Comparison of Wavelight Allegretto Eye-Q and Schwind Amaris 750S excimer laser in treatment of high astigmatism

First European results of a new refractive lenticular extraction procedure-SmartSight by SCHWIND eye-tech-solutions

BACKGROUND

To evaluate vision 3 months after SmartSight lenticule extraction treatments.

DESIGN

Case series.

METHODS

This case series of patients were treated at Specialty Eye Hospital Svjetlost in Zagreb, Croatia. Sixty eyes of 31 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 33 ± 6 years (range 23-45 years) at the time of treatment with a mean spherical equivalent refraction of -5.10 ± 1.35 D and mean astigmatism of 0.46 ± 0.36 D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Ocular and corneal wavefront aberrations have been postoperatively compared to the preoperative baseline values. Changes in ocular wavefront refraction, as well as changes in keratometric readings are reported.

RESULTS

At 3 months post-operatively, mean UDVA was 20/20 ± 2. Spherical equivalent showed a low myopic residual refraction of -0.37 ± 0.58 D with refractive astigmatism of 0.46 ± 0.26 D postoperatively. There was a slight improvement of 0.1 Snellen lines at 3-months follow-up. Compared to the preoperative status, ocular aberrations (at 6 mm diameter) did not change at 3 months follow-up; whereas corneal aberrations increased (+0.22 ± 0.21 µm for coma; +0.17 ± 0.19 µm for spherical aberration; and +0.32 ± 0.26 µm for HOA-RMS). The same correction was determined using changes in ocular wavefront refraction, as well as changes in keratometric readings.

CONCLUSION

Lenticule extraction after SmartSight is safe and efficacious in the first 3 months postoperatively. The post-operative outcomes indicate improvements in vision.

Twelve-month outcomes of a new refractive lenticular extraction procedure

BACKGROUND

To evaluate the 12-month refractive and visual outcomes of Small Incision Guided Human-cornea Treatment (SmartSight®, SCHWIND eye-tech-solutions, Kleinostheim, Germany) in the treatment of myopia corrections with low to moderate astigmatism with the use of a new femtosecond laser system.

METHODS

221 eyes of 114 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 28±6 years at the time of treatment with a mean spherical equivalent refraction of -6.26±2.17D and mean astigmatism of 0.92±0.68D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Refractive changes have been determined in terms of changes in refraction, as well as changes in keratometric readings. The changes in central epithelial thickness have been determined.

RESULTS

At twelve months post-operatively, mean UDVA was 20/21±2. Spherical equivalent showed a residual refraction of +0.48±0.31D with refractive astigmatism of 0.13±0.18D postoperatively. There was a slight decrease of -0.1 Snellen lines at 12-months follow-up. The same correction was determined using changes in refraction, as well as changes in keratometric readings. The central epithelial thickness increased by +3±2µm. Spherical equivalent correction within ±0.50D was achieved in 199 eyes (90%), and cylindrical correction in 221 (100%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 213 eyes (96%), and postoperative uncorrected (UDVA) was 20/20 or better in 205 eyes (93%). No eye had lost two or more Snellen lines of CDVA.

CONCLUSIONS

Myopic astigmatism correction with SmartSight provided good results for efficacy, safety, predictability, and visual outcomes at the twelve months of follow up. The central epithelial thickness barely increased by 3±2µm.

Refractive Outcomes After LASIK for the Treatment of Mixed Astigmatism with the Allegretto WaveLight EX500

INTRODUCTION

Treatment of mixed astigmatism with laser in situ keratomileusis (LASIK) is complex as the correction requires flattening the cornea in one meridian while steepening the cornea in the other meridian. The bitoric technique has become the most popular approach and has been tested across a variety of platforms. This study is the first to evaluate the results of mixed astigmatism treatment using the Allegretto WaveLight^® EX500.

