n = 232 patients). During the same period, examination by slit-lamp biomicroscopy and visual acuity tests were performed. Moreover, the patients were asked to rate their satisfaction with the surgery 6 months and 5.5 years after it. We examined overall RSVP scale (S), 8 RSVP subscales, rate of satisfaction with surgical outcome, slit-lamp biomicroscopy findings, and refractive error. The mean preoperative S was 36, yet that score significantly improved to 19 at 6 postoperative months postoperatively (P < .01), and basically remained the same (i.e., 20) throughout the 5.5-year postoperative period. During the 5-year follow-up period, mean refractive error became slightly myopic (0.3 D). No change in the rate of satisfaction was observed at both 6 months and 5.5 years postoperative period. The findings of this study help to clarify long-term PRO quality of vision (QOV) postrefractive surgery in a single center, and show that minor change in refractive error during 5 years postoperative period had no influence on the mean RSVP scores among outpatients. Nearly all patients reported short-term improvement of QOV, which continued throughout the long-term follow-up period.

10-Year Results of FLEx Refractive Surgery

PURPOSE

To evaluate the 10-year results of femtosecond lenticule extraction (FLEx) for treatment of myopia and myopic astigmatism.

METHODS

This long-term follow-up of a prospective clinical trial was conducted at HELIOS Klinikum Erfurt and Phillips University of Marburg, Germany. In 2006, 108 eyes underwent the FLEx procedure. All patients were invited for reexamination 10 years after FLEx treatment for myopia and astigmatism. Visual acuity, objective and manifest refraction, intraocular pressure, and slit-lamp examination and side effects were documented. Main outcome measures were uncorrected (UDVA) and corrected (CDVA) distance visual acuity, objective and manifest refraction, and slit-lamp examination and side effects.

RESULTS

A total of 77 eyes of 40 patients of the original treatment group volunteered for a reexamination 10 years after surgery. The mean age of the patients was 45.9 years; 26 were women and 14 were men. UDVA was 0.09 ± 0.19 logMAR and CDVA was stable at -0.1 ± 0.09 logMAR. More than half of the eyes gained one or two Snellen lines, and none of the eyes lost two or more lines. Over the 10-year period, regression was 0.18 D.

CONCLUSIONS

FLEx has stable results 10 years after treatment for myopia and astigmatism. [J Refract Surg. 2019;35(11):707-711.].

Laser flap enhancement 5 to 9 years and 10 or more years after laser in situ keratomileusis: Safety and efficacy

PURPOSE

To study the safety and efficacy of refractive enhancement by flap lifting 5 and 10 years after laser in situ keratomileusis (LASIK).

SETTING

Vissum Alicante, Spain.

DESIGN

Retrospective case series.

METHODS

Eyes with a flap lift at least 5 years after primary LASIK with a 3-month follow-up were evaluated. The primary outcome measures were safety and the complication rate. Moderate epithelial ingrowth was managed with Nd:YAG laser treatment.

RESULTS

The primary LASIK procedure was myopic in 45 eyes, hyperopic in 22 eyes, and presbyopic in 3 eyes. The mean time from primary LASIK to the flap lift was 12.3 years ± 3.45 (SD). In 57 eyes, the primary LASIK flap was created at least 10 years before the enhancement. The mean pre-lift spherical equivalent was -1.29 ± 1.23 diopters (D) in the myopia group and +0.65 ± 1.72 D in the hyperopia group. Three months later, 88% of eyes and 74% of eyes, respectively, had an uncorrected distance visual acuity of 20/20 or better; 100% achieved at least 20/25. No eye lost 2 lines or more of corrected distance visual acuity. In the myopia group, the efficacy index was 0.94 and the safety index was 0.98 at 6 months. Mild epithelial ingrowth developed in 31.43% of eyes and clinically significant epithelial ingrowth in 11.42% of eyes; 4.28% required a relift for severe epithelial ingrowth.

CONCLUSIONS

Late flap lift for refractive enhancement 10 years or more after LASIK provided good efficacy and safety with fast visual recovery. The rate of surgical intervention for significant postoperative epithelial ingrowth was low.

Corneal refractive surgery combined with simultaneous corneal cross-linking: Indications, protocols and clinical outcomes-A review

Corneal refractive surgery is one of the most common approaches for correction of refractive errors. Combined corneal refractive surgery and corneal cross-linking (CXL) has been proposed as a method to achieve better refractive stability and to prevent iatrogenic corneal ectasia. However, there are concerns regarding its indications, surgical safety, standardization of protocols and long-term effect on corneal tissue. This review article aims to discuss the current knowledge and recent updates on combination of CXL and refractive surgery.

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.

