Myopic LASIK Outcomes: Comparison of Three Different Femtosecond Lasers and a Mechanical Microkeratome Using the Same Excimer Laser.

INTRODUCTION: To compare the influence of one microkeratome and three femtosecond lasers on myopic laser in situ keratomileusis (LASIK) outcomes. METHODS: Retrospective, observational cohort study. We compared 134 eyes treated with the IntraLase 60 kHz, 112 eyes treated with the Femto LDV Z6, 206 eyes treated with the FS200, and 98 eyes treated with the Hansatome zero compression microkeratome. All eyes were operated on using the same surgical protocol with the same excimer laser (Wavelight Allegretto) and were allocated to refraction-matched groups. RESULTS: One day and one week postoperatively, uncorrected distance visual acuity was significantly lower in the FS200 group compared to others (P = 0.0001). This difference disappeared at the 1- and 3-month postoperative visits. Significant differences were found among groups in terms of safety index (P = 0.0001), residual sphere (P = 0.0001), and residual cylinder (P = 0.02) at the 3-month postoperative visit. No significant differences were found in corrected distance visual acuity or efficacy index. CONCLUSION: According to our results, a slight delay in visual restoration after FS200 LASIK surgery might be expected. This delay was statistically significant at 1 day and 1 week postoperatively, but there were no differences from the 1-month visit onwards. Additionally, significant differences were found among devices in terms of safety index and the refractive results, which were found not to be clinically relevant.

Effect of Laser-assisted Subepithelial Keratectomy with Mitomycin C on Corneal Optical Density Measured with Confocal Microscopy.

SIGNIFICANCE: The development of confocal microscopy allows one to obtain high-resolution corneal images like its optical density. Some studies have evaluated the optical density with Scheimpflug cameras in the early post-operative period after photorefractive keratectomy, but no studies have evaluated the long-term evolution of optical density after surface ablation when mitomycin C is used. PURPOSE: This work aimed to study the changes in corneal optical density measured with confocal microscopy in eyes treated with laser-assisted subepithelial keratectomy (LASEK) and intraoperative mitomycin C (MMC) to correct myopia. METHODS: A study of 24 consecutive myopic eyes that underwent LASEK with 0.02% MMC and a control group of 24 healthy nontreated eyes was performed. Optical density was measured using the images by the confocal microscopy of the Heidelberg Retina Tomograph II with the Rostock Cornea Module. An analysis of confocal microscopy images was performed using the ImageJ software to obtain the optical density, in gray-scale units (GSU). The optical density of the stromal bed was evaluated 3 months, 15 months, and 3 years after surgery and was compared with the optical density at the equivalent depth of the stroma in controls. RESULTS: The mean values of optical density for the LASEK group were 81.7 ± 9.7, 78.6 ± 11.7, and 73.6 ± 18.7 GSU at 3 months, 15 months, and 3 years, respectively, and it was 61.8 ± 8.2 GSU for the control group. A statistically higher optical density 3 and 15 months after LASEK with MMC was found compared with controls (P < .001). No significant difference was found in optical density at 3 years post-operatively. CONCLUSIONS: Our study suggests that, after LASEK with MMC, the anterior corneal stroma has a higher optical density at 3 and 15 months post-operatively, which gradually returns to normal values 3 years after surgery.

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.

Effect of age on visual and refractive results after laser-assisted subepithelial keratomileusis (LASEK) with adjuvant use of mitomycin C / Efecto de la edad en los resultados visuales y refractivos después de la queratomileusis subepitelial asistida por láser (LASEK) con el uso adyuvante de mitomicina C

Purpose: To evaluate the influence of age on visual and refractive results after laser-assisted subepithelial keratomileusis (LASEK) with the adjuvant use of mitomycin C (MMC) for the correction of myopia. Methods: Retrospective, nonrandomized, cohort study. A total of 1374 eyes treated with LASEK+MMC were included in the study (we compared 1163 eyes of patients aged 18 to 40 years versus 211 eyes of patients over 40 years). Visual and refractive results were evaluated at the 6-month postoperative visit. Results: Six months postoperatively, both the uncorrected distance visual acuity and the corrected distance visual acuity were significantly better in the group of young patients ( P= 0.0001). We found a slight tendency to overcorrection in the group of young patients compared to a slight tendency to undercorrection in the group of patients over 40 years (P = 0.002). The efficacy index was significantly better in the group of younger patients (0.91 ± 0.2) than in the older patients (0.86±0.2) (P = 0.0001). No significant difference was found in the safety index between groups. 81.5% of eyes in the group of patients aged 18 to 40 years compared to 75.3% of eyes in the group of patients aged >40 years were within ± 0.5D of emmetropia ( P= 0.001). Conclusions: A tendency toward undercorrection and less predictability was found with aging after myopic LASEK with MMC for the correction of myopia