METHODS

This study was a single-center, retrospective, noncomparative analysis of 400 eyes that underwent LASIK to correct for mixed astigmatism utilizing the EX500 excimer laser. Data on uncorrected distance visual acuity, corrected distance visual acuity, and spherical equivalent was analyzed at consecutive intervals (1, 3, 6, 9, and 12 months). Refractive measurements were used to perform a vector analysis.

RESULTS

Three and 12 months postoperatively, 71% and 74% of eyes had an uncorrected distance visual acuity (UDVA) of 20/20 or better and 99% and 100% of eyes had a UDVA of 20/40 or better, respectively. The postoperative UDVA was within one line of the corrected distance visual acuity (CDVA) in 88% and 93% of eyes at 3 and 12 months, respectively. At 3 months, 78% of eyes achieved refractive astigmatism no greater than 0.50 diopters and at 12 months, 80% achieved this. The mean spherical equivalent refraction was - 0.36 ± 0.57 D at 12 months after surgery. At the 12-month follow-up, the mean refractive cylinder was reduced by 87%, from - 2.79 to - 0.37 diopters. On vector analysis, 99% of eyes had an angle of error within ± 15° from the intended target at 3 and 12 months.

CONCLUSION

Treatment of mixed astigmatism using the Allegretto WaveLight^® EX500 laser exceeded the industry standards of safety, efficacy, stability, and accuracy.

Thermographic Behavior of the Cornea During Treatment With Two Excimer Laser Platforms

Purpose

To investigate the temperature of the cornea during treatment with the excimer laser using two platforms, Nidek EC-5000 and Schwind Amaris 750S.

Methods

A prospective case series study was conducted in a reference center in Mexico City including patients aged 18 years or older who had any type of ametropia and underwent excimer laser refractive surgery. The patients had measurements of corneal temperature with an infrared camera before, during, and after ablation treatment. Results of prior corneal surface temperature, temperatures during excimer laser surgery, and delta temperature for each platform were analyzed and compared.

Results

A total of 107 eyes were analyzed. Mean baseline temperature was 32.7 ± 1.03°C for the Nidek group and 31.5 ± 1.4°C for the Amaris group. Mean maximum temperature was 39.94 ± 1.3°C for the Nidek group and 35.6 ± 1.5 °C for the Amaris group. Delta temperature was higher in the Nidek group than in the Amaris group. There were statistically significant associations between treated micrometers, treated diopters, and time in the Nidek group and no such associations in the Amaris group.

Conclusions

The different excimer laser devices used and the variety in the optical design, together with different software ablation algorithms, resulted in different levels of thermal loading; peak temperature rose in all measurements. Eyes treated with Nidek reached temperatures that doubled those found with Amaris.

Translational Relevance

The correlation between Delta of temperature with defocus, depth, and treatment time is different regarding excimer laser generation.

Comparison of Corneal Wavefront-optimized and Wavefront-guided Alcohol-assisted Photorefractive Keratectomy Using Schwind Amaris 750S Laser for Myopia

Purpose

To compare the visual outcomes and corneal aberrations between wavefront-optimized (WFO) and corneal wavefront-guided (WFG) photorefractive keratectomy (PRK) in low to moderate myopia.

Methods

Twenty-seven eyes treated with WFO and 29 eyes treated with WFG PRK using a Schwind Amaris 750S Excimer laser were included after 6 months of postoperative follow-up. Uncorrected distance visual acuity, corrected distance visual acuity, refractive errors, corneal higher-order aberrations (HOA) and corneal thickness obtained using a Scheimpflug system, and central ablation depth and volume were evaluated during the preoperative period and again at the postoperative 6-month visits.

Results

Postoperatively, uncorrected distance visual acuity, corrected distance visual acuity, manifest spherical equivalent, and refractive astigmatism were improved in both groups, and there was no statistically significant difference between the two groups. There was no significant difference in safety, efficacy, or predictability of the refractive outcome. Postoperative total corneal HOA root mean square (RMS), coma RMS, and spherical aberration were significantly increased in both groups. Among these, only spherical aberration showed a significant difference between the two groups, with greater increase in the WFO group at 6 months postoperatively. The changes in corneal HOA RMS and spherical aberration were smaller in the WFG group, and this benefit was marked in eyes with high HOA RMS (≥0.4 µm) and spherical aberration (≥0.2 µm). Even though ablation volume in the WFG group was much larger than that of the WFO group, there was no significant difference in postoperative central and peripheral corneal thickness between the two groups.

