Femtosecond lenticule extraction for correction of myopia: a 6 month follow-up study

Features of Femtosecond Correction of High Myopia through Small Access

Aim. To modify the calculated parameters of the lenticle extraction refractive surgery through a small access (SMILE), evaluate its safety and clinical efficacy in correcting high myopia.

Materials and methods. 34 patients (68 eyes) underwent surgery by a modified SMILE technology under local anesthesia. In all cases, the patients had a high degree of myopia, in 37 % in combination with astigmatism.

Uncorrected visual acuity before surgery averaged 0.05 ± 0.11, best corrected visual acuity of 0.94 ± 0.1, the pre-operative spherical refraction component was –7.23 ± 0.75, the cylindrical component was –0.48 ± 0.59.

During the operation, to obtain the maximum possible refraction result using the proposed method, the standard operation parameters were changed: the corneal flap thickness was reduced to 100 μm, the neural optical layer by 5 μm, the diameter of the optical zone depended on the residual cornea thickness, which should exceed 280–290 μm. Corneal access was increased by 15–20 degrees.

Results. The next day after surgery, monocular uncorrected visual acuity in distance in 73 % of patients was 0.8 or higher, and in 41 % of cases it was equal to or exceeded 1.0. The spherical equivalent on the first day after surgery had a slight hypermetropic shift, which was completely leveled by the year of follow-up. During the surgical intervention and in the postoperative period, no complications were noted.

Conclusion. Using the proposed algorithm for calculating the refractive effect of the operation SMILE with a high degree of myopia allows obtaining a high refractive effect and avoiding possible complications.

Predictive Factors for Successful High Myopia Treatment Using High-Frequency Laser-In-Situ Keratomileusis

Aim

To evaluate the predictive factors of LASIK procedure for high myopia with or without astigmatism using a combination of high-frequency femtosecond-assisted LASIK followed by an excimer laser.

Methods

This study was a retrospective interventional case series study to evaluate myopic eyes undergoing high platform LASIK with FEMTO LDV Z2 intervention, followed by WaveLight®EX500 excimer laser machine. Subjects were divided into 2 groups: high myopia (SE of -6.01 to -9.00 D) and very high myopia (SE of -9.01 D or higher). Myopic eyes (Spherical Equivalent/SE) less than -13 D were included in this study. Visual Acuity (VA) was evaluated 1 day and 60 days after the procedure. Predictive factors, such as age, degree of sphere, degree of astigmatism, keratometric reading and axial length were analyzed to detect any influences affecting the final VA results.

Results

A total of 316 myopia eyes underwent intervention, mean age: 25.3±3.8 years. Target treatment was achieved in 96.1% of patients with high myopia and 69.9% of patients with very high myopia. High degree of sphere and astigmatism constitutes an important factor influencing final VA.

Conclusion

Modern machines provide a more promising efficacy and success of LASIK procedure in high myopia: important predictive factors were a high degree of sphere and astigmatism for achieving the optimal final outcome.

Visual outcomes after balanced salt solution infiltration during lenticule separation in small-incision lenticule extraction for myopic astigmatism

To evaluate the refractive outcomes of balanced salt solution infiltration during small-incision lenticule extraction (SMILE).This randomized prospective study enrolled 52 patients (104 eyes) with myopic astigmatism. Patients underwent SMILE to correct the myopic astigmatism in Daping Hospital of the Third Military Medical University between January and July 2013. One eye of each patient received traditional SMILE (control group) and the other received a modified SMILE procedure (liquid infiltration group). The corrected distance visual acuity (CDVA), postoperative uncorrected distance visual acuity (UDVA), refraction, wavefront aberration, intraocular pressure (IOP), modulation transfer function (MTF) cut-off frequency, and objective scattering index (OSI) were evaluated.UDVA in the liquid infiltration group was significantly higher than that in the control group at 1 day postoperatively, but not at 1 month after surgery. Moreover, OSI and MTF cut-off frequency in the liquid infiltration group were higher than those in the control group at early follow-up. However, no significant intergroup difference was observed in the OSI and MTF cut-off frequency at 3 months after surgery. In addition, the predictability was better in the liquid infiltration group than in the control group. The changes of horizontal coma in the liquid infiltration group were lesser than those in the control group. However, no intergroup difference was observed in the reduction of IOP at 1 month after surgery.The modified SMILE procedure results in better visual outcomes than did the traditional SMILE procedure when used for treating myopic astigmatism.

Refractive lenticule extraction (ReLEx) through a small incision (SMILE) for correction of myopia and myopic astigmatism: current perspectives

Small-incision lenticule extraction (SMILE) is an alternative to laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for the correction of myopia and myopic astigmatism. SMILE can be performed for the treatment of myopia ≤−12 D and astigmatism ≤5 D. The technology is currently only available in the VisuMax femtosecond laser platform. It offers several advantages over LASIK and PRK; however, hyperopia treatment, topography-guided treatment, and cyclotorsion control are not available in the current platform. The working principles, potential advantages, and disadvantages are discussed in this review.