Effect of age on visual and refractive results after LASIK: mechanical microkeratome versus femtosecond laser

AIM

To evaluate the effect of age on visual and refractive results after laser in situ keratomileusis (LASIK) obtained with a mechanical microkeratome or a femtosecond laser.

METHODS

Retrospective, nonrandomized, cohort study. A total of 3826 eyes were included in the study (1725 eyes treated with mechanical LASIK and 2101 eyes treated with femtosecond LASIK). The relationship between patient age and the 3-month postoperative visual and refractive results of both procedures were analyzed by linear regression analysis.

RESULTS

Three months postoperatively, we found a significant correlation between age and the postoperative spherical equivalent (SE; r ²=0.004, P=0.006), efficacy (r ²=0.006, P=0.001), and safety indexes (r ²=0.05, P=0.0001) in the mechanical LASIK group. On the other hand, we found a significant correlation between age and the postoperative SE (r ²=0.02, P=0.0001) and the efficacy index (r ²=0.01, P=0.0001) but not the safety index in the femtosecond laser group. Mechanical LASIK provided slightly but significantly better efficacy and predictability in patients 18 to 40 years of age and femtosecond LASIK did so in patients older than 40 years of age. The femtosecond laser provided better safety results than the mechanical microkeratome in both age groups.

CONCLUSION

A tendency toward undercorrection and less predictability is found with aging after myopic LASIK regardless of whether the flap was created with a mechanical microkeratome or a femtosecond laser. However, femtosecond laser provides significantly better outcomes in terms of efficacy, safety and predictability compared to mechanical microkeratome for the correction of myopia in patients over 40y.

Femtosecond-assisted laser in situ keratomileusis for high myopia correction: Long-term follow-up outcomes

OBJECTIVE

Report the outcomes of laser in situ keratomileusis (LASIK) for high myopia correction after long-term follow-up.

METHODS

Retrospective, consecutive, clinical study including 70 eyes that underwent LASIK using a 500 Hertz (Hz) repetition rate excimer laser and femtosecond technology for flap creation. Visual, refractive, corneal aberrations, and correlation among the variables were evaluated during 3 years. In addition, 34 eyes were followed during 5 years.

RESULTS

Significant improvement of 17 logMAR lines was observed in uncorrected vision at 5 years (p < 0.01). This was consistent with spherical equivalent reduction that came from mean preoperative -7.79 diopters (D) to 5 years postoperative -0.24 D (p < 0.01). Significant induction of primary spherical aberration and coma aberration was also found (p < 0.01) at 3 months with levels of 0.61 µm and 0.47 µm, respectively, with no further changes at 5 years (p > 0.05). Pearson correlation showed that the amount of high-order aberrations at 3 months postoperativeley was significantly correlated with the changes in the keratometry throughout the 5 years (delta K) (R2 0.242 p = 0.05). Finally, preoperative corneal asphericity showed an inverse correlation with the delta K (R2 -308 p = 0.01).

CONCLUSIONS

Results from this study suggests that LASIK for high myopia correction using 500 Hz repetition rate excimer laser provides stable visual, refractive and aberrometric results after 5 years of follow-up. A more prolate cornea and the amount of higher-order aberrations induced after LASIK are factors that negatively impact in the long-term stability of the procedure.

Comparison of changes in refractive error and corneal curvature following small-incision lenticule extraction and femtosecond laser-assisted in situ keratomileusis surgery

Purpose

To compare visual acuity, refractive error, corneal curvature, and the stability of these parameters during the early postoperative period following small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) surgery.

Methods

One hundred and five eyes and 110 eyes were enrolled in SMILE and FS-LASIK group, respectively. Uncorrected and best-corrected distance visual acuity (UCVA and BCVA), manifest refraction, corneal curvature, intraocular pressure, and slit-lamp examinations were performed preoperatively, 1 day, 1 week, 1 month, and 3 months postoperatively.

Results

No significant differences in postoperative UCVA or BCVA were observed between the SMILE and FS-LASIK groups at any time point. SMILE group had significant better postoperative spherical equivalent (SE) values than FS-LASIK group at 1 day, 1 week, and 1-month follow-up. However, there was no significant difference in postoperative SE values at 3-month follow-up. Significant differences in mean postoperative corneal curvature were observed during all follow-up examinations.

Conclusion

SMILE surgery was associated with more accurate postoperative refractive correction up to 1 month following surgery. SMILE surgery also resulted in less significant corneal curvature changes than FS-LASIK. Furthermore, FS-LASIK was associated with decreased stability of postoperative refractive error and corneal curvature relative to SMILE.