Conclusions

Both WFO and WFG PRK using a Schwind Amaris 750S laser for low to moderate myopia were safe and effective at improving visual and refractive outcomes. However, WFG PRK induced fewer spherical aberrations than WFO PRK and may be more advantageous for eyes with high HOA root mean square or spherical aberration.

One-Year Visual and Refractive Outcomes following LASIK for Myopia and Myopic Astigmatism with MEL 90 versus Schwind Amaris 750S Excimer Laser: A Comparative Study

Purpose

To compare clinical outcomes following LASIK for myopia performed with MEL 90 vs. Schwind Amaris 750S excimer laser.

Methods

Data were collected retrospectively for patients who underwent Femto-LASIK, using the MEL 90 and Schwind Amaris 750S excimer laser for correction of myopia and myopic astigmatism within the range of -1.00 to -10.00 D SE from January 2013 till June 2018. Outcomes were analysed at 12 months for safety, efficacy, enhancement rate, and long-term complications.

Results

A total of 328 eyes of 328 patients were analysed. One hundred and sixty-three eyes were treated with Schwind Amaris and the remaining 165 eyes with the MEL 90 laser. Twelve months postoperatively, the mean UDVA, CDVA, residual SE, and cylinder in the Amaris group were -0.10 ± 0.09 logMAR, -0.14 ± 0.06 logMAR, -0.21 ± 0.22 D, -0.13 ± 0.18 D versus -0.05 ± 0.07 logMAR, -0.09 ± 0.08 logMAR, -0.23 ± 0.23 D, and -0.14 ± 0.21 D for the MEL 90 group (p values >0.05). For the Amaris group, safety and efficacy indices were 1.12 and 1.02, whereas for the MEL 90 group, these indices were 1.08 and 1.00, respectively. No eye in either group had any postop flap-related complications, infectious keratitis, diffuse lamellar keratitis, or keratectasia. Two eyes in the Amaris and 4 eyes in MEL 90 group required enhancement for the progression of myopia.

Conclusion

At 12 months, both Schwind Amaris 750S and MEL 90 lasers demonstrated comparable clinical outcomes for myopic LASIK in a single surgeon setting.

Photorefractive keratectomy (PRK) Prediction, Examination, tReatment, Follow-up, Evaluation, Chronic Treatment (PERFECT) protocol - A new algorithmic approach for managing post PRK haze

Purpose

The aim of this study was to discuss the possible risk factors predisposing to post photorefractive keratectomy (PRK) haze formation and develop and validate a risk scoring system, so that this could be applied to our clinical practice as an algorithmic approach.

Methods

Study was divided into 2 arms, in the retrospective arm we looked at 238 eyes of patients undergoing PRK where certain presumed risk factors from literature and clinical experience were identified and statistical significance of association was studied in the development of corneal haze. The risk scoring system was applied to the 450 eyes in the prospective arm for validation. This was then used to formulate an algorithmic approach to manage post-PRK haze.

Results

22 out of 238 eyes in the retrospective arm developed haze where risk factors such as contact lens intolerance, altered tear film break up time, meibomian gland drop out and vitamin d levels were significantly associated with post-PRK haze (p < 0.05) and these factors were identified in the prospective arm. Treatment of these modifiable factors led to a significant reduction in post-PRK haze.

Conclusion

Thus identifying and treating risk factors of haze in patients undergoing PRK could improve surgical outcomes and patient satisfaction.

Combined Phototherapeutic Keratectomy and Peripheral Anterior Stromal Puncture for the Treatment of Recurrent Corneal Erosion Syndrome

PURPOSE

To investigate the efficacy of the combined phototherapeutic keratectomy (PTK) and peripheral anterior stromal puncture (ASP) compared with that of PTK alone in patients with recurrent corneal erosion syndrome (RCES).

