Wavefront-guided PRK treatment of myopia using a refractive aberrometer

PURPOSE

To evaluate the safety, effectiveness, and patient-reported outcomes of wavefront-guided photorefractive keratectomy (PRK) for the correction of myopic refractive errors with and without astigmatism.

SETTING

U.S. multicenter study.

DESIGN

Prospective, nonrandomized clinical investigation.

METHODS

334 eyes (167 patients) underwent wavefront-guided PRK with the STAR S4 IR Excimer Laser System. Patients had preoperative myopic refractive errors with sphere up to -8.00 diopters (D) and cylinder up to -4.00 D with a maximum spherical equivalent (SE) of -10.00 D. All eyes were targeted for emmetropia, and treatment plans were derived from the iDESIGN system wavefront measurements.

RESULTS

At 6 months, the point of refractive stability, 99.4% of eyes achieved 20/20 or better uncorrected distance visual acuity (UDVA), 92% of eyes achieved 20/16 or better UDVA, 85.5% of eyes achieved manifest refraction SE (MRSE) within 0.50 D of target, mean SE was -0.06, and less than 1% of eyes lost more than 2 lines of corrected distance visual acuity. Glare and halos occurred with similar or lower frequencies at 6 months vs preoperative. Results from the National Eye Institute Refractive Error Quality of life questionnaire showed statistically significant improvements at 6 months vs preoperative across most measures of vision-related functioning and well-being. Approximately 98% of patients reported high satisfaction with their overall vision at 6 months.

CONCLUSIONS

Wavefront-guided PRK with the iDESIGN aberrometer was safe, effective, and predictable for the correction of low to moderate myopia with and without astigmatism and led to high patient satisfaction.

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.

Wavefront-Guided Photorefractive Keratectomy with the Use of a New Hartmann-Shack Aberrometer in Patients with Myopia and Compound Myopic Astigmatism

Purpose. To assess refractive and visual outcomes and patient satisfaction of wavefront-guided photorefractive keratectomy (PRK) in eyes with myopia and compound myopic astigmatism, with the ablation profile derived from a new Hartmann-Shack aberrometer. Methods. In this retrospective study, 662 eyes that underwent wavefront-guided PRK with a treatment profile derived from a new generation Hartmann-Shack aberrometer (iDesign aberrometer, Abbott Medical Optics, Inc., Santa Ana, CA) were analyzed. The preoperative manifest sphere ranged from −0.25 to −10.75 D, and preoperative manifest cylinder was between 0.00 and −5.25 D. Refractive and visual outcomes, vector analysis of the change in refractive cylinder, and patient satisfaction were evaluated. Results. At 3 months, 91.1% of eyes had manifest spherical equivalent within 0.50 D. The percentage of eyes achieving uncorrected distance visual acuity 20/20 or better was 89.4% monocularly and 96.5% binocularly. The mean correction ratio of refractive cylinder was 1.02 ± 0.43, and the mean error of angle was 0.00 ± 14.86° at 3 months postoperatively. Self-reported scores for optical side effects, such as starburst, glare, halo, ghosting, and double vision, were low. Conclusion. The use of a new Hartmann-Shack aberrometer for wavefront-guided photorefractive keratectomy resulted in high predictability, efficacy, and patient satisfaction.

Four-year visual outcomes after photorefractive keratectomy in pilots with low-moderate myopia

BACKGROUND

The photorefractive keratectomy (PRK) is approved for Air Force pilots in several nations. The occupational environments of pilots in the Air Force are unique, including extremely high altitude, low oxygen tension, high ultraviolet light exposure and high G-force load. The short-term efficacy and safety of PRK for pilots are documented. However, the study for long-term visual and refractive outcomes of PRK in pilots is limited.

OBJECTIVE

To investigate the long-term visual and refractive outcomes in a 4-year follow-up period after PRK in pilots with low to moderate myopia.

METHODS

Thirty-eight eyes of 20 subjects that underwent PRK and recruited to Air Force pilot were evaluated preoperatively and at 3, 6, 12, 24, and 48 months postoperatively.

RESULTS

The mean patient age was 21.42±0.75 years. The mean preoperative manifest refraction spherical equivalent (SE) was -1.51±1.15 diopters (D). At 4 years postoperatively, the mean SE was -0.29±0.51, 89.5% of eyes achieved 20/20 or better Snellen uncorrected visual acuity, 71.1% of eyes were within ±0.50 D of emmetropia. The refraction stabilised by 6 months and was maintained up to the 4-year follow-up stage.

CONCLUSIONS

PRK for pilots with low to moderate myopia is safe and effective in the long term. High-altitude environmental stress exposure has no effect on the refractive stability after PRK.

TRIAL REGISTRATION NUMBER

ROKAF-ASMC-2015-IRB-002.

Prospective randomized contralateral eye evaluation of subjective quality of vision after wavefront-guided or wavefront- optimized photorefractive keratectomy

PURPOSE

To compare the effect of wavefront-guided (WFG) and wavefront-optimized (WFO) photorefractive keratectomy (PRK) on patient perceived quality of vision.

METHODS

Seventy-one patients (142 eyes) were enrolled in this prospective, randomized, fellow eye controlled study. One eye was randomized to undergo WFG PRK treatment by the AMO Visx CustomVue S4 IR excimer laser system (Abbott Medical Optics, Inc., Santa Clara, CA) and the fellow eye received WFO PRK treatment by the Alcon Allegretto Wave Eye-Q 400 Hz excimer laser system (Alcon Laboratories, Inc., Fort Worth, TX). Patients answered questionnaires on their visual symptoms and quality of vision preoperatively and at 1, 3, 6, and 12 months after surgery.