Eighteen-year prospective audit of LASIK outcomes for myopia in 53 731 eyes

BACKGROUND

To assess the outcomes of laser-assisted in situ keratomileusis (LASIK) performed for the treatment of myopia in terms of safety, efficacy and predictability in an 18-year clinical audit.

METHOD

In this single-centre, prospective, non-randomised study, preoperative and postoperative refractions, uncorrected (UCVA), best-corrected Snellen visual acuity (BCVA) and complications of all eyes undergoing myopic LASIK were recorded. Safety, efficacy, refractive predictability, treatment trends, retreatment rates and complication rates were evaluated.

RESULTS

Between 1998 and 2015, 53 731 eyes of 27312 patients underwent myopic LASIK. Patients' median age was 31.6 years (mean, 32.6±7.3 years); there were 9703 males (35.5%). Patients were predominantly ethnic Chinese (87.4%). Mean follow-up time was 78±75.6 days (median, 86 days). Overall efficacy index was 0.91 with >99% of eyes achieving UCVA of ≥20/40 and >70% achieving 20/20 since 2010. 95.43% of eyes had no loss of vision postoperatively and 4.2% and 0.37% lost 1 and ≥2 lines BCVA, respectively. From 2010 the safety index has been >1.05. More than 94.0% of eyes achieved within ±1.0 D of target refraction and at least 70% achieved within ±0.50 D of target from 2010 onwards. Retreatment rate was 2.55% and after retreatment 98.4% of eyes achieved ≥20/40 UCVA and 63.5% achieved ≥20/20 UCVA. The overall complication rate is 0.98%, and since 2010, the annual complication rate has been <0.8%.

CONCLUSIONS

Myopic LASIK performed in Asian eyes is safe and effective with high refractive predictability in a comprehensive LASIK programme with appropriate clinical audit.

Refractive regression after laser in situ keratomileusis

Uncorrected refractive errors are a leading cause of visual impairment across the world. In today's society, laser in situ keratomileusis (LASIK) has become the most commonly performed surgical procedure to correct refractive errors. However, regression of the initially achieved refractive correction has been a widely observed phenomenon following LASIK since its inception more than two decades ago. Despite technological advances in laser refractive surgery and various proposed management strategies, post-LASIK regression is still frequently observed and has significant implications for the long-term visual performance and quality of life of patients. This review explores the mechanism of refractive regression after both myopic and hyperopic LASIK, predisposing risk factors and its clinical course. In addition, current preventative strategies and therapies are also reviewed.

Clinical evaluation of a new correction algorithm for dynamic Scheimpflug analyzer tonometry before and after laser in situ keratomileusis and small-incision lenticule extraction

PURPOSE

To compare a biomechanically corrected intraocular pressure (bIOP) algorithm provided by the dynamic Scheimpflug analyzer (Corvis ST) with Goldmann applanation tonometry IOP (Goldmann IOP) and standard dynamic Scheimpflug analyzer IOP measurements before and after laser in situ keratomileusis (LASIK) and refractive lenticule extraction small-incision lenticule extraction (SMILE) surgeries.

SETTING

Smile Eye Clinic, Munich, Germany, and University of Liverpool, Liverpool, United Kingdom.

DESIGN

Retrospective case series.

METHODS

Patients scheduled for LASIK and patients scheduled for small-incision lenticule extraction for myopia or myopic astigmatism were included. The preoperative and postoperative evaluations included Goldmann, Scheimpflug tomography, and dynamic Scheimpflug analyzer IOP measurements.

RESULTS

The study comprised 14 patients in the LASIK group and 22 patients in the small-incision lenticule extraction group. Preoperative Goldmann IOP and Scheimpflug analyzer IOP values showed significant positive correlation with central corneal thickness (CCT) (P = .05 for LASIK; P = .003 for small-incision lenticule extraction). No significant correlation was found between bIOP and CCT (P > .05). After both surgeries, there were significant decreases in Goldmann IOP (-3.2 mm Hg ± 3.4 [SD] and -3.2 ± 2.1 mm Hg, respectively; both P < .001) and Scheimpflug analyzer IOP (-3.7 ± 2.1 mm Hg and -3.3 ± 2.0 mm Hg, respectively, both P < .001) compared with preoperative readings, whereas bIOP did not differ significantly (0.1 ± 2.1 mm Hg and 0.8 ± 1.8 mm Hg, respectively; P = .80 and P = .273, respectively).

CONCLUSIONS

The bIOP readings before and after LASIK and small-incision lenticule extraction were neither significantly different nor correlated with CCT. In contrast, both Goldmann IOP and Scheimpflug analyzer IOP had significant reductions postoperatively and showed significant correlation with CCT preoperatively.