METHODS

The medical records of 25 patients (25 eyes) who underwent combined treatment of PTK and peripheral ASP for RCES from March 2016 to May 2017 were retrospectively reviewed. Twenty-three patients (23 eyes) treated with PTK alone from March 2015 to February 2016 served as a control group. All surgeries were performed by a single surgeon. This retrospective clinical study comprised 48 patients (48 eyes) who were followed up for more than 18 months. Clinical records of age, sex, laterality, etiology of RCES, and history of recurrence after treatment were evaluated.

RESULTS

Twenty-five eyes were treated with combined PTK and ASP, and 23 eyes were treated with PTK only. The mean follow-up period was 19.63 ± 2.97 and 19.75 ± 6.83 months, respectively. There were no differences in baseline parameters between the groups. In the combined treatment group, one patient experienced recurrence 6 months after the surgery. In the single treatment group, five patients showed recurrence at 4, 7, 8, 11, and 13 months after the surgery, respectively. Compared to the single treatment group, the combined treatment group showed significantly lower recurrence rate (p < 0.05). All recurred patients required no additional treatment except temporary therapeutic contact lenses and topical lubricants.

CONCLUSIONS

Our findings suggest that combined treatment of PTK and peripheral ASP is effective in alleviation of symptoms and prevention of recurrence in refractory RCES compared with treatment using PTK alone.

Outcomes for Mixed Cylinder LASIK With the MEL 90® Excimer Laser

PURPOSE

To report the outcomes of LASIK for mixed cylinder using the Triple-A ablation profile with the MEL 90 excimer laser (Carl Zeiss Meditec, Jena, Germany).

METHODS

This was a retrospective analysis of all eyes treated by LASIK for mixed cylinder using the Triple-A ablation profile with the MEL 90 laser between July 2013 and October 2016. Patients were observed for 1 year after surgery. Standard outcomes analysis and vector analysis by the Alpins method were performed.

RESULTS

The database review identified 105 eyes (82 patients) treated by LASIK for mixed cylinder using the MEL 90 laser. Mean age was 40 ± 11 years (range: 18 to 65 years). Mean attempted spherical equivalent was +0.30 ± 0.90 diopters (D) (range: -2.30 to +1.75 D). Mean cylinder was -2.93 ± 1.47 D (range: -0.75 to -7.00 D). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 81% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 69% and 20/25 or better in 86% of eyes. Mean postoperative spherical equivalent relative to the intended target was -0.21 ± 0.38 D (range: -1.25 to +1.13 D), with 83% within ±0.50 D. Mean postoperative cylinder was -0.57 ± 0.41 D (range: 0.00 to -1.75 D). Geometric mean was 1.12 for the correction index and 0.25 for the index of success. For angle of error, the arithmetic mean was -0.6° ± 4.2° (range: -13.5° to 9.5°) and the absolute mean was 2.9° ± 3.0° (range: 0.0° to 13.5°). There was loss of one line of CDVA in 3% of eyes and no eyes lost two or more lines CDVA. There was a small increase in contrast sensitivity after surgery at 3, 6, 12, and 18 cycles per degree (P < .05).

CONCLUSIONS

One-year outcomes of LASIK using the MEL 90 laser for mixed cylinder up to -7.00 D demonstrated excellent efficacy, safety, and predictability. Vector analysis found a 12% overcorrection in magnitude of refractive cylinder. Given the high accuracy for angle of error, a nomogram could be applied to reduce the over-correction and further improve the uncorrected distance visual acuity outcomes. [J Refract Surg. 2018;34(10):672-680.].

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 and Higher Order Aberrations Following LASIK on Eyes with Low Myopia and Astigmatism

Background:

Laser-Assisted in situ Keratomileusis (LASIK) can induce corneal aberrations that can impact vision and patient satisfaction. Recent developments in laser technologies have helped minimise these aberrations.

