Bitoric laser in situ keratomileusis for astigmatism

Feasibility study of treatment of mixed astigmatism with small-incision lenticule extraction (SMILE) by using research software

PURPOSE

To report the preliminary experience and initial clinical results following SMILE for the treatment of mixed astigmatism.

METHODS

Thirteen eyes of nine patients with a mean age of 27 ± 4.36 years were included in the series. In 8/13 eyes, myopic SMILE license and in 4/13 eyes, hyperopic SMILE license (available as part of an open/research software) was used for the treatment. The mean follow-up was 9.5 ± 8.7 (0.5-24) months, and the median follow-up was 6 months.

SETTING

Nethradhama Superspeciality Eye Hospital, Bangalore, India.

DESIGN

Exploratory study.

RESULTS

The mean preoperative sphere, cylinder, and spherical equivalent (SE) were 1.44 ± 1.63, -2.70 ± 2.30, and -0.24 ± 1.14 D, which changed to -0.03 ± 0.30, -0.28 ± 0.48, and -0.18 ± 0.49 D, respectively, 6 months postoperatively. Furthermore, 85% (11/13) eyes were within ± 0.50 D, 92% (12/13) eyes were within ± 1.00 D, while all eyes were within ± 1.50 D of SE correction. All eyes were within ± 1.00 D of cylinder correction. In addition, 92% (12/13) eyes had UDVA better than 20/32, with 54% (7/13) eyes having UDVA 20/20 or better. Safety and efficacy indices were 1.08 and 0.92, respectively. No eyes lost more than 1 line of CDVA. The mean corneal higher order aberrations (HOA) increased from 0.111 ± 0.048 to 0.209 ± 0.056 (P < 0.001). The mean objective scatter index (OSI) did not show a significant change (pre = 0.71 ± 0.69, 6 months = 0.89 ± 0.20; P = 0.35).

CONCLUSION

Early experience showed that SMILE was feasible for the management of eyes with mixed astigmatism, without any intraoperative complications, unique to the procedure.

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.

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.].

Acute effect of cigarette smoking on pupil size and ocular aberrations: a pre- and postsmoking study

Aim. To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations. Methods. Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately after smoking. All volunteers were asked to smoke a single cigarette containing 1.0 mg nicotine. Pupil sizes and total ocular aberrations were assessed by optical path difference scanning system (OPD-Scan II ARK-10000, NIDEK). Only the right eyes were considered for statistical analysis. The changes of pupil size and total ocular aberrations after smoking were tested for significance by Wilcoxon signed ranks test. Results. Mean photopic pupil size decreased from 3.52 ± 0.73 mm to 3.29 ± 0.58 mm (P = 0.001) after smoking. Mean mesopic pupil size was also decreased from 6.42 ± 0.75 mm to 6.14 ± 0.75 mm after smoking (P = 0.001). There was a decrease in all the measured components of aberrations (total wavefront aberration, higher-order aberration, total coma, total trefoil, total tetrafoil, total spherical aberration and total higher-order aberration) after smoking; however the differences were insignificant for all (P > 0.05). Conclusion. Our results indicate that pupil constricts after smoking. On the other hand, smoking does not alter ocular aberrations.

Ocular residual astigmatism's effect on high myopic astigmatism LASIK surgery

PURPOSE

To analyze the effect of ocular residual astigmatism (ORA) on the effectiveness of LASIK for treating high myopic astigmatism.

METHODS

This is an observational, cross-sectional study. We studied 116 consecutive myopic eyes with -3 diopters (D) or more of astigmatism that underwent LASIK surgery. The magnitude of uncorrected residual refractive astigmatism 3 months postoperatively was measured.

RESULTS

The mean preoperative cylinder was -4.0±0.83 D (range, -7.5 to -3 D) and the mean preoperative ORA was 0.82±0.5 D. The mean residual refractive cylinder 3 months postoperatively was -0.78±0.83 D (range, -3 to 0 D). No correlation was found between ORA and the refractive cylinder 3 months postoperatively (P=0.6).