Posterior corneal surface differences between non-laser in situ keratomileusis (LASIK) and 10-year post-LASIK myopic eyes

PURPOSE

To evaluate the posterior corneal surface differences between non-laser in situ keratomileusis (LASIK) and 10-year post-LASIK myopic eyes.

METHODS

The study included 130 eyes from 65 patients, who were treated with myopic LASIK 10 years ago. In addition, 130 eyes from 65 unoperated myopic patients of matching present age and preoperative refraction were divided into control group. Data on the posterior corneal surface and anterior chamber were obtained from Pentacam software and compared between the groups. Postoperative visual acuity (VA) and refractive error were also analysed.

RESULTS

The mean preoperative spherical equivalent (SE) was -6.99 ± 1.78 dioptre (D) in the LASIK group. Ten years after surgery, the mean SE was -0.45 ± 1.22 D, the efficacy index was 0.98, and the safety index was 1.01. The posterior corneal elevations of the LASIK group at 2 mm corneal diameter were significantly lower than those of the control group. However, posterior corneal elevations at 6 mm corneal diameter were higher in the LASIK group than the controls (p < 0.01 for all). The mean Q-values of posterior corneal surface demonstrated significant positive direction compared to that of control eyes at 6 and 7 mm corneal diameters (p < 0.05 for both). At the thinnest point of the cornea, the anterior chamber depths were shallower in the LASIK group than in controls. Meanwhile, the anterior chamber volumes (ACV) were smaller in the LASIK group than in the control group.

CONCLUSION

Our results demonstrated that the posterior corneal surface tends to show signs of central flattening and peripheral steepening 10 years after myopic LASIK surgery compared to that of non-operated myopic eyes.

Femtosecond laser-assisted sub-Bowman keratomileusis versus laser-assisted subepithelial keratomileusis to correct myopic astigmatism

PURPOSE

To compare femtosecond laser-assisted sub-Bowman keratomileusis (FSBK) versus laser-assisted subepithelial keratomileusis (LASEK) to correct moderate to high myopic astigmatism.

METHODS

Retrospective, nonrandomized, interventional, comparative case series. A total of eight hundred and fifty-two eyes with myopic astigmatism of -1.5 diopters (D) or higher were included in the study. We compared 427 eyes treated with FSBK versus 425 eyes treated with LASEK with or without mitomycin C. Visual and refractive results were evaluated 1 day, 1 week, 3 and 6 months postoperatively.

RESULTS

Six months postoperatively, the residual spherical defect was slightly but significantly higher in the LASEK group (+0.15±0.62D) than in the FSBK group (+0.09±0.35D) (P=0.05). The postoperative residual astigmatism was also slightly but significantly higher in the LASEK group (-0.38±0.52D) than in the FSBK group (-0.26±0.45D) (P=0.0005). No significant differences were found in the efficacy (0.98±0.17 versus 0.98±0.36, P=0.6) and safety indexes (1.04±0.16 versus 1.05±0.37, P=0.1) between FSBK and LASEK. The enhancement rate was significantly higher in the FSBK group (22.6%) than in the LASEK group (15.5%) (P=0.01).

CONCLUSIONS

Both FSBK and LASEK are safe and effective procedures to correct moderate to high myopic astigmatism. Slightly better visual and refractive results were observed in FSBK-treated eyes in a 6-month follow-up.

Combined application of prophylactic corneal cross-linking and laser in-situ keratomileusis - a review of literature

Laser in-situ keratomileusis (LASIK) is safe and effective laser refractive procedures in treating refractive errors. However, regression of treatment and iatrogenic keratectasia remain to be a major concern, especially in treating thin cornea with high ametropia. Collagen cross-linking (CXL) is an effective method in stopping keratoconus progression through increasing the biomechanical strength of the cornea. Adjuvant cross-linking to refractive procedures can theoretically help prevent regression and reduce the risk of keratectasia development by increasing the mechanical stability of cornea. During the procedure, riboflavin is directly applied to the corneal stroma, thereby reducing the need of de-epithelialization as in the conventional protocol for keratoconus. Currently, there is still no consensus regarding the indication of CXL during refractive procedure, nor any standardized treatment protocol. This article aims to summarize the current evidence regarding the use of adjuvant CXL in LASIK.

Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia

Purpose

To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia.

Methods

We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (−3.00 to −12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events.

Results

The safety and efficacy indices were 0.82 ± 0.29 and 0.67 ± 0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of −0.74 ± 0.99 D occurred from 3 months to 12 years after LASIK (p < 0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient, r = −0.28, p = 0.02), but not with the changes in central corneal thickness (r = −0.08, p = 0.63). No vision-threatening complications occurred in any case.

Conclusions

Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening.