Objective:

To assess the quality of vision and change in Higher-Order Aberrations (HOAs) following wavefront-optimized LASIK in low-myopic astigmatic patients.

Methods:

LASIK was performed on a total of 76 eyes in patients with myopia <4.0 D and cylinder <2.0 D using the WaveLight® EX500 excimer and FS200 femtosecond laser platform. Visual acuity, contrast sensitivity and HOAs were measured at 1 and 3 months postoperatively and compared to preoperative values. Subjective quality of vision was assessed pre- and postoperatively using a VF14 questionnaire.

Results:

Mean postoperative Spherical Equivalent (SE) was -0.09 ± 0.26 µm with 95% of patients within ± 0.5 D of attempted SE. Postoperative uncorrected distance visual acuity was 20/20 or better for 96% of patients. Contrast sensitivity increased against horizontal and vertical gratings at all spatial frequencies except for vertical gratings at 18 cycles/degree. Spherical aberration and total HOA increased by 0.085 µm and 0.13 µm respectively. The mean VF14 score increased from 89.2 ± 16.7% to 99 ± 1.4% postoperatively.

Conclusion:

LASIK performed using the WaveLight® EX500 excimer and WaveLight® FS200 laser platform provided improved contrast sensitivity and visual acuity with minimal introduction of HOAs, making it a suitable platform for low myopic astigmatic patients.

Comparative analysis of the efficacy of astigmatic correction after wavefront-guided and wavefront-optimized LASIK in low and moderate myopic eyes

AIM

To evaluate and compare the efficacy of the astigmatic correction achieved with laser in situ keratomileusis (LASIK) in eyes with myopic astigmatism using wavefront-guided (WFG) and wavefront-optimized (WFO) ablation profiles.

METHODS

Prospective study included 221 eyes undergoing LASIK: 99 and 122 eyes with low and moderate myopic astigmatism (low and moderate myopia groups). Two subgroups were differentiated in each group according to the ablation profile: WFG subgroup, 109 eyes (45/64, low/moderate myopia groups) treated using the Advanced CustomVue platform (Abbott Medical Optics Inc.), and WFO subgroup, 112 eyes (54/58, low/moderate myopia groups) treated using the EX-500 platform (Alcon). Clinical outcomes were evaluated during a 6-month follow-up, including a vector analysis of astigmatic changes.

RESULTS

Significantly better postoperative uncorrected visual acuity and efficacy index was found in the WFG subgroups of each group (P≤0.041). Postoperative spherical equivalent and cylinder were significantly higher in WFO subgroups (P≤0.003). In moderate myopia group, a higher percentage of eyes with a postoperative cylinder ≤0.25 D was found in the WFG subgroup (90.6% vs 65.5%, P=0.002). In low and moderate myopia groups, the difference vector was significantly higher in the WFO subgroup compared to WFG (P<0.001). In moderate myopia group, the magnitude (P=0.008) and angle of error (P<0.001) were also significantly higher in the WFO subgroup. Significantly less induction of high order aberrations were found with WFG treatments in both low and moderate myopia groups (P≤0.006).

CONCLUSION

A more efficacious correction of myopic astigmatism providing a better visual outcome is achieved with WFG LASIK compared to WFO LASIK.

Comparison of femtosecond and excimer laser platforms available for corneal refractive surgery

PURPOSE OF REVIEW

The evolution of laser technology has left today's refractive surgeon with a choice between multiple laser platforms. The purpose of this review is to compare currently available femtosecond and excimer laser platforms, providing a summary of current evidence.

RECENT FINDINGS

Femtosecond lasers create LASIK flaps with better accuracy, uniformity, and predictability than mechanical microkeratomes. Newer higher-frequency femtosecond platforms elicit less inflammation, producing better visual outcomes. SMILE achieved similar safety, efficacy, and predictability as LASIK with greater preservation of corneal nerves and biomechanical strength. The emergence of wavefront technology has resulted in improved excimer laser treatments. Comparisons of wavefront-guided and wavefront-optimized treatments suggest that there is an advantage to using wavefront-guided platforms in terms of visual acuity and quality of vision. Topography-guided ablations are another well tolerated and effective option, especially in eyes with highly irregular corneas.