CONCLUSION

In eyes with high myopic astigmatism undergoing LASIK, ORA was not correlated with the residual postoperative cylinder.

Early clinical outcomes of wavefront-guided myopic LASIK treatments using a new-generation hartmann-shack aberrometer

PURPOSE

To provide an initial retrospective evaluation of early postoperative outcomes after wavefront-guided myopic LASIK using a new-generation Hartmann-Shack wavefront sensor.

METHODS

A noncomparative, retrospective study of 243 eyes of 126 patients that underwent primary wavefront-guided LASIK, using wavefront data obtained with a new Hartmann-Shack aberrometer (iDesign Advanced WaveScan aberrometer; Abbott Medical Optics, Inc., Santa Ana, CA). Visual acuity, refraction, and patient satisfaction were evaluated 1 month after surgery.

RESULTS

The manifest spherical equivalent was reduced from -3.28 ± 1.79 diopters (D) (range: -9.88 to -0.38 D) before surgery to -0.03 ± 0.29 D (range: -1.00 to +1.25 D) 1 month after surgery. The manifest spherical equivalent was within 0.50 and 1.00 D of target in 93.0% and 99.6% of eyes, respectively. Manifest astigmatism preoperatively (-0.72 ± 0.67 [range: 0.0 to -5.00 D]) was reduced to -0.14 ± 0.20 (range: 0.0 to -1.00 D) at 1 month and the vector-derived correction ratio (surgically induced refractive change/intended refractive correction) was 1.02 ± 0.30. Uncorrected distance visual acuity of 20/16, 20/20, and 20/25 or better was achieved in 79.0%, 93.4%, and 96.7% of eyes, respectively. No eyes lost two or more lines of corrected distance visual acuity, whereas a gain of one or more lines was observed in 14.0%. Most patients (98.5%) reported that they were satisfied with the outcome of their procedure.

CONCLUSIONS

Wavefront-guided LASIK using the new aberrometer in this retrospective evaluation was effective, safe, and predictable in the early postoperative time period for the correction of myopia with high patient satisfaction.

Laser-assisted in situ keratomileusis in high mixed astigmatism with optimized, fast-repetition and cyclotorsion control excimer laser

PURPOSE

To evaluate the visual refractive and aberrometric outcomes of laser-assisted in situ keratomileusis (LASIK) surgery for the correction of high mixed astigmatism using a new-generation excimer laser and optimized aspherical profiles.

DESIGN

Retrospective interventional case series.

METHODS

Fifty-two eyes of 36 patients (21-53 years) with primary mixed astigmatism over 3.0 diopters (D) were included. All cases underwent LASIK surgery using the sixth-generation excimer laser Amaris with cyclotorsion control and a femtosecond platform for flap creation. Visual, refractive, corneal topographic, and aberrometric outcomes were evaluated during a 3-month follow-up. Refractive astigmatic changes were analyzed by Alpins method.

RESULTS

A significant reduction of refractive sphere and cylinder was observed 3 months postoperatively (P = .001), with an associated improvement of uncorrected distance visual acuity (P = .001). Best-corrected distance visual acuity (CDVA) remained unchanged in 31 eyes (59.6%), while 3 eyes (5.76%) lost 2 lines of CDVA. Fourteen eyes (26.9%) had spherical equivalent (SE) within ±0.5 D of emmetropia and 34 (65.3%) had SE within ±1.0 D of emmetropia. No significant difference was observed when comparing surgically induced and target astigmatism. A significant induction of higher-order aberration attributable to increase of spherical aberration was found (P = .003). Seven eyes (13.4%) required retreatment.

CONCLUSIONS

LASIK for primary high mixed astigmatism using optimized aspherical profiles and a fast-repetition-rate excimer laser with cyclotorsion control is a safe, effective, and predictable procedure. Induction of higher-order aberrations is still present in the correction of the refraction error of the magnitude included in this study.

Visual acuity after laser in situ keratomileusis to correct high astigmatism in adults with meridional amblyopia

PURPOSE

To analyze the effect of laser in situ keratomileusis to correct high myopic astigmatism in patients with suboptimal best spectacle-corrected visual acuity (BSCVA).

