A Prospective Comparison of Wavefront-Guided LASIK versus Wavefront-Guided PRK After Previous Keratorefractive Surgery

[Enhancement Options after Lens and Corneal Refractive Surgery]

BACKGROUND

 Modern preoperative diagnostics as well as current surgical techniques allow cataract and refractive surgery to deliver precise refractive results.Occasionally, unsatisfactory refractive and visual results occur despite all the care taken. In these cases, subsequent improvement is required to achieve the best final visual outcome. This article shows the therapeutic options for the treatment of residual refractive errors after lens and corneal refractive surgery.

KEY MESSAGES

 The causes of postoperative refractive errors after refractive laser- or lens-based procedures are very diverse and require extensive workup of the cause as well as an individual solution to achieve the desired result. Before any further surgical intervention, specific complications of the primary procedure as well as concomitant ocular diseases must be excluded or treated. The appropriate enhancement after keratorefractive surgery depends primarily on the type of primary surgery, residual stromal thickness, possible complications from the initial surgery, and the patient's personal preference. For enhancements using surface treatments, such as PRK, the use of mitomycin C is recommended for prophylaxis of haze formation. After lens surgery, for low-grade postoperative refractive errors (spherical and astigmatic), keratorefractive enhancements provide the most accurate results. For higher refractive errors, lens-based procedures can be used, with add-on IOLs being safer and more precise compared with one IOL exchange. Low astigmatisms can be successfully treated with LRI or keratorefractive surgery, but higher astigmatisms should be corrected with an IOL exchange in the early postoperative period and with an add-on IOL in the later postoperative period. IOL explantations should be performed very cautiously, especially in cases of pronounced capsular fibrosis, previous posterior capsulotomy, and existing weakness of the zonular apparatus.

Enhancement-Optionen nach Linsen- und refraktiver Hornhautchirurgie

Gelegentlich kommt es trotz aller Sorgfalt und präziser Operationstechnik in der Katarakt- und Refraktivchirurgie zu unbefriedigenden refraktiven und visuellen Ergebnissen. In diesen Fällen ist eine nachträgliche Korrektur erforderlich, um das beste endgültige visuelle Ergebnis zu erzielen. Dieser Beitrag zeigt die Möglichkeiten zur Behandlung residualer Refraktionsfehler nach Linsen- und refraktiver Hornhautchirurgie auf.

Laser-Assisted In Situ Keratomileusis (LASIK) Enhancement for Residual Refractive Error after Primary LASIK

Background: To evaluate the safety, efficacy, and predictability of laser-assisted in situ keratomileusis (LASIK) enhancement after primary LASIK and compare to Food and Drug Administration (FDA) criteria. Methods: Patients who underwent LASIK enhancement after primary LASIK between 2002 and 2019 were compared to those who underwent LASIK without retreatment. Patient demographics, preoperative characteristics, visual outcomes, and postoperative complications were compared between groups. Epithelial ingrowth (EI) development was stratified based on duration between primary and secondary procedures. Results: We compared 901 eyes with LASIK enhancement to 1127 eyes without retreatment. Age, sex, surgical eye, sphere, cylinder, and spherical equivalent (SE) were significantly different between groups (p < 0.05). At 12 months post-enhancement, 86% of the eyes had an uncorrected distance visual acuity of 20/20 or better and 93% of eyes were within ±0.50 D of the target. Development of EI (6.1%) demonstrated an odds ratio of 16.3 in the long-term compared to the short-term (95% CI: 5.9 to 45.18; p < 0.0001). Conclusions: Older age at primary LASIK, female sex, right eye, and larger sphere, cylinder and SE were risk factors for enhancement. Risk of EI significantly increased when duration between primary and enhancement procedures exceeded five years. LASIK enhancements produce favorable outcomes and meet FDA benchmarks for safety, efficacy, and predictability.

Femtosecond LASIK Retreatments After Primary Myopic Photorefractive Keratectomy (Femtosecond LASIK Retreatments of PRK)

PURPOSE

The purpose of the study was to evaluate the results and complications of laser-assisted in situ keratomileusis (LASIK) using a femtosecond laser as a retreatment modality of myopia and myopic astigmatism after previous myopic photorefractive keratectomy (PRK).

METHODS

In this retrospective, consecutive, noncomparative case series study, 69 eyes of 41 patients receiving femtosecond LASIK after previous myopic PRK were evaluated. The mean age was 43.0 ± 8.9 years. The preoperative mean SE was -1.82 ± 1.01 diopter (D), range -0.62 to -6.25. The mean central epithelial thickness was 65 ± 5 μm. A flap was created using a low-energy femtosecond laser (Ziemer LDV Z8), with a programmed thickness calculated by adding 40 μm to the epithelial thickness. Refractive ablation was performed using a Technolas Teneo 317 laser (Bausch and Lomb).

RESULTS

Twelve months after LASIK, the mean SE was -0.03 ± 0.17 D, with all eyes ≤0.50 D of SE. The mean DE was 0.30 ± 0.25, with 62 eyes (89.9%) ≤0.50 D and all eyes ≤1 D. The mean corrected distance visual acuity (CDVA) was 0.04 ± 0.10 logMAR; no eye lost more than 1 line of CDVA. The mean uncorrected distance visual acuity was 0.07 ± 0.13 logMAR, being 20/25 or better in all eyes. The safety index (postoperative CDVA/preoperative CDVA) was 1.05. The efficacy index (postoperative uncorrected distance visual acuity/preoperative CDVA) was 0.98. No significant complications occurred.

CONCLUSIONS

Myopic retreatments by femtosecond LASIK after primary PRK yielded excellent refractive results without relevant complications. The flap thickness must be tailored to the epithelial thickening after PRK.

Intra-Operative Discomfort in Photorefractive Keratectomy

Purpose

Photorefractive keratectomy (PRK) remains a viable, safe, and efficacious option for patients wishing to correct refractive errors. One of its most significant drawbacks is pain. While post-operative pain has been well studied with different management options, intra-operative pain has been less well defined. The purpose of this study was to characterize intra-operative pain during PRK in regard to eye operated on, gender, excimer platform used, surgeon, and age.

Patients and Methods

A total of 134 patients (264 eyes) were prospectively randomized to undergo bilateral PRK of either the right eye first or the left eye first followed immediately by the fellow eye. In the immediate post-operative period they were surveyed using an 11-point Numeric Rating Scale regarding intra-operative pain or discomfort experienced in each eye. Resultant pain scores were then analyzed via two sample z-test and analysis of variance (ANOVA) to characterize pain overall as well as comparing first versus second eye operated on, right versus left eye, male versus female, excimer platform used, inter-surgeon variability, and age.

Results

Of 264 eyes surveyed the mean pain experienced on a 0–10 pain scale was 1.13 (minimal discomfort). There was no statistically significant difference in pain or discomfort when comparing first versus second eye operated on, right versus left eye, male versus female, excimer platform used, operating surgeon, or age.

Conclusion

Intra-operative pain or discomfort experienced by patients is minimal. The absence of statistically significant differences in pain scores studied implies that standard of care procedures achieve adequate analgesia in PRK.