Outcomes of Wavefront-Optimized Surface Ablation

Comparison of Outcomes after Wavefront-optimized and Topography-guided Transepithelial Photorefractive Keratectomy

PURPOSE

To evaluate the outcomes of wavefront-optimized (WFO) and topography-guided (TG) transepithelial photorefractive keratectomy (transPRK) in the treatment of myopia and myopic astigmatism.

METHODS

Patients who underwent transPRK using the WaveLight EX500 excimer laser for the correction of myopia and myopic astigmatism between January 2022 and March 2023 were divided into groups of WFO transPRK (77 eyes of 36 patients) or TG transPRK (63 eyes of 31 patients) in this retrospective, observational cohort study. The preoperative and postoperative 3-month refractive and visual outcomes of the two groups were analyzed.

RESULTS

In both groups, the uncorrected distance visual acuity was 0.0 logarithm of the minimum angle of resolution or better in 95% of eyes 3 months postoperatively, and the mean manifest refraction spherical equivalent was within ±1.0 diopter in 90% of eyes. No significant differences were observed between the groups in terms of the uncorrected distance visual acuity or astigmatism. A significant induction of higher order aberrations (HOAs) was observed in both groups. However, the induction of total corneal HOAs (p = 0.014) and spherical aberrations (p < 0.001) was significantly lower in the TG group than that in the WFO group.

CONCLUSIONS

WFO and TG transPRK effectively improved the visual and refractive outcomes; however, the induction of total corneal HOAs and spherical aberration was lesser following the TG ablation.

Quality of life and satisfaction among physicians after wavefront-optimized vs topography-guided laser vision correction

PURPOSE

To assess satisfaction, quality of life, occupational impact, and clinical outcomes of physicians who have undergone laser vision correction (LVC) using either wavefront-optimized (WFO) or topography-guided (TG) excimer laser ablation profile with femtosecond laser flap creation.

SETTING

Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA.

DESIGN

Retrospective survey study.

METHODS

A 12-question survey was sent to all physicians who underwent laser in situ keratomileusis or photorefractive keratectomy at the Cole Eye Institute between 2011 and 2018 on the WaveLight Allegretto Wave Eye-Q Laser (Alcon Laboratories, Inc.). Visual outcomes were obtained from patient charts.

RESULTS

Two hundred thirty-five physicians (454 eyes) met the study's inclusion criteria, including 181 physicians (353 eyes) who underwent WFO LVC and 54 physicians (101 eyes) who underwent TG LVC. One hundred seventeen physicians (49.8%) responded to the survey and reported an overall satisfaction rate of 98.3% among all physicians receiving LVC with 96.6% reporting they would have the procedure again. Visual outcomes showed a high level of surgical predictability, efficacy, and safety among WFO and TG eyes, with a higher percentage of eyes that received TG ablation achieving 20/10 vision (22% vs 4%, P < .0001) and 20/15 vision (87% vs 69%, P < .01) when compared with WFO eyes.

CONCLUSIONS

Physicians who had undergone LVC with either WFO or TG excimer laser ablation reported high satisfaction and quality-of-life improvements. Both groups achieved excellent visual outcomes, with a higher percentage of TG eyes achieving 20/10 and 20/15 vision.

Myopic Laser-Assisted Subepithelial Keratectomy (LASEK) outcomes using three different excimer laser platforms: a retrospective observational study

Background

To compare the visual and refractive outcomes after myopic LASEK using three different excimer lasers and standardized surgical and mitomycin C (MMC) application protocols.

Methods

In this retrospective, observational cohort study, we examined 122 eyes treated with Allegretto, 135 eyes treated with Esiris and 137 eyes treated with Technolas excimer lasers. All eyes were treated under the same surgical protocol, and a standardized MMC dosage was used. The three groups were refraction-matched, and both visual and refractive outcomes were evaluated at 1 and 7 days and 1 and 3 months after surgery.

Results

At 3 months postsurgery, Allegretto provided significantly better outcomes than Esiris and Technolas in terms of postoperative uncorrected distance visual acuity (UDVA) (1.11 ± 0.2 vs 1.01 ± 0.2 vs 0.98 ± 0.2) (P = 0.0001), corrected distance visual acuity (CDVA) (1.13 ± 0.2 vs 1.10 ± 0.1 vs 1.04 ± 0.2) (P = 0.0001), residual sphere (− 0.01 ± 0.2 vs + 0.29 ± 0.7 vs + 0.27 ± 0.6) (P = 0.0001), and efficacy index (0.99 ± 0.2 vs 0.90 ± 0.2 vs 0.91 ± 0.2) (P = 0.0004).