Myopic Surface Ablation in Asymmetrical Topographies: Refractive Results and Theoretical Corneal Elastic Response

PURPOSE

To evaluate refractive results and the theoretical elastic response of photorefractive keratectomy in eyes with asymmetrical corneal surface and to compare such outcomes with a control-matched group of normal topographies.

DESIGN

Retrospective interventional case series with matched comparison group.

METHODS

Thirty eyes with superior-inferior dioptric difference (SI index) > 1.40 diopter (D) were compared to 30 eyes with normal topographies. Both groups were matched for age, preoperative spherical equivalent (SE), mean keratometry, and percentage of tissue altered (PTA). Refractive results and the theoretical elastic modulus calculations were evaluated.

RESULTS

The mean preoperative SI index in the asymmetrical group was 2.06 ± 0.56 D vs 0.14 ± 0.73 D in the control group (P < .001). From 3 to 12 months postoperatively, the asymmetrical group presented a mean re-steepening of 0.51 ± 0.39 D vs 0.19 ± 0.40 D in the control group (P = .014). The mean PTA of 14.42% generated a theoretical elastic modulus reduction of 10.25% in the asymmetrical group vs 2.45% in the control group (P = .006). The reduction of the theoretical elastic modulus correlated with the preoperative SI index (ρ = -0.387, P = .007). After 36 months, 90% of all eyes were within ±0.50 D of SE and the theoretical elastic modulus did not present a significant difference between both groups (P = .085).

CONCLUSIONS

Asymmetrical-topography corneas treated with myopic surface ablation presented an increased short-term keratometric re-steepening and reduction of the theoretical elastic moduli. The long-term follow-up indicated that, in selected cases of asymmetrical topographies, myopic surface ablation could induce a premature biomechanical elastic response rather than a progressive pathologic process.

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.

Effect of incision types for Artisan phakic intraocular lens implantation on ocular higher order aberrations

AIM

To evaluate the effect of incision types for Artisan phakic intraocular lens (PIOL) implantation on ocular higher-order aberrations (HOAs).

METHODS

A retrospective review was conducted of the patients who had undergone Artisan PIOL implantation for the correction of myopia and followed up for at least 6mo. Patients are classified into 2 groups considering the incision type: cornea group with patients undergone clear corneal incision; sclera group with patients undergone sclera tunnel incision. All patients with postoperative astigmatism of under 1 diopter (D) were included to minimize the effect of residual astigmatism on postoperative HOAs. Visual acuity, special equivalents, astigmatism, predictability (±1 D from target refraction), HOAs (coma, trefoil, spherical aberration), and corneal endothelial counts were analyzed preoperatively and 6mo postoperatively.

RESULTS

At the postoperative 6mo, all patients of both groups achieved uncorrected visual acuity of 16/20 or better, and significantly decreased the spherical equivalents compared with preoperative values. The predictability of refractive correction was 96% in the former, and 94% in the latter. Unlike the sclera group, preoperative astigmatism decreased significantly in cornea group at postoperative 6mo. The HOAs increased significantly at postoperative 6mo compared to the preoperative values in both groups, and the root mean square (RMS) total and trefoil wavefront aberration of cornea group were significantly higher than those of sclera group.

CONCLUSION

Although corneal incision significantly reduces preexisting astigmatism, the postoperative 6mo of total RMS and trefoil aberration change may deteriorate the visual quality after Artisan PIOL implantation.

Outcomes of photorefractive keratectomy following laser in situ keratomileusis: a cohort study

OBJECTIVE

To analyze the outcomes of photorefractive keratectomy (PRK) on residual myopia and hyperopia post-laser in situ keratomileusis (LASIK) and to compare these results with PRK on eyes without previous laser refractive surgery.

DESIGN

Retrospective comparative cohort study.

PARTICIPANTS

Patients undergoing PRK between 2006 and 2010 were reviewed.

METHODS

Patients were divided into 4 groups, myopic or hyperopic PRK post-LASIK (mPRK-PL and hPRK-PL, respectively) and myopic or hyperopic PRK on corneas without previous laser refractive surgery (mPRK and hPRK, respectively). Uncorrected and corrected distance visual acuity, mean refractive spherical equivalent (MRSE), and mean keratometry and aberrations (total, higher order [HOA], coma, trefoil, and spherical aberration) were recorded at months 3 and 6 postoperatively, as were complications and attempted versus achieved MRSE.