SUMMARY

Advances in femtosecond and excimer laser technology have not only improved the safety and efficacy of refractive procedures, but have also led to the development of promising new treatment modalities, such as SMILE and the use of wavefront-guided and topography-guided ablation. Future studies and continued technological progress will help to better define the optimal use of these treatment platforms.

Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) for Myopia: A Systematic Review and Meta-Analysis

Purpose

The goal of this study was to compare small incision lenticule extraction (SMILE) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for treating myopia.

Methods

The CENTRAL, EMBASE, PubMed databases and a Chinese database (SinoMed) were searched in May of 2016. Twelve studies with 1,076 eyes, which included three randomized controlled trials (RCTs) and nine cohorts, met our inclusion criteria. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group framework. Data were extracted and analysed at three to six months postoperatively. Primary outcome measures included a loss of one or more lines of best spectacle corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA) of 20/20 or better, mean logMAR UCVA, postoperative mean spherical equivalent (SE) and postoperative refraction within ±1.0 D of the target refraction. Secondary outcome measures included ocular surface disease index (OSDI), tear breakup time (TBUT) and Schirmer’s 1 test (S1T) as dry eye parameters, along with corneal sensitivity.

Results

The overall quality of evidence was considered to be low to very low. Pooled results revealed no significant differences between the two groups with regard to a loss of one or more lines in the BSCVA (OR 1.71; 95% CI: 0.81, 3.63; P = 0.16), UCVA of 20/20 or better (OR 0.71; 95% CI: 0.44, 1.15; P = 0.16), logMAR UCVA (MD 0.00; 95% CI: -0.03, 0.04; P = 0.87), postoperative refractive SE (MD -0.00; 95% CI: -0.05, 0.05; P = 0.97) or postoperative refraction within ±1.0 D of the target refraction (OR 0.78; 95% CI: 0.22, 2.77; P = 0.70) within six months postoperatively. The pooled analysis also indicated that the FS-LASIK group suffered more severely from dry eye symptoms (OSDI; MD -6.68; 95% CI: -11.76, -2.00; P = 0.006) and lower corneal sensitivity (MD 12.40; 95% CI: 10.23, 14.56; P < 0.00001) at six months postoperatively.

Conclusions

In conclusion, both FS-LASIK and SMILE are safe, effective and predictable surgical options for treating myopia. However, dry eye symptoms and loss of corneal sensitivity may occur less frequently after SMILE than after FS-LASIK.

Topography-Guided Transepithelial Surface Ablation in the Treatment of Moderate to High Astigmatism

PURPOSE

To analyze the outcomes of treatment of astigmatism of 2.00 diopters (D) or greater with topography-guided transepithelial surface ablation.

METHODS

Retrospective analysis of a series of 206 eyes divided into two groups: myopic astigmatism (153 eyes) and mixed astigmatism (53 eyes). All cases were treated with topography-guided transepithelial surface ablation. Efficacy, safety, and predictability were evaluated, and vector analysis of cylindrical correction was performed.

RESULTS

The median preoperative spherical equivalent was -2.63 and -0.63 D for the myopic and mixed astigmatism groups, respectively, with median cylinder of -2.50 D. Postoperative uncorrected distance visual acuity was 20/20 or better in 92% and 83% of eyes in the myopic and mixed astigmatism groups, respectively; the corresponding efficacy indices were 1.00 and 0.96 and residual astigmatism of 0.50 D or less was present in 82.4% and 56.7% of eyes in the myopic and mixed astigmatism groups, respectively. The arithmetic mean magnitude of the difference vector was 0.38 (myopic) and 0.65 (mixed) D. Difference vector magnitude was positively correlated with the magnitude of target induced astigmatism in both groups. The geometric mean coefficient of adjustment index was 1.04 and 1.19, representing undercorrection of 4% and 19% in the myopic and mixed astigmatism groups, respectively.