Conclusions

We found slightly better visual and refractive outcomes in the Allegretto group at 3 months post-op after LASEK with MMC to correct myopia.

Visual performance after excimer laser photorefractive keratectomy for high myopia

PURPOSE:

To evaluate the efficacy, safety, predictability, and visual performance of excimer laser photorefractive keratectomy (PRK) for myopia greater than −8 diopters (D).

METHODS:

Fifty-four patients (104 eyes) with myopia from −8D to −13D and cylinder up to −4D received surface ablation technique with the Allegretto wave version 1009-1 excimer laser to correct their refractive error. The patients were examined on days 1, 3, 7, and 14 and 1, 3, 6, and 12 months postoperatively. Visual acuity, manifest refraction, corneal haze, topography, intraocular pressure, contrast sensitivity, and wavefront aberration were evaluated.

RESULTS:

Twelve months postoperatively, 95% of eyes were within 1D of the intended correction. In addition, 94% of eyes had attained uncorrected distance visual acuity of 20/25 or better, and 98% of eyes had improved or remained their corrected distance visual acuity. All eyes exhibited barely detectable corneal haze which peaked during the 1^st month with a gradual reduction in the 3^rd month. Ninety-five percent of patients had no or only mild degree of night glare.

CONCLUSIONS:

Excimer laser PRK is an effective and predictive treatment for high myopia greater than −8D with or without astigmatism up to −4D. The incidence of complication is low. All patients who are candidates for laser in situ keratomileusis can be candidates for surface ablation, especially those with preoperative thinner cornea or higher risk of corneal flap complications.

Advanced Surface Ablation With a New Software for the Reduction of Ablation Irregularities

PURPOSE

To compare visual outcomes and postoperative aberrations after surface ablation performed with a 750-Hz versus a 1,050-Hz excimer laser coupled with an ablation software designed to reduce corneal surface irregularity.

METHODS

Retrospective comparative trial of myopic eyes that had refractive surgery consecutively treated with transepithelial advanced surface ablation with a 750-Hz excimer laser (750 group) versus a 1,050-Hz excimer laser coupled with the Smart Pulse Technology ablation software (SPT group). The SPT algorithm is a laser pulse technology software aimed at reducing surface irregularity of the stromal bed at the end of treatment. The authors evaluated the effect of this smoothing on final visual acuity. Patients were observed for 6 months.

RESULTS

A total of 139 eyes in the 750 group and 40 eyes in the SPT group were evaluated. Epidemiological and preoperative refractive data of the two groups were comparable. Uncorrected distance visual acuity improved with time and was significantly better in the SPT group (-0.04 ± 0.61 logMAR for the SPT group vs 0.02 ± 0.78 logMAR for the 750 group) (P < .001). At 6 months, 55% versus 21% achieved 20/16 or better (P = .005) and 90% versus 65% achieved 20/20 or better (P = .019) visual acuity in the SPT and 750 groups, respectively. Corrected distance visual acuity improved with time and appeared to be influenced by group (P = .054), with better results in the SPT group. Coma and trefoil improved significantly with time in a similar manner in both groups.

CONCLUSIONS

Surface ablation with the 1,050-Hz excimer laser and SPT software, aimed at reducing the final superficial stromal irregularity, led to improvement of 6-month uncorrected visual acuity. [J Refract Surg. 2017;33(2):89-95.].

Efficacy of Wavefront-guided Photorefractive Keratectomy with Iris Registration for Management of Moderate to High Astigmatism by Advanced Personalized Treatment Nomogram

Purpose:

To evaluate the efficacy of photorefractive keratectomy (PRK) using the advanced personalized treatment (APT) nomogram for correction of moderate to high astigmatism.

Methods:

This prospective interventional case series included 60 consecutive eyes of 30 patients undergoing wavefront-guided PRK (Zyoptix 217 Z100 excimer laser, Bausch & Lomb, Munich, Germany) using the APT nomogram and iris registration for myopic astigmatism. Mitomycin-C was applied intraoperatively in all eyes. Ophthalmic examination was performed preoperatively and 1, 3 and 6 months postoperatively.