RESULTS

Thirty-three eyes of 25 patients who underwent PRK post-LASIK (21 eyes of 14 patients for hPRK-PL and 12 eyes of 11 patients for mPRK-PL) and 35 eyes of 21 patients who underwent PRK on virgin eyes (11 eyes of 8 patients for hPRK and 24 eyes of 13 patients for mPRK) were included in the study. The only significant differences in outcomes were found to be HOA at 3 months for hPRK-PL as compared with both hPRK and mPRK. Achieved MRSE was significantly different from expected MRSE for hPRK-PL at 3 months postoperatively. No haze- or flap-related complications were observed.

CONCLUSION

Outcomes of PRK were not different in myopic and hyperopic corrections post-LASIK by 6 months or when compared with PRK in virgin eyes. HOA may render hPRK-PL results less predictable early in the postoperative period.

Four-year observation of predictability and stability of small incision lenticule extraction

BACKGROUND

To investigate long-term refractive outcomes, wavefront aberrations and quality of life after small incision lenticule extraction (SMILE) for moderate to high myopia.

METHODS

A total of 26 patients (47 eyes) with preoperative mean spherical equivalent (SE) of -6.30 ± 1.47 diopters (D) who underwent SMILE were recruited. The measurements included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, wavefront aberrations, and quality of life.

RESULTS

At 4 years postoperatively, UDVA was better than or equal to 20/20 in 92 % of eyes. The efficacy index was 1.07 ± 0.16. 89 % of eyes were within ± 0.5 D of the intended refractive target. No eye lost any Snellen lines. The safety index was 1.16 ± 0.14. No significant changes of SE occurred among postoperative follow-ups at months 1, 3, 6 and years 1, 2, 4 (P > 0.05, Scheffe test). Higher-order aberrations, coma, spherical aberration and higher-order astigmatism increased postoperatively, and no significant changes of aberrations were detected among the 1-month, 6-month or 4-year follow-ups postoperatively (37 eyes). Compared to the spectacles group, the surgery group showed a significantly higher total score on quality of life (45.71 ± 2.61 vs 39.96 ± 3.56, P < 0.001).

CONCLUSIONS

SMILE provides a predictable and stable correction of moderate to high myopia as documented by long-term follow-up.

Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia

Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra) with SMILE. Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively. Results. Both groups had myopia with spherical equivalent refraction (SEQ) > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p < 0.021). At 6 months, no eyes lost more than 1 line in corrected distance visual acuity. The safety index was 0.96 ± 0.06 and 1.00 ± 0.00 in SMILE Xtra and control, respectively (p < 0.001). 89% and 94% of eyes were within ±0.50 D of target refraction, respectively, with the mean error in SEQ correction being −0.17 ± 0.26 D for SMILE Xtra and +0.03 ± 0.25 D for control (p = 0.021). The efficacy index was 0.88 ± 0.13 and 0.97 ± 0.06, respectively (p = 0.005). Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

Long-term evaluation of eyes with central corneal thickness <400 μm following laser in situ keratomileusis

Purpose

To study long-term refractive and visual outcomes of laser in situ keratomileusis (LASIK) in eyes with a postoperative thin central cornea.

Methods

In this retrospective observational case series, we studied 282 myopic eyes with a normal preoperative topographic pattern and postoperative thin corneas (<400 μm) that had at least 3 years of follow-up after LASIK in three private clinics. The main outcome measures were safety, efficacy, predictability, percent tissue altered, and complications.

Results

The mean postoperative central corneal thickness was 392.05 μm (range: 363.00–399.00 μm). After a mean follow-up of 6.89±2.35 years (standard deviation), the safety index was 1.17, the efficacy index was 0.94, and predictability (±1.00 diopter [D]) was 73.49. The mean residual stromal bed thickness was 317.34±13.75 μm (range: 275–356 μm), the mean flap thickness was 74.76±13.57 μm (range: 55–124 μm), and the mean percent tissue altered was 37.12%±3.62% (range: 27.25%–49.26%). No major complications were recorded.

Conclusion

LASIK with a resultant central cornea thickness <400 μm seems to be effective, safe, and predictable provided that preoperative topography is normal and the residual stromal bed thickness is >275 μm.

Combined laser in situ keratomileusis and prophylactic high-fluence corneal collagen crosslinking for high myopia: two-year safety and efficacy

PURPOSE

To evaluate the safety, efficacy, and refractive and keratometric stability of myopic femtosecond laser in situ keratomileusis (LASIK) with concurrent prophylactic high-fluence corneal collagen crosslinking (CXL) compared with the outcomes of standard femtosecond LASIK.

SETTING

Private clinical practice, Athens, Greece.

DESIGN

Consecutive randomized prospective comparative study.

METHODS

Eyes that had myopic LASIK or myopic LASIK with concurrent high-fluence CXL were evaluated preoperatively and up to 2 years postoperatively for manifest refraction spherical equivalent (MRSE), refractive astigmatism, visual acuity, corneal keratometry (K), and endothelial cell count.