RESULTS

Patients in both groups reported better vision compared to baseline from 3 months onward (mean change in score of 1.56 to 2.51 in the WFO group and 1.54 to 2.28 in the WFG group, P ⩽ .003). Both groups experienced less nighttime glare from 6 months onward (P ⩽ .030). Halos, double vision, and visual clarity were initially worse (P ⩽ .025) but not significantly different after 1 month. Haze and fluctuating vision resolved after 3 months. Visual symptoms were similar between the two groups at all times (P ⩾ .059) except at 6 months, when patients felt their WFG eyes had more excellent vision (P = .029). A composite of all symptoms was also similar between the groups until 12 months when patients had fewer symptoms in their WFO eye (P = .044).

CONCLUSIONS

One year after surgery, patient self-reported visual symptoms were not significantly different in eyes receiving WFG or WFO PRK. However, the average of all symptoms was lower in eyes receiving wavefront-optimized treatment.

Four-year visual, refractive, and contrast sensitivity outcomes after wavefront-guided myopic LASIK using an advanced excimer laser platform

PURPOSE

To evaluate the 4-year visual, refractive, and contrast sensitivity outcomes of wavefront-guided LASIK for the correction of low to moderate myopia using the VISX CustomVue technology (Abbott Medical Optics, Inc., Santa Ana, CA).

METHODS

This was a prospective study including 255 consecutive eyes of 145 patients (age range: 19 to 55 years) with low to moderate myopia (mean spherical equivalent: -3.36 ± 1.71 diopters [D]) undergoing laser refractive surgery. Wavefront-guided LASIK was performed in all eyes using the VISX STAR S4 IR excimer laser platform and the CustomVue procedure for the ablation profile design. Visual, refractive, and contrast sensitivity changes were evaluated during a 4-year follow-up period.

RESULTS

Postoperative logMAR uncorrected distance visual acuity was 0.1 or better (20/25 Snellen) in 98.0% and 100% of eyes at 1 and 4 years, respectively. At 4 years postoperatively, mean spherical equivalent was reduced significantly to a mean value of -0.22 ± 0.28 D (P < .01), with 97.3% of eyes with a spherical equivalent within ±0.50 D. The astigmatic power vector component J0 of manifest refraction was also reduced significantly (P < .01). Postoperative logMAR corrected distance visual acuity was 0.0 or better (20/20 Snellen) in 96.1% and 98.8% of eyes at 1 and 4 years, respectively. Improvement in contrast sensitivity was observed in some spatial frequencies between 1 and 4 years postoperatively. No significant correlations were found between 4-year contrast sensitivity and corrected distance visual acuity (0.024 ≤ r ≤ -0.120, P ≥ .06).

CONCLUSION

Wavefront-guided LASIK using the VISX CustomVue technology provides an effective and predictable correction of low to moderate myopia in the long term, preserving the patient's visual acuity and quality.

Prospective, randomized, fellow eye comparison of WaveLight Allegretto Wave Eye-Q versus VISX CustomVueTM STAR S4 IRTM in photorefractive keratectomy: analysis of visual outcomes and higher-order aberrations

Background

The purpose of this study was to compare differences in visual outcomes, higher-order aberrations, contrast sensitivity, and dry eye in patients undergoing photorefractive keratectomy using wavefront-guided VISX CustomVue™ and wavefront-optimized WaveLight^® Allegretto platforms.

Methods

In this randomized, prospective, single-masked, fellow-eye study, photorefractive keratectomy was performed on 46 eyes from 23 patients, with one eye randomized to WaveLight Allegretto, and the fellow eye receiving VISX CustomVue. Three-month postoperative outcome measures included uncorrected distance visual acuity, corrected distance visual acuity, refractive error, root mean square of total and grouped higher-order aberrations, contrast sensitivity, and Schirmer’s testing.

Results

Mean values for uncorrected distance visual acuity (logMAR) were −0.03 ± 0.07 and −0.06 ± 0.09 in the wavefront-optimized and wavefront-guided groups, respectively (P = 0.121). Uncorrected distance visual acuity of 20/20 or better was achieved in 91% of eyes receiving wavefront-guided photorefractive keratectomy, and 87% of eyes receiving wavefront-optimized photorefractive keratectomy, whereas uncorrected distance visual acuity of 20/15 was achieved in 35% of the wavefront-optimized group and 64% of the wavefront-guided group (P ≥ 0.296). While root mean square of total higher-order aberration, coma, and trefoil tended to increase in the wavefront-optimized group (P = 0.091, P = 0.115, P = 0.459, respectively), only spherical aberration increased significantly (P = 0.014). Similar increases were found in wavefront- guided root mean square of total higher-order aberration (P = 0.113), coma (P = 0.403), trefoil (P = 0.603), and spherical aberration (P = 0.014). There was no significant difference in spherical aberration change when comparing the two platforms. The wavefront-guided group showed an increase in contrast sensitivity at 12 cycles per degree (P = 0.013).

Conclusion

Both VISX CustomVue and WaveLight Allegretto platforms performed equally in terms of visual acuity, safety, and predictability in photorefractive keratectomy. The wavefront-guided group showed slightly improved contrast sensitivity. Both lasers induced a comparable degree of statistically significant spherical aberration, and tended to increase other higher-order aberration measures as well.