Results:

Preoperatively, mean sphere was -1.68 ± 2.08 diopters (D), mean refractive astigmatism was -3.04 ± 1.05 D and mean spherical equivalent (SE) was -3.12 ± 1.77 D. Six months postoperatively, mean sphere was + 0.60 ± 0.64 D (P < 0.005), mean cylinder was -0.43 ± 0.46 D (P < 0.005) and mean SE was + 0.28 ± 0.48 D (P < 0.005). Hyperopic overcorrection (≥ +1.0 D) occurred in 3 (5%) eyes. Postoperatively, root mean square (RMS) of higher order aberrations (HOAs) was significantly increased (P = 0.041). RMS of spherical aberration (Z [4, 0]) showed no significant change after surgery (P = 0.972).

Conclusion:

Considering the acceptable residual refractive error, low rate of hyperopic overcorrection, acceptable uncorrected visual acuity, and low risk of postoperative corneal haze, PRK using the APT nomogram with iris registration and mitomycin-C use is a safe and effective modality for treatment of moderate to high astigmatism.

Prospective contralateral eye study to compare 80- and 120-μm flap LASIK using the VisuMax femtosecond laser

PURPOSE

To compare visual outcomes and flap stability of LASIK with ultrathin 80- and 120-μm flaps created with a VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) for moderate to high myopia and to evaluate the effect of corneal flap thickness on outcomes.

METHODS

In a prospective contralateral eye study, 36 consecutive patients (72 eyes) underwent bilateral LASIK for myopia ranging from -2.00 to -10.00 diopters using the VisuMax femtosecond laser and MEL-80 excimer laser (Carl Zeiss Meditec). One eye of each patient was randomized to have the 80-μm flap and the other to the 120-μm flap created with 200-kHz VisuMax femtosecond laser. Preoperative and postoperative tests included visual acuity, manifest refraction, contrast sensitivity, and flap thickness measured by anterior segment optical coherence tomography. Main outcomes and complications were checked at postoperative 1 week and 1, 3, and 6 months.

RESULTS

There were no differences in visual outcome, residual refractive error, or contrast sensitivity between groups during follow-up, except for better uncorrected visual acuity at postoperative 1 day in the 120-μm group. Mean standard deviations of measured flap thickness during follow-up ranged from 3.16 to 3.80 μm in both groups. Opaque bubble layer, a unique complication in femtosecond LASIK, was more frequent in the 80-μm group (7 of 36: 19%) than in the 120-μm flap group (3 of 36: 8%) without a statistically significant difference (P = .301) and was related to thicker central cornea and steeper keratometric value, although it did not influence clinical results. Comparison of the intended versus achieved correction showed no significant differences between groups.

CONCLUSIONS

LASIK using the VisuMax femtosecond laser supplied good clinical results and flap reproducibility in both the 80- and 120-μm flap groups. Patients with relatively thin cornea may benefit from 80-μm flap LASIK.

Flap-off epi-LASIK versus automated epithelial brush in PRK: a prospective comparison study of pain and reepithelialization times

PURPOSE

To compare the effect of flap-off epi-LASIK versus automated brush epithelial removal on pain and wound healing in low myopic photorefractive keratectomy (PRK).

METHODS

In this prospective intraindividual study 60 patients received surface ablation in each eye. Epithelial removal was performed by an automated brush technique in one eye (brush group) and epi-LASIK with flap removal (flap-off group) in the fellow eye. The epithelial defect size was measured daily after surgery until both eyes were reepithelialized. Postoperative pain on a scale from 0 to 6 and topical and oral analgesic medication use was recorded until the bandage contact lens was removed.

RESULTS

The flap-off group had significantly less postoperative pain on days 1 (P=.0003), 2 (P=.0001), 3 (P<.0001), and 4 (P<.0001) compared to the brush group. However, the average difference in pain scores between groups was only 0.33 points out of 6. No difference was noted in the normalized overall percentage rate of healing over the first 4 days in the flap-off group (5.41±1.39%/hour) compared to the brush group (5.42±1.94%/hour) (P=.97).

CONCLUSIONS

The flap-off group showed a statistically but not clinically significant advantage over the brush group in pain scores. However, no difference was noted in the percentage rate of epithelial healing time between the two groups.

Aspheric wavefront-guided versus wavefront-guided LASIK for myopic astigmatism with the Technolas 217z100 excimer laser

PURPOSE

To compare clinical outcomes of wavefront-guided LASIK with and without aspheric compensation in myopic eyes.