RESULTS

One hundred forty consecutive eyes had myopic LASIK; 65 of the eyes were treated additionally with CXL. In the LASIK-CXL eyes, the mean postoperative MRSE was -0.18 diopter (D) ± 17.0 (SD) from -6.67 ± 2.14 D preoperatively. The postoperative flat K was 37.67 D from 43.92 D, and the steep K was 38.38 D from 45.15 D. The correlation coefficient of SE correction predictability was 0.975. In the LASIK-only eyes, the mean postoperative MRSE was -0.32 ± 0.24 D from -5.49 ± 1.99 D preoperatively. The flat K was 38.04 D from 43.15 D, and the steep K was 38.69 D from 44.03 D. The correlation coefficient of SE correction predictability was 0.968. The differences between the 2 groups at the 20/20 and 20/25 levels were statistically significant (P = .045 and P = .039, respectively).

CONCLUSION

Two-year results indicate that the application of prophylactic CXL concurrently with high-myopic LASIK appears to improve refractive and keratometric stability, presumably by affecting corneal biomechanical properties.

FINANCIAL DISCLOSURE

Dr. Kanellopoulos is a consultant to Alcon Surgical, Inc., Wavelight Laser Technologie AG, Allergan, Inc., Avedro, Inc., and i-Optics Corp. Dr. Asimellis has no financial or proprietary interest in any material or method mentioned.

In-vivo corneal biomechanical analysis of unilateral keratoconus

AIM

To evaluate and compare corneal biomechanical findings measured by ocular response analyzer, topographic and pachymetric findings in patients with unilateral keratoconus patients and healthy controls.

METHODS

This is an observational, case-control study. Patients with keratoconus in one eye and forme fruste keratoconus in the fellow eye were compared with sex and age matched with controls healthy subjects. All subjects were evaluated with rotating scheimpflug imaging system. The receiver-operating-characteristic curves were analyzed to evaluate the sensitivity and specificity of the parameters.

RESULTS

Twenty-seven patients with keratoconus in one eye and forme fruste keratoconus in the fellow eye were compared with 40 eyes of 40 normal subjects. Corneal hysteresis (CH) was 8.0±1.7 mm Hg in keratoconus group, 8.3±1.6 mm Hg in forme fruste keratoconus group, and 9.8±1.6 mm Hg in control groups (P=0.54 between keratoconus and forme fruste keratoconus groups, P<0.01 between control group and other groups). Corneal resistance factor (CRF) was 7.1±2.2 mm Hg in keratoconus group, 7.8±1.2 mm Hg in forme fruste keratoconus group and 9.9±1.5 mm Hg in control group (P<0.001 between control group and other groups). Using receiver-operating-characteristic analysis, the area under curve values of the parameters to distinguish forme fruste keratoconus from control subjects were: CH (0.768), CRF (0.866). Best cut-off points were 9.3 mm Hg and 8.8 mm Hg for CH and CRF respectively.

CONCLUSION

Ocular response analyzer parameters (CH and CRF) are found to be significantly lower in forme fruste keratoconus patients compared to normal control subjects.

Lasik Xtra® Provides Corneal Stability and Improved Outcomes

A new procedure which combines LASIK and corneal cross-linking (Lasik Xtra®) has been proposed as an alternative to traditional LASIK. It is aimed at restoring strength to the cornea, increasing stability in visual outcomes, increasing the accuracy of the refractive correction, and potentially lowering enhancement rates. This article reviews the current clinical evidence which has been published on the topic and reviews both the safety and efficacy argument for the procedure.

Corneal wound healing after laser vision correction

Any trauma can trigger a cascade of responses in tissues, with the purpose of safeguarding the integrity of the organ affected by the trauma and of preventing possible damage to nearby organs. Subsequently, the body tries to restore the function of the organ affected. The introduction of the excimer laser for keratorefractive surgery has changed the treatment landscape for correcting refractive errors, such as myopia, hyperopia, and astigmatism. In recent years, with the increased understanding of the basic science of refractive errors, higher-order aberrations, biomechanics, and the biology of corneal wound healing, a reduction in the surgical complications of keratorefractive surgery has been achieved. The understanding of the cascade of events involved in the corneal wound healing process and the examination of how corneal wound healing influences corneal biomechanics and optics are crucial to improving the efficacy and safety of laser vision correction.

Efficacy, predictability and safety of small incision lenticule extraction (SMILE)

BACKGROUND

The purpose of this case series is to report the one-year outcomes of small incision lenticule extraction (SMILE) using the VisuMax® femtosecond laser.

