Wavefront-guided LASIK With the NIDEK NAVEX Platform for the Correction of Myopia and Myopic Astigmatism With 6-month Follow-up

Laser-assisted subepithelial keratomileusis with mitomycin C for myopic astigmatism ≥2.00 diopters using a Zeiss MEL 80 Excimer

To examine the refractive and visual outcome of laser-assisted subepithelial keratomileusis (LASEK) with mitomycin C(MMC) in eyes with myopic astigmatism ≥2.00 diopters (D). This study comprised 82 eyes of 82 consecutive patients (37 male, 45 female; mean age at surgery 34.7 ± 9.0 years) with preoperative topographic astigmatism ≥2.00 D and mean preoperative spherical equivalent (SE) -4.50 ± 1.13 D. To assess whether the refractive results differed with the amount of corrected sphere, the data were separated by preoperative SE thereby defining two groups with SE < -5.00 D (-2.00 to -4.75 D) and ≥-5.00 D (-5.00 to -7.75 D). Mean manifest refraction spherical equivalent (MRSE) of -0.39 ± 0.52 D was obtained at the 6-months (5.4 ± 1.6 months) follow-up. The results were within ±1.00 D of the attempted correction in 89 % of patients. The mean postoperative corrected distant visual acuity was -0.02 ± 0.065 logMAR (range -0.10 to 0.15 logMAR). Sixty-seven (81.7 %) of all eyes did not change lines in safety. There was no statistically significant difference (P = 0.262) in safety between the SE groups. Mean efficacy was 0.89 ± 0.27. There was a statistically significant difference in efficacy (P = 0.024) between the preoperative SE groups. Larger ablation zones were associated with better visual outcome, confirmed by safety, efficacy and predictability. The data reported here demonstrated that LASEK using a Zeiss MEL 80 excimer laser with an additional application of MMC is a safe and efficient technique with predictable results for the correction of eyes with myopic astigmatism ≥2.00 D.

Clinical outcomes of optimized prolate ablation and custom aspheric treatment in laser-assisted subepithelial keratectomy

PURPOSE

To compare visual acuity, refractive, wavefront, and visual quality outcomes between optimized prolate ablation (OPA) and optical path difference custom aspheric treatment (OPDCAT) algorithms for myopia correction.

SETTING

Private practice, Busan, South Korea.

DESIGN

Prospective randomized masked clinical trial.

METHODS

One eye of each patient was randomly selected to have laser-assisted subepithelial keratectomy with the OPA algorithm and the contralateral eye with the OPDCAT algorithm. Visual acuity, manifest refraction, ocular and corneal higher-order aberrations (HOAs), corneal asphericity (Q value), and modulation transfer function (MTF) in the 2 groups were compared 1, 3, and 6 months postoperatively.

RESULTS

The study enrolled 39 patients. The mean manifest refraction spherical equivalent at 6 months was 0.19 diopter (D) ± 0.37 (SD) in the aspheric ablation group and 0.00 ± 0.33 D in the prolate ablation group. Predictability (± 0.50 D from intended refraction) at 6 months was 82% and 100%, respectively. Twenty-six eyes (93%) in the aspheric ablation group and 27 (96%) in the prolate ablation group had an uncorrected distance visual acuity of 20/20 or better. One eye in the aspheric ablation group and no eye in the prolate ablation group lost 1 line of corrected distance visual acuity. The prolate ablation group had fewer induced corneal and ocular spherical aberrations than the aspheric ablation group. Corneal asphericity was unchanged postoperatively in the prolate ablation group. The MTF under the correction of lower-order aberrations was higher in the prolate ablation group than in the aspheric ablation group.

CONCLUSION

The prolate ablation algorithm gave more predictable visual outcomes, induced fewer corneal HOAs, and conserved more preoperative corneal asphericity than the aspheric algorithm.

FINANCIAL DISCLOSURE

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

Comparison of LASIK with the OPDCAT or OATz algorithm using the NIDEK EC-5000CXII excimer laser

PURPOSE

To compare refractive outcomes, higher order aberrations, visual quality, and patient satisfaction between aspheric and whole-eye wavefront aspheric LASIK algorithms.

METHODS

Two hundred seventy-four eyes of 152 patients undergoing LASIK for myopia and myopic astigmatism were divided into two groups: eyes that underwent treatment using either the OPD-guided customized aspheric treatment (OPDCAT) or optimized aspheric treatment zone (OATz). Both groups were subdivided into two groups based on preoperative manifest refraction spherical equivalent (MRSE) <or= 6.00 diopters (D) and eyes with MRSE >or = - 6.00 D. Both groups were additionally subdivided into eyes with preoperative ocular higher order aberrations <0.40 microm and eyes with higher order aberrations >or = 0.40 microm. A P value <.05 was considered statistically significant.

RESULTS

At 3 months postoperatively, 88.3% (242/274) of eyes were available for follow-up. Postoperatively, 91.4% of eyes in the OPDCAT group and 90.6% of eyes in the OATz group were within 0.50 D. No difference in refractive outcomes and patient satisfaction among groups or subgroups was noted (P>.05). A significantly less change in asphericity (less oblate) was noted for the OPDCAT group (0.31 +/- 0.30) compared with the OATz group (0.51 +/- 0.35) (P<.05). A lower induction of aberrations in the OPDCAT group compared with the OATz group was noted ( P<.05). Mesopic contrast sensitivity was significantly higher for the OPDCAT groups and subgroups (P<.05).

CONCLUSIONS

Refractive outcomes between groups or subgroups were equivalent. A significantly lower induction of higher order aberrations and less change in asphericity in the OPDCAT group was noted. The OPDCAT algorithm was more likely to maintain mesopic contrast sensitivity.