METHODS

In this observational, single-center study, 134 eyes were treated using an aspheric module in combination with wavefront-guided profiles (PTA-algorithm) and compared to 146 eyes treated with the predecessor wavefront-guided software (APT) that has no aspheric compensation. All treatment plans included the Rochester nomogram that accounts for the preoperative manifest refraction and interaction of higher order aberrations. Active eye-tracking (including cyclorotational movements) was utilized during photoablation.

RESULTS

Results at the 3-month follow-up: 67 % of PTA-treated eyes and 39 % of APT-treated eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 or better. Change in mean higher order aberration root-mean-square (HOA RMS) after PTA treatments was not statistically significant (p = 0.18). The increase in HOA RMS after APT treatments was statistically significant (p = 0.003). Change in mean postop spherical aberration (SA) after PTA treatments was not statistically significant (p = 0.27). The change in SA after APT treatments was statistically significant (p = 0.001). In both cohorts, mean uncorrected low-contrast visual acuity was statistically not different to preoperative corrected values.

CONCLUSIONS

Adding an aspheric compensation to wavefront-guided myopic LASIK statistically improved clinical results in terms of visual acuity and refractive outcomes. Low-contrast visual acuity was not negatively affected in either group. While in APT-treated eyes mean HOA RMS and mean SA were significantly increased postoperatively, PTA-treated eyes showed neither induced HOA RMS nor induced SA.

Custom vs conventional PRK: a prospective, randomized, contralateral eye comparison of postoperative visual function

PURPOSE

To determine whether VISX S4 (VISX Inc) custom photorefractive keratectomy (PRK) results in better visual outcomes than VISX S4 conventional PRK.

METHODS

Photorefractive keratectomy was performed on 80 eyes from 40 patients in this randomized, prospective, contralateral eye study. Dominant eyes were randomized to one group with the fellow eye receiving the alternate treatment. Primary outcome measures included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), contrast sensitivity, and root-mean-square (RMS) higher order aberrations.

RESULTS

Mean UDVA was -0.023±0.099 (20/19) in the custom group and -0.044±0.080 (20/18) in the conventional group 6 months after surgery (P=.293). Mean CDVA was -0.073±0.067 (20/17) in the custom group and -0.079±0.071 (20/17) in the conventional group 6 months after surgery (P=.659). Total higher order aberration RMS and spherical aberration increased in both groups compared to preoperative values (P<.05). Coma increased in the conventional group (P<.05) whereas it was similar to preoperative values in the custom group. No significant differences were noted in induction of trefoil.

CONCLUSIONS

Custom and conventional PRK were shown to be safe and effective with excellent visual acuity and contrast sensitivity performance at 6 and 12 months. Conventional PRK induced more coma than custom PRK; however, this did not seem to correlate with clinical outcomes.

Infectious keratitis in 18,651 laser surface ablation procedures

PURPOSE

To evaluate the incidence, culture results, risk factors, treatment strategies, and visual outcomes of infectious keratitis after surface ablation.

SETTING

Multicenter study in Spain.

DESIGN

Case series.

METHODS

The medical records of patients who had surface ablation between January 2003 and December 2009 were reviewed to identify cases of infectious keratitis. The incidence, risk factors, clinical course, days to diagnosis, medical and surgical treatment, and visual outcome were recorded. Main outcome measures were incidence of infectious keratitis after surface ablation, culture results, response to treatment, and visual outcomes.

RESULTS

The study reviewed the records of 9794 patients (18,651 eyes). Infectious keratitis after surface ablation was diagnosed in 39 eyes of 38 patients. The onset of infection was early (within 7 days after surgery) in 28 cases (71.79%). Cultures were positive in 13 of 27 cases in which samples were taken. The most frequently isolated microorganism was Staphylococcus species (9 cases). The final corrected distance visual acuity (CDVA) was 20/20 or better in 23 cases (58.97%), 20/40 or better in 36 cases (92.30%), and worse than 20/40 in 3 cases (7.69%).

CONCLUSIONS

The incidence of infectious keratitis after surface ablation was 0.20%. Infectious keratitis is a potentially vision-threatening complication. Prompt and aggressive management with an intensive regimen of fortified antibiotic agents is strongly recommended. Proper management can preserve useful vision in most cases.