METHODS

Two hundred and six patients were recruited for this retrospective, single center study at TRSC International LASIK Center in Bangkok, Thailand. Patients underwent SMILE, whereby an intrastromal lenticule was cut using a femtosecond laser and then manually extracted without the need for flap creation. Outcome measures included refraction, visual acuity and contrast sensitivity evaluation. Patients were treated and followed for one year.

RESULTS

SMILE for the correction of low to high myopia was performed on 347 eyes of 206 patients. The mean preoperative spherical equivalent was -4.96 ± 1.88 diopters (D). On the first day following surgery, for eyes with a plano target refraction (99.14 % of all eyes), uncorrected distance visual acuity (UDVA) was 20/20 or better in 90 % of eyes. At the one week postoperative exam, the mean spherical equivalent was 0.01 ± 0.36 D and UDVA was 20/20 or better in 84 % of eyes. After one year follow-up, no eyes showed loss of 2 or more lines of visual acuity and 31 % of eyes gained one or more lines. The photopic contrast sensitivity of SMILE treated eyes at 12 and 18 cycles per degree (cpd) improved from 1.59 and 0.94 preoperatively to 1.6 and 0.98, respectively, after one year.

CONCLUSIONS

In this series, SMILE using the VisuMax® femtosecond laser demonstrated that after one year it is an effective, predictable and safe minimally invasive corneal refractive procedure.

3-Year follow-up after Lasik: assessing the risk factors for retreatment

The purpose of this study was to evaluate the correlation of important risk factors for LASIK retreatment and the retreatment rate. A retrospective cohort study was conducted. Records of patients who underwent LASIK between January 2011 and January 2012 at the Zambrano-Hellion Medical Center, Tec de Monterrey (México), and posteriorly underwent LASIK retreatment were identified and risk factors to receive retreatment were assessed using relative risk. Main outcomes were retreatment rate, risk factors for retreatment, and uncorrected distance visual acuity (UDVA). 482 eyes from 241 patients were available for a 36-month follow-up analysis. 68.5 % had primary myopic LASIK; 37 % were ≤ 2 diopters (D), 52 % were > 2 and < 6 D, and 11 % were ≥ 6 D of myopia. 31.5 % of the eyes had hyperopic LASIK. Retreatment was performed in 6.85 % eyes. Myopia > 6 D (RR 4.13), hyperopic refraction (RR 3.18), and age > 40 (RR 3.07) were the most important risk factors for retreatment (P = 0.004, P = 0.007, P = 0.006, respectively). UDVA was ≥ 20/40 in 92.1 % and ≥ 20/20 in 81.6 % of the retreated eyes and 82 % of the eyes within ± 0.50 D of target refraction. Increasing degrees of myopia, followed by hyperopic refraction, and age were the most important associated factors to retreatment. LASIK retreatment was safe and effective.

Longitudinal comparison of outcomes after sub-Bowman keratomileusis and laser in situ keratomileusis: randomized, double-masked study

PURPOSE

To compare the outcomes of sub-Bowman keratomileusis (100-μm flap) and laser in situ keratomileusis (LASIK) (120-μm flap) using 150-kHz femtosecond laser.

DESIGN

Randomized, double-masked, contralateral clinical trial.

METHODS

One hundred patients (200 eyes) with myopia or myopic astigmatism were included. Postoperative examinations were performed at week 1 and months 1, 3, 6, and 12. Main outcome measures included postoperative uncorrected (UCVA) and best-corrected distance visual acuity (BCVA); manifest refraction spherical equivalent; efficacy and safety indices; corneal thickness; and complications.

RESULTS

The mean age of patients was 33.9 ± 7.9 years. Overall, the preoperative UCVA, BCVA, and manifest refraction spherical equivalent were 1.349 ± 0.332, -0.022 ± 0.033, and -5.81 ± 1.61 diopters, respectively. No significant difference was observed in preoperative (P ≥ .226) or intraoperative parameters (P ≥ .452) between both groups, except residual stromal thickness (P < .001). The UCVA, manifest refraction spherical equivalent, and central corneal thickness stabilized by 1 week, while the thinnest corneal thickness stabilized by 3 months postoperatively. There was no significant difference between both groups for any parameter during all follow-up visits (P ≥ .132) except the 3-month safety index, which was better in the sub-Bowman keratomileusis group (P = .007). Soft opaque bubble layer was noted intraoperatively in 12 cases (7, 100-μm group; 5, 120-μm group; P = .577). No postoperative complications were observed.

CONCLUSIONS

Our study did not find any differences in the visual and refractive outcomes between femtosecond-assisted sub-Bowman keratomileusis and LASIK. Both surgeries resulted in quick visual recovery as early as 1 week postoperatively.