CONCLUSIONS

Topography-guided transepithelial ablation is a safe, effective, and predictable treatment for moderate to high astigmatism. [J Refract Surg. 2016;32(6):418-425.].

Vector analysis of astigmatism before and after LASIK: a comparison of two different platforms for treatment of high astigmatism

PURPOSE

To compare the outcomes of astigmatic laser in-situ keratomileusis (LASIK) procedures between two different platforms using J0 and J45 vector analysis.

METHODS

Patients were divided into four groups, depending on the type of astigmatism and laser platform on which they were treated. Astigmatism was between 2 and 7 diopters (D). One hundred and thirty-five patients with myopic astigmatism (246 eyes) and 102 patients with mixed astigmatism (172 eyes) underwent unremarkable LASIK correction on Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S laser platform. The preoperative and postoperative sphere, negative cylinder [C] and axis (ø) of manifest refractions were subjected to vector analysis by calculations of the standard J0 (cos [4π(ø-90)/360]xC/2) and J45 (sin[4π(ø-90)/360]xC/2).

RESULTS

Reporting the key results, we found J0 significantly reduced after LASIK in both groups (p < 0.001) but not J45. There was no significant association between individual pairs of pre and postoperative J0 & J45 values. There was no significant difference between the outcomes of the two platforms.

CONCLUSIONS

Wavelight Allegretto 400Hz and Schwind Amaris 750S showed excellent results for treating patients with astigmatism, regardless whether it is mixed or myopic astigmatism. The J45 did not reduce significantly possibly because of the low number of eyes with oblique astigmatism. There was no genuine difference post-operatively between groups treated on two different laser platforms according to the vector analyses.

Outcomes for Myopic LASIK With the MEL 90 excimer laser

PURPOSE

To evaluate the visual outcomes of myopic LASIK performed with the MEL 90 excimer laser (Carl Zeiss Meditec AG, Jena, Germany) using the Triple-A profile with a 500-Hz pulse rate.

METHODS

Retrospective analysis of the first 286 myopic LASIK procedures (147 patients) by two experienced surgeons in which the VisuMax femtosecond laser and MEL 90 excimer laser (Carl Zeiss Meditec) were used following a standardized surgical technique. Inclusion criteria were preoperative spherical equivalent refraction (SEQ) up to -10.38 diopters (D), cylinder up to 5.00 D, and corrected distance visual acuity (CDVA) of 20/25 or better. No nomogram adjustments were made. Patients were observed for 3 months. Flap thickness was between 80 and 110 µm and optical zone was between 6 and 7 mm. Standard outcomes analysis was performed.

RESULTS

Preoperatively, mean SEQ was -3.83 ± 1.83 D (range: -0.13 to -10.38 D) and mean cylinder was -0.94 ± 0.86 D (range: 0.00 to -5.00 D). Mean age was 36.4 years (range: 18.2 to 74.1 years) with 50% female patients. Of this population, 138 eyes were treated by one surgeon and 148 eyes by another. The mean predictability of SEQ was -0.13 ± 0.34 D (range: -1.00 to +1.00 D). Postoperative SEQ was ± 0.50 D in 88% and ± 1.00 D in 100% of eyes. Preoperative CDVA was 20/20 or better in 97% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 92% and 20/25 or better in 99% of eyes. One line of CDVA was lost in 6% of eyes and no eyes lost two or more lines. There was statistically significant improvement in mesopic contrast sensitivity (CSV-1000) at 3 (P = .021), 6, 12, and 18 (all P ≤.001) cycles per degree.

CONCLUSIONS

The MEL 90 excimer laser using the Triple-A ablation profile with a 500-Hz pulse rate was found to achieve a small but real increase in contrast sensitivity and high efficacy for myopia up to -10.00 D and cylinder up to 5.00 D without the need for a nomogram adjustment.