FINANCIAL DISCLOSURE

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

Mitomycin C-assisted photorefractive keratectomy in high myopia: a long-term safety study

PURPOSE

To evaluate the long-term corneal safety of topical mitomycin C (MMC) used during photorefractive keratectomy to prevent haze formation in highly myopic eyes.

METHODS

Twenty-eight patients with bilateral high myopia underwent photorefractive keratectomy. One eye was randomly assigned to intraoperative 0.02% MMC and the fellow eye to conventional treatment. Each eye was checked at baseline and at 5 years after surgery using in vivo corneal confocal microscopy.

RESULTS

At baseline, the endothelial cell density was 2970 ± 295 cells per square millimeter in the MMC-treated eyes and 2839 ± 323 cells per square millimeter in the control eyes. At 5 years, it was 2803 ± 307 and 2780 ± 264 cells per square millimeter, respectively (P = 0.27). The number of corneal nerve fibers was 3.9 ± 1.6 in the MMC-treated eyes and 4.4 ± 1.3 in the control eyes. At 5 years, it was 3.0 ± 1.6 and 2.7 ± 1.3, respectively (P = 0.15). The density of corneal nerves was 9600 ± 2915 μm/mm(2) in the MMC-treated eyes and 11,352 ± 3898 μm/mm(2) in the control eyes. At 5 years, the density was higher in the MMC-treated eyes (6790 ± 2447 μm/mm(2)) than in the control eyes (6024 ± 2977 μm/mm(2)) (P = 0.003). The number of nerve beadings at baseline was 12.9 ± 1.7/100 μm in the MMC-treated eyes and 12.3 ± 2.0/100 μm in the control eyes. At 5 years, it was 9.9 ± 2.6/100 and 9.4 ± 2.9/100 μm, respectively (P = 1.00). At 5 years, corneal nerve branching and tortuosity were similar in the 2 groups (P = 0.88 and 0.54, respectively). Epithelium thickness remained statistically unchanged (P = 0.69).

CONCLUSIONS

Intraoperative use of topical 0.02% MMC compared with standard treatment does not induce significant long-term corneal changes, as assessed by in vivo corneal confocal microscopy.

Effects of advanced surface ablations and intralase femtosecond LASIK on higher order aberrations and visual acuity outcome

BACKGROUND/AIMS

To study the changes in wavefront (ocular) and corneal higher order aberrations (HOAs) and visual acuity (VA) outcome following wavefront-guided advanced surface ablation (ASA) techniques and intralase femtosecond LASIK (iLASIK) in myopia treatment.

METHODS

Ocular aberration and corneal topography of 240 eyes in the ASA techniques (this was equally divided into a flap-on group where the epithelial flap was preserved and reapplied to the photoablated stromal bed and a flap-off group when the epithelial flap was discarded during the procedure), and 138 eyes in the iLASIK group were obtained before and 3 months following treatment. The correlation of aberrations with best spectacle-corrected visual acuity was analyzed.

RESULTS

At 3 months, there was statistically significant (P < 0.001) surgically induced increase in spherical aberration (SA) in each of the techniques for both ocular and corneal analysis. iLASIK induced significantly less ocular and corneal HOAs (P < 0.001). The mean manifest refractive spherical equivalent was closer to attempted correction compared to other groups (P < 0.001). Eighty-three eyes (70%) of flap-on, 80 (67%) flap-off and 94 eyes (68%) in the iLASIK group achieved 20/20 uncorrected VA. Fifteen eyes (11%) accomplished 20/12.5 or better in iLASIK compared to 4 (3%) for flap-on and 7 (6%) for flap-off ASA group. Only the flap-off treatment showed a consistent correlation between the corrected aberrations and visual performance.

CONCLUSION

At 3 months, all procedures resulted in a significant increase in HOAs and SA. All had comparable 20/20 VA and 11% of iLASIK patients achieved 20/12.5 or better level.

Surface ablation techniques

The ongoing quest for a safe, simple, effective, minimally invasive, and stable refractive surgical procedure to correct refractive errors has stimulated the development of surface ablation techniques and laser in situ keratomileusis. In this review, we describe the history, patient assessment, techniques, outcomes, and complications of surface ablation (photorefractive keratectomy, laser-assisted sub-epithelial keratectomy, epithelial laser-assisted in situ keratomileusis) and compare the results of various surface techniques. Surface ablation procedures will continue to evolve, with potential improvements in outcomes accompanying future sophisticated ablation profiles and laser technology.