DESIGN

Retrospective, interventional series of consecutive cases.

METHODS

SETTING

Vissum Madrid, Madrid, Spain.

PATIENTS

Two hundred five eyes of consecutive patients with suboptimal BSCVA and high myopic astigmatism of -3 diopters or more.

INTERVENTION

Laser in situ keratomileusis surgery.

MAIN OUTCOME MEASURES

BSCVA.

RESULTS

The BSCVA (decimal Snellen fraction notation) improved significantly (P = .0001) from a mean preoperative 0.77 ± 0.18 (range, 0.05 to 0.90) to 0.81 ± 0.19 (range, 0.05 to 1.25) 3 months after surgery. The mean change in lines of BSCVA (decimal Snellen fraction notation) was 0.04 ± 0.11 (range, -0.25 to 0.4). A significant inverse relationship (P = .001) was found between the preoperative BSCVA and the improvement in BSCVA.

CONCLUSIONS

In eyes with high myopic astigmatism and suboptimal preoperative BSCVA, laser in situ keratomileusis may result in a significant improvement in BSCVA.

Static and dynamic rotational eye tracking during LASIK treatment of myopic astigmatism with the Zyoptix laser platform and Advanced Control Eye Tracker

PURPOSE

To evaluate the amount of cyclotorsion and the effect of static and dynamic rotational eye tracking with the Advanced Control Eye Tracker (Bausch & Lomb) based on iris recognition in the treatment of myopic astigmatism with LASIK.

METHODS

All patients with myopic LASIK and attempted cylinder correction >0.75 diopters (D) on the Zyoptix 217z100 excimer laser platform between May 2005 and May 2007 were identified retrospectively through the existing databank. Pre- and postoperative refraction and the amount of cyclotorsion during treatment were extracted and analyzed in 828 eyes with >3-month follow-up.

RESULTS

Preoperative mean manifest refraction spherical equivalent (MRSE) was -4.31+/-1.84 D (range: -0.37 to -9.50 D), and mean cylinder was -1.27+/-0.87 D (range: -0.75 to -6.75 D). Mean static rotation was 3.96+/-2.96 degrees (maximum 14.8 degrees ). Median dynamic rotation was 1.32+/-1.85 degrees (maximum 24 degrees). At 3 months postoperatively, MRSE was -0.10+/-0.36 D (range: -2.25 to +1.25 D), and mean cylinder was -0.33+/-0.35 D (range: -2.00 to 0 D). Predictability was 90.2% within +/-0.50 D and 98.2% within +/-1.00 D (MRSE), and 82.5% within +/-0.50 D and 96.9% within +/-1.00 D (cylinder). The efficacy ratio was 0.99. Safety was 99.4% (5 dry eyes), reaching 100% at 12 months. Stability from 3 to 12 months (n=275) was 98.2% for sphere, 95.3% for cylinder, and 96.0% for MRSE.

CONCLUSIONS

Our study demonstrates that significant cyclotorsion occurs before and during treatment. By using the dynamic rotational eye tracker presented, the efficacy of cylinder correction can be improved compared to those studies not performing cyclotorsional correction.

Laser in situ keratomileusis for mixed astigmatism using a modified formula for bitoric ablation

PURPOSE

To evaluate the results of treatment of mixed astigmatism with laser in situ keratomileusis (LASIK) by means of a modified Chayet formula for bitoric ablation and personalized nomogram calculations.

METHODS

A retrospective study was conducted in 19 consecutive eyes of 13 patients who underwent LASIK treatment of mixed astigmatism with a mean sphere of +1.63-/+1.23 D and a mean cylinder of -3.55-/+1.17 D. The authors used the Schwind ESIRIS Laser platform. The ablation was shifted from the pupil center to the vertex normal of the cornea.