Comparison of Collamer toric implantable [corrected] contact lens implantation and wavefront-guided laser in situ keratomileusis for high myopic astigmatism

PURPOSE

To compare the postoperative visual outcomes after implantation of a Collamer toric implantable contact lens (ICL) and after wavefront-guided laser in situ keratomileusis in high myopic astigmatism.

SETTING

Department of Ophthalmology, Kitasato University, Kanagawa, Japan.

METHODS

This study comprised 30 eyes (18 patients) having toric ICL implantation and 24 eyes (17 patients) having wavefront-guided LASIK (Technolas 217z) to correct high myopic astigmatism (manifest spherical equivalent [SE] <or=-6.0 diopters [D]; manifest refractive cylinder >or=1.0 D). The safety, efficacy, predictability, stability, and adverse events were assessed preoperatively and 1 week and 1, 3, and 6 months postoperatively.

RESULTS

At 6 months, the mean safety index was 1.28+/-0.25 (SD) in the ICL group and 1.01+/-0.16 in the LASIK group and the mean efficacy index, 0.87+/-0.15 and 0.83+/-0.23, respectively. All eyes in the ICL group and 71% of eyes in the LASIK group were within +/-1.00 D of the targeted SE correction at 6 months. The mean change in manifest refraction from 1 week to 6 months was -0.04+/-0.24 D in the ICL group and -0.60+/-0.49 D in the LASIK group. There were no significant complications in the ICL group; 2 eyes (8.3%) in the LASIK group required enhancement ablations.

CONCLUSION

Toric ICL implantation was better than wavefront-guided LASIK in eyes with high myopic astigmatism in almost all measures of safety, efficacy, predictability, and stability, suggesting that toric ICL implantation may become a viable surgical option to treat high myopic astigmatism.

Wavefront-guided LASIK for the correction of primary myopia and astigmatism a report by the American Academy of Ophthalmology

OBJECTIVE

To describe wavefront-guided (WFG) LASIK for the primary treatment of low to moderate levels of myopia and astigmatism and to examine the evidence on the safety and effectiveness of the procedure in comparison with conventional LASIK.

METHODS

Literature searches conducted in 2004, 2005, 2006, and 2007 retrieved 209 unique references from the PubMed and Cochrane Library databases. The panel selected 65 articles to review, and of these, chose 45 articles that they considered to be of sufficient clinical relevance to submit to the panel methodologist for review. During the review and preparation of this assessment, an additional 2 articles were included. A level I rating was assigned to properly conducted, well-designed, randomized clinical trials; a level II rating was assigned to well-designed cohort and case-controlled studies; and a level III rating was assigned to case series, case reports, and poorly designed prospective and retrospective studies. In addition, studies that were conducted by laser manufacturers before device approval (premarket approval) were reviewed as a separate category of evidence.

RESULTS

The assessment describes studies reporting results of WFG LASIK clinical trials, comparative trials, or both of WFG and conventional LASIK that were rated level II and level III. There were no studies rated as level I evidence. Four premarket approval studies conducted by 4 laser manufacturers were included in the assessment. The assessment did not compare study results or laser platforms because there were many variables, including the amount of follow-up, the use of different microkeratomes, and the level of preoperative myopia and astigmatism.

CONCLUSIONS

There is substantial level II and level III evidence that WFG LASIK is safe and effective for the correction of primary myopia or primary myopia and astigmatism and that there is a high level of patient satisfaction. Microkeratome and flap-related complications are not common but can occur with WFG LASIK, just as with conventional LASIK. The WFG procedure seems to have similar or better refractive accuracy and uncorrected visual acuity outcomes compared with conventional LASIK. Likewise, there is evidence of improved contrast sensitivity and fewer visual symptoms, such as glare and halos at night, compared with conventional LASIK. Even though the procedure is designed to measure and treat both lower- and higher-order aberrations (HOAs), the latter are generally increased after WFG LASIK. The reasons for the increase in HOA are likely multifactorial, but the increase typically is less than that induced by conventional LASIK. No long-term assessment of WFG LASIK was possible because of the relatively short follow-up (12 months or fewer) of most of the studies reviewed.

Topography-guided Ablation for Treatment of Patients With Irregular Astigmatism

PURPOSE

To evaluate the customized aspheric treatment zone (CATz) topography-guided ablation for the correction of irregular astigmatism induced by initial corneal refractive surgery or corneal injury.

METHODS

CATz ablation was performed on 32 eyes of 28 patients. Each procedure was performed by photorefractive keratectomy (PRK) or LASIK using a NIDEK EC-5000 excimer laser. The eyes had decentered ablations, small optical zones, decreased best spectacle-corrected visual acuity (BSCVA), and asymmetrical astigmatism. Subjective symptoms, uncorrected visual acuity (UCVA), BSCVA, refraction, corneal topography, and higher order aberrations were measured. Mean follow-up was 161.9 +/- 129.9 days (range: 90 to 492 days).

RESULTS

Data obtained at final postoperative follow-up show that UCVA and BSCVA increased by > or = 2 lines after CATz ablation in 17 and 11 eyes and decreased in 4 and 2 eyes, respectively. Higher order aberrations were decreased in 16 eyes and increased in 1 eye. Topographical maps were improved with decreased surface regularity index (20 eyes) and surface asymmetry index (22 eyes). Seven eyes required further enhancement for residual refractive errors. Thirteen patients (15 eyes) claimed they were satisfied with the outcome, 6 patients (7 eyes) stated that the outcome was lower than expected, and 4 patients (4 eyes) stated they were dissatisfied.

CONCLUSIONS

CATz topographic ablation effectively improves the quality of vision and symptoms in the majority of patients with irregular corneal astigmatism from previous excimer laser refractive surgery. However, residual or induced refractive errors may need to be corrected with a second operation after CATz.