Wavefront-optimized surface ablation with the Allegretto Wave Eye-Q excimer laser platform: 12-month visual and refractive results

PURPOSE

To evaluate the wavefront-optimized algorithm of the Allegretto Wave Eye-Q (Wavelight AG) 400-Hz excimer laser platform.

METHODS

Three hundred three eyes of 303 patients treated with advanced surface ablation were evaluated prospectively. Topical mitomycin C (MMC) was used when ablation was ≥80 μm. Efficacy, safety, and predictability at 12 months were quantified with subjective refraction, visual acuity (logMAR), and slit-lamp examination.

RESULTS

Mean postoperative uncorrected distance visual acuity (UDVA) was 20/20.5 (0.01±0.05 logMAR). Postoperative UDVA was equal or better than preoperative corrected distance visual acuity (CDVA) in 94.7% of eyes. Efficacy index was 1.05. Corrected distance visual acuity was maintained (93.7%) or improved (5.9%) in 99.6% of treated eyes. No patient lost ≥2 lines. Safety index was 1.05. Haze at 12 months was grade ≤0.5 in 98% of treated eyes and grade ≤1 in 100% of treated eyes. Mean postoperative manifest refraction spherical equivalent (MRSE) was -0.03±0.15 diopters (D). Postoperative MRSE was within ±0.50 D in 99% of eyes. Overcorrection was documented in 0.66% and undercorrection in 0.33% of eyes.

CONCLUSIONS

The wavefront-optimized algorithm of the Allegretto Wave Eye-Q excimer laser platform showed good efficacy, safety, and predictability in advanced surface ablation, with or without MMC intraoperative use.

Higher-order aberration changes after Implantable Collamer Lens implantation for myopia

PURPOSE

To investigate the changes in higher-order aberrations (HOAs) induced by implantation of Implantable Collamer Lenses (STAAR Surgical) and to explain them in relation to the surgical incision and optical properties.

DESIGN

Prospective, observational case study.

METHODS

This study included 56 eyes undergoing Implantable Collamer Lens insertion for myopic correction. The corneal incision size was determined according to the amount of astigmatism. HOAs were measured before surgery and 3 months after surgery in 25 eyes having small superior incision (<3.2 mm) surgery and in 31 eyes with large superior incision (3.2 to 4.5 mm) surgery. Changes in spherical aberration, coma, trefoil, and total HOAs (third to sixth order) were analyzed. Laboratory measurements of aberration profiles of Implantable Collamer Lenses with different optical powers were performed to validate clinical measurements.

RESULTS

In the small-incision group, trefoil (Z(3)(-3)) and spherical aberration changed significantly (P=.004). In the large-incision group, in addition to trefoil and spherical aberration, total HOA changed significantly (mean change, 0.13 ± 0.17; P=.001). Significant correlations were observed among the incision size, the astigmatism induced, and the trefoil induced. Induced trefoil showed a predominant pattern at the orientation of the incision meridian. Optical measurement of aberrations of the Implantable Collamer Lenses confirmed the postoperative negative spherical aberration.

CONCLUSIONS

HOA changes after Implantable Collamer Lens insertion were increased trefoil and induced negative spherical aberration. These changes may be explained by the effect of the corneal incision and the negative spherical aberration in the Implantable Collamer Lens, respectively.

Influence of flap thickness on visual and refractive outcomes after laser in situ keratomileusis performed with a mechanical keratome

PURPOSE

To study the effect of flap thickness on visual acuity and refractive outcomes after laser in situ keratomileusis (LASIK) using 2 blade types with a mechanical microkeratome.

SETTING

Emory Vision, Atlanta, Georgia, USA.

METHODS

This retrospective analysis was of LASIK cases performed between January 2005 and June 2006 using an Amadeus I microkeratome and an ML7090 CLB blade (blade A) or a Surepass blade (blade B). Outcomes analyzed included flap thickness, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), the enhancement rate, and surgical complications 3 months postoperatively.

RESULTS

Two hundred sixty-three eyes of 153 patients were analyzed; blade A was used in 158 eyes and blade B, in 105 eyes. The mean flap thickness was significantly thinner with blade A than with blade B (107 microm +/- 12 [SD] versus 130 +/- 20 microm) (P<.0001). There was no overall correlation with either blade between flap thickness and UDVA, CDVA, or MRSE (all r<0.2). At 3 months, there was no statistically significant difference in UDVA, CDVA, or MRSE between the 2 blade groups at 3 months (all P > .10), and there was no difference in the complication rates.

