Flaporhexis: Rapid and effective technique to limit epithelial ingrowth after LASIK enhancement

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.

Effect of Time Since Primary Laser-Assisted In Situ Keratomileusis on Flap Relift Success and Epithelial Ingrowth Risk

PURPOSE

To assess the association of time since primary laser-assisted in situ keratomileusis with flap relift success and risk of epithelial ingrowth in eyes undergoing flap relift after primary laser-assisted in situ keratomileusis.

SETTING

Hong Kong Sanatorium & Hospital, Hong Kong Special Administrative Region.

DESIGN

Retrospective, observational case series.

METHODS

Seventy-three eyes with flaps relifted for refractive enhancement laser-assisted in situ keratomileusis were included. Main outcome measures included rate of relift success and epithelial ingrowth; associations of time since primary laser-assisted in situ keratomileusis, sex, age at relift, year of relift, and flap creation method in primary laser-assisted in situ keratomileusis with relift success and epithelial ingrowth.

RESULTS

Relifting was successful in 71 eyes (97.3%). Among the successfully relifted eyes, 12 (16.9%) developed epithelial ingrowth, of which 3 (4.2%) were clinically significant. No eyes lost more than one line of corrected distance visual acuity. The time since primary laser-assisted in situ keratomileusis (up to 22 years), sex, age at relift, year of relift, and flap creation method in primary laser-assisted in situ keratomileusis were not associated with relift success or epithelial ingrowth.

CONCLUSIONS

With our described surgical technique, flaps could be successfully relifted without much difficulty up to 22 years after primary laser-assisted in situ keratomileusis with a low incidence of epithelial ingrowth.

Re-Treatment by Flap Relift Versus Surface Ablation After Myopic Laser In Situ Keratomileusis

PURPOSE

To compare clinical outcomes of patients undergoing first re-treatment by flap relift with those re-treated by surface ablation on the flap after an initial myopic laser-assisted in situ keratomileusis (LASIK) procedure.

METHODS

This is a retrospective cohort analysis of consecutive patients who underwent myopic LASIK and required re-treatment between January 2007 and December 2016. Cases re-treated by flap relift were propensity score matched with cases re-treated by surface ablation, and clinical outcomes were compared. One eye from each patient was included.

RESULTS

A total of 1,234 out of 21,191 cases required re-treatment after myopic LASIK during the follow-up period. Surface ablation was performed in 75% of cases and relift in 25%. Patients re-treated by surface ablation were more commonly male (61.8% vs. 48.1%, P < 0.001), were younger (33.2 ± 7.8 vs. 35.2 ± 10 years, P = 0.005), and had thinner corneas (483 ± 46 vs. 502 ± 43 μm, P < 0.001). Propensity score matching was performed for 416 eyes (208 from each group). After matching, differences in baseline characteristics became nonsignificant (P > 0.05). Cases re-treated by surface ablation had a worse safety index (0.98 ± 0.12 vs. 1.02 ± 0.17, P = 0.049), yet better predictability (0.14 ± 0.6 vs. 0.35 ± 0.5 diopters of deviation, P = 0.009), a similar efficacy index (0.92 ± 0.2 vs. 0.93 ± 0.3, P = 0.814), higher rates of haze (5.8% vs. 0.5%, P = 0.002), and a lower risk for epithelial ingrowth (0.5% vs. 8.2%, P < 0.001).

CONCLUSIONS

Re-treatment after myopic LASIK with surface ablation resulted in worse safety and higher rates of haze, yet more predictable outcomes and reduced ingrowth rates, compared with re-treatment with flap relift.

Microkeratome versus femtosecond flaps: accuracy and complications

PURPOSE OF REVIEW

To update the knowledge on differences between mechanical microkeratome and femtosecond flaps for laser in-situ keratomileusis (LASIK) in terms of accuracy and complications.

RECENT FINDINGS

Corneal flaps created with the femtosecond laser present a more planar architecture and provide greater precision in flap diameter and thickness; a more uniform flap thickness across the flap diameter and it allows the surgeon to programme the angulation of the flap periphery. Femtosecond LASIK flaps are classically related to complications derived from a more intense inflammatory response, such as diffuse lamellar keratitis and transient light-sensitivity syndrome. Newer femtosecond models allow for much lower energy delivery to cut the flap, to the point the overall inflammatory response is not significantly different from the microkeratome. The incidence of complications such as epithelial defect and flap dislocations is higher with microkeratome flaps.

SUMMARY

This review examines the accuracy and complications of flaps created with femtosecond and microkeratome. Both femtosecond and microkeratome are able to create accurate LASIK flaps. Femtosecond LASIK flaps represent significant improvement in morphology and predictability with implications for safety.

Management of residual refractive error after laser in situ keratomileusis and photorefractive keratectomy

PURPOSE OF REVIEW

To review the various steps and methods in managing residual refractive error after laser in situ keratomileusis and photorefractive keratectomy (PRK).

RECENT FINDINGS

Past studies have shown the efficacy and safety of flap relifts over recuts and for surface ablation over the flap. Other previous and also more recent studies show the use of a femtosecond laser for side cuts only. Recently, the creation of a femtosecond mini flap has been described. New studies also demonstrate the use of collagen cross-linking in postrefractive surgery ectasia.

SUMMARY

Residual refractive error is a known complication after both laser in situ keratomileusis and PRK. A systematic approach should be taken to manage this complication starting with a thorough evaluation to determine if an enhancement is indicated and if so, which method will be the safest and most efficacious for the patient.

Creation of a new femtosecond laser-assisted mini-flap to enhance late regression after LASIK

PURPOSE

To describe a method of LASIK enhancement in which a new femtosecond laser-assisted mini-flap is created over the original LASIK flap.

METHODS

The 60-kHz IntraLase femtosecond laser (IntraLase Corp., Irvine, CA) was used to create a new mini-flap over an original LASIK flap for the re-treatment of late regression after LASIK. The diameter of the mini-flap was 7 mm and the attempted flap depth was 100 μm.

RESULTS

The procedure was performed on 10 eyes of 7 patients. No intraoperative or postoperative complications developed in any case during the follow-up. At the 6-month follow-up visit, all eyes were within ±0.5 diopters of the targeted refraction.

CONCLUSIONS

The preliminary results suggest that creation of a femtosecond laser-assisted mini-flap over a previous LASIK flap seems to be a safe and effective procedure for the enhancement of late regression after LASIK. By creating a femtosecond laser-assisted mini-flap that is smaller in diameter than the original flap, the adhesion of the primary flap edges and peripheral interface remain intact, thus decreasing the risk of dislocation of the original LASIK flap and of losing a sliver of tissue.