RESULTS

Three months postoperatively, the mean sphere was 0.08-/+0.24 D and the mean astigmatism -0.45-/+0.31 D. At 3 months, an uncorrected visual acuity (UCVA) of 20/50 or better could be found in 100% of the eyes, and of 20/25 or better in 59%. All eyes were within -/+0.5 D spherical equivalent (SE) at 3, 6, and 12 months. No eye lost more than one line of best spectacle-corrected visual acuity (BSCVA). Postoperatively, the corneal wavefront showed a reduction of spherical aberrations and coma, which were analyzed at 4 and 6 mm pupil diameter. The postoperative higher-order aberrations decreased at 4 mm and increased at 6 mm pupil sizes after surgery.

CONCLUSIONS

Modified bitoric treatment with the Schwind ESIRIS laser showed an excellent postoperative UCVA and BSCVA with applying external nomogram adjustments. The method demonstrated good predictability, safety, and effectiveness in the treatment of mixed astigmatism.

Assessment and statistics of surgically induced astigmatism

The aim of the thesis was to develop methods for assessment of surgically induced astigmatism (SIA) in individual eyes, and in groups of eyes. The thesis is based on 12 peer-reviewed publications, published over a period of 16 years. In these publications older and contemporary literature was reviewed(1). A new method (the polar system) for analysis of SIA was developed. Multivariate statistical analysis of refractive data was described(2-4). Clinical validation studies were performed. The description of a cylinder surface with polar values and differential geometry was compared. The main results were: refractive data in the form of sphere, cylinder and axis may define an individual patient or data set, but are unsuited for mathematical and statistical analyses(1). The polar value system converts net astigmatisms to orthonormal components in dioptric space. A polar value is the difference in meridional power between two orthogonal meridians(5,6). Any pair of polar values, separated by an arch of 45 degrees, characterizes a net astigmatism completely(7). The two polar values represent the net curvital and net torsional power over the chosen meridian(8). The spherical component is described by the spherical equivalent power. Several clinical studies demonstrated the efficiency of multivariate statistical analysis of refractive data(4,9-11). Polar values and formal differential geometry describe astigmatic surfaces with similar concepts and mathematical functions(8). Other contemporary methods, such as Long's power matrix, Holladay's and Alpins' methods, Zernike(12) and Fourier analyses(8), are correlated to the polar value system. In conclusion, analysis of SIA should be performed with polar values or other contemporary component systems. The study was supported by Statens Sundhedsvidenskabeligt Forskningsråd, Cykelhandler P. Th. Rasmussen og Hustrus Mindelegat, Hotelejer Carl Larsen og Hustru Nicoline Larsens Mindelegat, Landsforeningen til Vaern om Synet, Forskningsinitiativet for Arhus Amt, Alcon Denmark, and Desirée and Niels Ydes Fond.

Sequential Ablation Approach to the Correction of Mixed Astigmatism

PURPOSE

To evaluate the safety, efficacy, and stability of LASIK, using positive cylinder and negative sphere nomograms in sequence (sequential ablation) to correct mixed astigmatism.

METHODS

This prospective study included 40 eyes of 20 patients with mixed astigmatism. Patients underwent bilateral sequential ablation LASIK using the Technolas 217 excimer laser (Bausch & Lomb Surgical, Rochester, NY). The main outcome measures, uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), were evaluated 3 and 12 months after surgery.

RESULTS

Preoperative astigmatism ranged from +1.75 to +6.00 diopters (D) and negative sphere from -0.50 to -3.00 D. The postoperative refraction at 3 months remained unchanged at 1 year postoperative in all patients. A total of 32 (80%) eyes showed no significant residual astigmatism (<0.50 D); the remaining 8 (20%) eyes had 0.50 to 1.00 D of residual astigmatism. Residual negative sphere was present in 2 eyes of 2 patients with a planned monovision target. In the remaining 38 (95%) eyes, no significant residual negative sphere was present. Sixteen (40%) eyes had one line of improvement in BSCVA. No eye lost lines of visual acuity. The efficacy index shows that uncorrected vision after surgery is equal or better than corrected vision before surgery. Less corneal tissue is removed and fewer laser spots are required compared to other techniques for the correction of mixed astigmatism.