CONCLUSION

Flap thickness did not affect visual or refractive outcomes with a mechanical microkeratome with either blade type.

One-year outcomes of a bilateral randomised prospective clinical trial comparing PRK with mitomycin C and LASIK

AIM

To compare 1-year follow-up results of photorefractive keratectomy (PRK) with mitomycin C (MMC) and laser in situ keratomileusis (LASIK) for custom correction of myopia.

METHODS

Eighty-eight eyes of 44 patients with moderate myopia were randomised to PRK with 0.002% MMC for 1 min in one eye and LASIK in the fellow eye. The 1-year follow-up was evaluated.

RESULTS

There were no differences between LASIK and MMC-PRK eyes preoperatively. Forty-two patients completed the 1-year follow-up. MMC-PRK eyes achieved better uncorrected visual acuity (p = 0.03) and better best-spectacle-corrected visual acuity (p<0.001) 1 year after surgery. SE did not differ in the two groups during follow-up (p = 0.12). Clinically significant haze was not found in surface ablation eyes. LASIK eyes showed a greater higher-order aberration (p = 0.01) and lower contrast sensitivity (p<0.05) than MMC-PRK eyes postoperatively. Excellent vision was reported in 64% of LASIK and 74% of MMC-PRK eyes 1 year after surgery. The corneal resistance factor and corneal hysteresis (ORA, Reichert) were higher in LASIK than in MMC-PRK eyes (p<0.01) at the last follow-up.

CONCLUSIONS

Wavefront-guided PRK with 0.002% MMC was more effective than wavefront-guided LASIK for correction of moderate myopia. Further research is necessary to determine the optimal concentration, exposure time and long-term corneal side effect of MMC.

Incidence, outcomes, and risk factors for retreatment after wavefront-optimized ablations with PRK and LASIK

PURPOSE

To analyze and compare retreatment rates after wavefront-optimized photorefractive keratectomy (PRK) and LASIK and determine risk factors for retreatment.

METHODS

A retrospective chart review was performed to identify patients undergoing PRK or LASIK with the wavefront-optimized WaveLight platform from January 2005 through December 2006 targeted for a piano outcome and to determine the rate and risk factors for retreatment surgery in this population.

RESULTS

Eight hundred fifty-five eyes were analyzed, including 70 (8.2%) eyes with hyperopic refractions and 785 (91.8%) eyes with myopic refractions. After initial treatment, 72% of eyes were 20/20 or better and 99.5% were 20/40 or better. To improve uncorrected visual acuity, 54 (6.3%) eyes had retreatments performed. No significant differences in retreatment rates were noted based on age (P = .15), sex (P = .8), eye (P = .3), PRK versus LASIK (P = 1.0), room temperature (P = .1) or humidity (P = .9), and no correlation between retreatment rate and month or season of primary surgery (P = .4). There was no correlation between degree of myopia and retreatment rate. Eyes were significantly more likely to undergo retreatment if they were hyperopic (12.8% vs 6.0%, P = .006) or had astigmatism > or = 1.00 diopter (D) (9.1% vs 5.3%, P = .04).

CONCLUSIONS

Retreatment rate was 6.3% with the WaveLight ALLEGRETTO WAVE excimer laser. This rate was not influenced by age, sex, corneal characteristics, or environmental factors. Eyes with hyperopic refractions or astigmatism > or = 1.00 D were more likely to undergo retreatment.

Advanced personalized nomogram for myopic laser surgery: first 100 eyes

PURPOSE

To report the results in the first 100 eyes treated for myopia using a new advanced nomogram.

SETTING

Private refractive surgery clinic.

METHODS

This prospective interventional case series comprised 58 patients (100 eyes) consecutively treated for myopia with laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) performed by the same surgeon. All treatments used a new nomogram for the Zyoptix 217 Z100 excimer laser. Postoperative mean sphere, cylinder, and spherical equivalent (SE) refraction were evaluated 3 months postoperatively. Safety, efficacy, and predictability were also evaluated.

RESULTS

In the LASIK group (34 eyes), the mean postoperative sphere was +0.18 diopters (D) +/- 0.47 (SD), the mean postoperative cylinder was -0.10 +/- 0.23 D, and the mean postoperative SE was 0.04 +/- 0.36 D. In the LASEK group (64 eyes), the respective means were 0.10 +/- 0.22 D, -0.05 +/- 0.13 D, and +0.03 +/- 0.16 D. Hyperopic overcorrection (> or = +1.00 D) occurred in 4.1% of patients. Ninety-five percent of eyes in the LASIK group and 97% of eyes in the LASIK group had an uncorrected visual acuity of 1.0 (20/20) or better. Patient satisfaction was slightly higher than that of other laser refractive surgery patients at the clinic.