Efficacy, safety, predictability, aberrations and corneal biomechnical parameters after SMILE and FLEx: Meta-analysis

AIM

To identify possible differences of efficacy, safety, predictability, higher-order aberrations and corneal biomechnical parameters after small-incision lenticule extraction (SMILE) and femtosecond lenticule extraction (FLEx).

METHODS

A systematic literature retrieval was conducted in Medline, Embase and the Cochrane Library, up to October, 2015. The included studies were subject to a Meta-analysis. Comparison between SMILE and FLEx was measured as pooled odds ratio (OR) or weighted mean differences (WMD). Of 95% confidence intervals (CI) were used to analyze data.

RESULTS

A total of seven studies were included. Firstly, there were no differences in uncorrected distance visual acuity (UDVA) 20/20 or better (OR, 1.37; 95% CI, 0.69 to 2.69; P=0.37) and logMAR UDVA (WMD, -0.02; 95% CI, -0.05 to 0.01; P=0.17) after SMILE versus FLEx. We found no differences in corrected distance visual acuity (CDVA) unchanged (OR, 0.98; 95% CI, 0.46 to 2.11; P=0.97) and logMAR CDVA (WMD, -0.00; 95% CI, -0.01 to 0.01; P=0.90) either. Secondly, we found no differences in refraction within ±1.00 D (OR, 0.98; 95% CI, 0.13 to 7.28; P=0.99) and ±0.50 D (OR, 1.62; 95% CI, 0.62 to 4.28; P=0.33) of target postoperatively. Thirdly, for higher-order aberrations, we found no differences in the total higher-order aberrations (WMD, -0.04; 95% CI, -0.09 to 0.01; P=0.14), coma (WMD, -0.04; 95% CI, -0.09 to 0.01; P=0.11), spherical (WMD, 0.01; 95% CI, -0.02 to 0.03; P=0.60) and trefoil (WMD, -0.00; 95% CI, -0.04 to 0.03; P=0.76). Furthermore, for corneal biomechanical parameters, we also found no differences (WMD, 0.08; 95% CI, -0.17 to 0.33; P=0.54) after SMILE versus FLEx.

CONCLUSION

There are no statistically differences in efficacy, safety, predictability, higher-order aberrations and corneal biomechnical parameters postoperative between SMILE and FLEx.

Efficacy, predictability, and safety of small incision lenticule extraction: 6-months prospective cohort study

Background

To report our experience with small incision lenticule extraction ("SMILE") for myopia treatment.

Methods

In this prospective clinical study, we evaluated 447 eyes from 224 patients with myopia, with and without astigmatism. We followed the patients for 6 months after SMILE.

Results

The mean (±standard deviation, SD) spherical equivalent was -6.75 ± 1.65 diopters (D) preoperatively and -0.21 ± 0.37 D at 6 months postoperatively. Our data showed that 97.9% of eyes were within ±1.0 D and 86.1% were within ±0.5 D of the intended correction. Furthermore, 79.8% had an uncorrected distance visual acuity (UDVA) of 0 logMAR or less (20/20 or better in the Snellen equivalent) 6 months after surgery. Additionally, 48.5% remained unchanged, 41% gained one line of corrected distance visual acuity (CDVA), 7.2% gained two lines of CDVA, 3.3% lost one line of CDVA, and 0.3% lost two or more lines of CDVA. Age was the only predictor for worsening UDVA at 6 months postoperatively in linear regression analyses (0.07 decrease logMAR per increased 10 years of age; P < 0.05). No predictor showed an association with error in spherical equivalent refraction at 6 months postoperatively.

Conclusions

SMILE is an effective and safe refractive surgery. Age was the only predictor that influenced visual outcome, but its effect appeared clinically insignificant. Faster visual recovery is also expected with improved surgical technique.

[Innovations in refractive laser surgery 2014]

BACKGROUND

Within less than 30 years refractive laser surgery has been developed from an experimental technique to one of the most frequently applied procedures in ophthalmology worldwide.

RESULTS

Regarding the success rate of refractive results, myopia correction has reached a level (95% within ± 0.5 D) that is comparable to manifest refraction so that there is not much room for improvement. The most recently developed technique is femtosecond laser lenticule extraction which was introduced in 2007 in Germany. Early clinical results were very promising but the awaited bilateral comparative studies are still lacking. Although new laser types that will be able to provide improved profiles are on the horizon, the problem of reoperations has not yet been solved. Topography-guided ablation is notoriously plagued by undercorrection so that topography-guided treatment is planned as a two step-procedure. The reason for the undercorrection is the leveling effect of the epithelium.

PERSPECTIVES

The evolution of refractive surgery has slowed down during the last years, however, some important innovations are at the advent.