CONCLUSIONS

The sequential ablation approach to the correction of mixed astigmatism was efficacious, safe, and stable 1 year after surgery.

Spherical aberration and contrast sensitivity after cataract surgery with the Tecnis Z9000 intraocular lens

PURPOSE

To determine whether implantation of an intraocular lens (IOL) with a modified prolate anterior surface (Tecnis Z9000, AMO) results in reduced spherical aberration and improved contrast sensitivity after cataract surgery.

SETTING

Hospital NISA Virgen del Consuelo, Valencia, Spain.

METHODS

In an intraindividual randomized prospective study of 30 patients with bilateral cataract, the Tecnis Z9000 IOL was compared with 2 IOLs with spherical surfaces, the AR40e (AMO) and the Stabibag (Ioltech). Ocular aberrations for a 4.0 mm pupil and 6.0 mm pupil were measured with a Hartmann-Shack aberrometer. Quality of vision was measured by visual acuity and contrast sensitivity under mesopic and photopic conditions.

RESULTS

Eyes with the Tecnis Z9000 IOL had significantly less spherical aberration and a greater Strehl ratio after surgery. Significant reduction in coma aberration was also found in some cases. Refraction, visual acuity, and contrast sensitivity were not significantly different between the 3 IOL groups.

CONCLUSION

A significant reduction in spherical aberration after Tecnis Z9000 IOL implantation was achieved, but visual acuity and contrast sensitivity were not affected by the aspheric silicone IOL compared to spherical acrylic IOLs.

Laser eye surgery for refractive errors

Several laser and non-laser refractive surgical procedures have been used to modify the shape of the cornea and correct myopia, hyperopia, astigmatism, and presbyopia. Introduction of the excimer laser to reshape the cornea has resulted in remarkable developments in the correction of these refractive errors. Combined with other advanced ophthalmological instruments, laser refractive eye surgery has resulted in a substantial rise in the safety, efficacy, and predictability of surgical outcomes. Despite these advances, certain limitations and complications persist. In this review, we describe the history, preoperative assessment, surgical techniques, outcomes, and complications of laser refractive surgery.

Optical Factors in Increased Best Spectacle-corrected Visual Acuity After LASIK

PURPOSE

To study the factors that correlate with improved best spectacle-corrected visual acuity (BSCVA) after LASIK.

METHODS

This was a nonrandomized, prospective clinical trial of 850 eyes from 480 patients undergoing LASIK for myopia, hyperopia, and mixed astigmatism. The mean preoperative spherical equivalent refraction was -3.75+/-4.82 diopters (D) (range: -13.88 to 6.00 D). From this population, 72 eyes (including 22 amblyopic eyes) from 43 patients were found to have improved BSCVA 6 months after LASIK. All patients underwent LASIK with the NAVEX platform. These eyes were analyzed to evaluate factors that correlated with improved BSCVA. Pre- and postoperative BSCVA, refraction, pupil diameter, corneal topography, asphericity (Q value), total aberrations, and higher order wavefront aberrations were analyzed. All wavefront aberrations were measured using the NIDEK Optical Path Difference Scan aberrometer (OPD-Scan) preoperatively and at 6 months postoperatively.

RESULTS

Postoperatively, the mean sphere was -0.44 1.30 D (range: -4.50 to +2.50 D). The mean increase in BSCVA was 0.15+/-0.09 logMAR. A statistically significant negative correlation was observed between the increase in BSCVA and the preoperative BSCVA (P<.01). Mixed astigmatic and highly myopic eyes are more likely to gain BSCVA after LASIK than moderately myopic (P<.05) and hyperopic eyes (P<.001). In patients with myopia, the amount of BSCVA improvement correlated with the magnitude of the correction (P<.05). The induction of spherical aberration negatively correlated with the increase in BSCVA (P<.05). There were no significant differences between normal eyes and amblyopic eyes with respect to postoperative improvement in BSCVA (P>.05).

CONCLUSIONS

Decreased preoperative BSCVA, lower total spherical aberration induction, and preoperative mixed astigmatism and high myopia correlate with an increase in BSCVA after LASIK.