CONCLUSIONS

The use of the advanced nomogram increased treatment accuracy in terms of UCVA and postoperative mean refraction and reduced the rate of hyperopic overcorrection over that in earlier studies. The need for enhancement procedures was reduced, and patient satisfaction was high.

Thin-flap laser-assisted in situ keratomileusis

PURPOSE OF REVIEW

Concerns regarding the increasing incidence of corneal ectasia following laser in situ keratomileusis procedures, together with increased understanding of the biomechanics of the cornea, has resulted in many refractive surgeons returning to surface ablation techniques such as photorefractive keratectomy. Even if surface ablation techniques offer a higher degree of safety than LASIK, they are associated with more pain and a slower visual recovery in the immediate postoperative period. This highlights the need for alternative procedures that offer the combined advantages of laser in situ keratomileusis and photorefractive keratectomy.

RECENT FINDINGS

Sub-Bowman's keratomileusis is a new procedure that provides the biomechanical stability and associated safety of photorefractive keratectomy with the visual results and reduced pain experience of laser in situ keratomileusis. This technique involves the use of the femtosecond laser to create a customized corneal flap of between 90 and 110 mum with a diameter based on the requirements of the individual patient and the type of excimer laser being used.

SUMMARY

This review outlines the rationale for sub-Bowman's keratomileusis and describes the efficacy, tolerability and safety of the procedure compared with photorefractive keratectomy.

Current trends in advanced surface ablation

PURPOSE OF REVIEW

Since their introduction in the mid-1990s, surface ablation techniques have continued to evolve, enabling surgeons to give patients better quality of vision with less postoperative pain. The purpose of this chapter is to discuss that evolution, the common techniques used today, and how to address potential complications.

RECENT FINDINGS

Advanced surface ablation techniques offer advantages over laser in situ keratomileusis, including expanded potential patient profiles, reduced haze and pain postoperatively, and increased quality of vision. Haze reduction via preserved epithelial flaps, smoother stromal beds, and introduction of mitomycin-C intraoperatively have all improved safety outcomes of advanced surface ablation.

SUMMARY

Experience has shown us that virtually all patients who are candidates for laser in situ keratomileusis can be candidates for surface ablation, but patients with specific ocular conditions, such as epithelial basement membrane dystrophy, superficial corneal scars, and previous radial keratotomy will have the best outcomes with surface ablation. Surface ablation and laser in situ keratomileusis are comparable in terms of safety and quality of vision. Wavefront-guided photorefractive keratectomy offers better acuity and less induction of higher order aberrations than wavefront-guided laser in situ keratomileusis.

Wavefront-guided excimer laser ablation using photorefractive keratectomy and sub-Bowman's keratomileusis: a contralateral eye study

PURPOSE

To explain the basic science and clinical evidence that has led to the development of a new technique in corneal refractive surgery--sub-Bowman's keratomileusis (SBK).

METHODS

A comprehensive review of the literature and report of a contralateral eye study of 50 patients (100 eyes) enrolled at 2 sites (25 patients per site) and randomized according to the dominant eye was conducted. All eyes underwent a wavefront-guided refractive correction using the Alcon LADARVision4000 System. In one eye, an 8.5-mm, ETOH-assisted photorefractive keratectomy (PRK) was performed. In the second eye, an 8.5-mm, 100-microm flap was attempted using a 60 kHz IntraLase FS femtosecond laser. Pre- and postoperative tests included best spectacle-corrected visual acuity, uncorrected visual acuity, corneal topography, wavefront aberrometry, retinal image quality, contrast sensitivity, and biomechanical response of the cornea. Patients completed subjective questionnaires at each follow-up.

RESULTS

Clinical results demonstrate that SBK provides quicker visual recovery, although the data suggest that the 3- and 6-months results are similar in terms of visual outcomes. Reichert Ocular Response Analyzer results demonstrate that its impact on the cornea is similar to PRK.

CONCLUSIONS

This study indicates that SBK provides the visual recovery of a LASIK procedure with the Optical Response Analyzer results similar to PRK.