Objetivo: Evaluar la influencia de la edad sobre los resultados visuales y refractivos tras queratomileusis subepitelial asistida por láser (LASEK) con uso adyuvante de mitomicina C (MMC) para la corrección de la miopía. Métodos: Estudio de cohorte retrospectivo y no aleatorizado. Se incluyó en el estudio a un total de 1.374 ojos tratados con LASEK + MMC (comparamos 1.163 ojos de pacientes de edades comprendidas entre 18 y 40 años, con 211 ojos de pacientes mayores de 40 años). Los resultados visuales y refractivos se evaluaron durante la visita postoperatoria transcurridos 6 meses. Resultados: A los seis meses de la intervención, tanto la agudeza visual de lejos no corregida como corregida fueron mejores en el grupo de pacientes jóvenes (P = 0,0001). Encontramos una ligera tendencia hacia la sobre-corrección en el grupo de pacientes jóvenes, en comparación a una ligera tendencia hacia la infra-corrección en el grupo de pacientes mayores de 40 años (P = 0,002). El índice de eficacia fue significativamente mejor en el grupo de pacientes jóvenes (0,91 ± 0,2) que en el de pacientes mayores (0,86 ± 0,2) (P = 0,0001). No se encontró diferencia significativa en cuanto al índice de seguridad entre grupos. El 81,5% de los ojos del grupo de pacientes con edades comprendidas entre 18 y 40, en comparación con el 75,3% de los ojos en el grupo de pacientes mayores de >40 años, reflejó un valor±0,5D de emetropía (P = 0,001). Conclusiones: Se encontró una tendencia hacia la infra-corrección y menor predecibilidad con la edad tras la realización de LASEK con MMC para la corrección de la miopía

Long-term corneal subbasal nerve plexus regeneration after laser in situ keratomileusis.

PURPOSE: To analyze the recovery of the subbasal nerve plexus in corneas treated with laser in situ keratomileusis (LASIK) at least 10 years prior compared with nonoperated corneas. SETTING: Clínica Novovisión, Madrid, Spain. DESIGN: Prospective nonrandomized observational study. METHODS: Eyes that had LASIK surgery at least 10 years before (LASIK group) were compared with nonoperated healthy eyes (control group). The subbasal nerve plexus morphology (main nerves density, nerve length, nerve branches density, grade of nerve tortuosity, and reflectivity) and the dendritic cell density from the confocal images obtained with the Heidelberg Retina Tomograph II were analyzed. RESULTS: The study comprised 47 eyes (27 eyes in the LASIK group and 20 eyes in the control group). The values were significantly lower in the LASIK group compared with the control group in main nerves density (9.15 nerves/mm2 ± 3.46 [SD] versus 11.75 ± 2.86 nerves/mm2; P = .009) and nerve branches density (2.96 ± 1.99 nerves/mm2 versus 5.35 ± 3.05 nerves/mm2; P = .002). No significant differences were found in nerve length, grade of nerve tortuosity, dendritic cell density, or subbasal nerve plexus reflectivity between the two groups. CONCLUSIONS: The outcomes suggested that the subbasal corneal nerve plexus did not completely recover its preoperative pattern at least 10 years after LASIK. Both main nerves density and nerve branches density continued to be significantly lower compared with virgin corneas after a mean 13-year follow-up, although other parameters of nerve morphology (nerve length, tortuosity, and reflectivity) returned to normal levels.

Effect of age on visual and refractive results after laser-assisted subepithelial keratomileusis (LASEK) with adjuvant use of mitomycin C.

PURPOSE: To evaluate the influence of age on visual and refractive results after laser-assisted subepithelial keratomileusis (LASEK) with the adjuvant use of mitomycin C (MMC) for the correction of myopia. METHODS: Retrospective, nonrandomized, cohort study. A total of 1374 eyes treated with LASEK+MMC were included in the study (we compared 1163 eyes of patients aged 18 to 40 years versus 211 eyes of patients over 40 years). Visual and refractive results were evaluated at the 6-month postoperative visit. RESULTS: Six months postoperatively, both the uncorrected distance visual acuity and the corrected distance visual acuity were significantly better in the group of young patients (P=0.0001). We found a slight tendency to overcorrection in the group of young patients compared to a slight tendency to undercorrection in the group of patients over 40 years (P=0.002). The efficacy index was significantly better in the group of younger patients (0.91±0.2) than in the older patients (0.86±0.2) (P=0.0001). No significant difference was found in the safety index between groups. 81.5% of eyes in the group of patients aged 18 to 40 years compared to 75.3% of eyes in the group of patients aged >40 years were within±0.5D of emmetropia (P=0.001). CONCLUSIONS: A tendency toward undercorrection and less predictability was found with aging after myopic LASEK with MMC for the correction of myopia.

Effect of age on visual and refractive results after LASIK: mechanical microkeratome versus femtosecond laser.

AIM: To evaluate the effect of age on visual and refractive results after laser in situ keratomileusis (LASIK) obtained with a mechanical microkeratome or a femtosecond laser. METHODS: Retrospective, nonrandomized, cohort study. A total of 3826 eyes were included in the study (1725 eyes treated with mechanical LASIK and 2101 eyes treated with femtosecond LASIK). The relationship between patient age and the 3-month postoperative visual and refractive results of both procedures were analyzed by linear regression analysis. RESULTS: Three months postoperatively, we found a significant correlation between age and the postoperative spherical equivalent (SE; r 2=0.004, P=0.006), efficacy (r 2=0.006, P=0.001), and safety indexes (r 2=0.05, P=0.0001) in the mechanical LASIK group. On the other hand, we found a significant correlation between age and the postoperative SE (r 2=0.02, P=0.0001) and the efficacy index (r 2=0.01, P=0.0001) but not the safety index in the femtosecond laser group. Mechanical LASIK provided slightly but significantly better efficacy and predictability in patients 18 to 40 years of age and femtosecond LASIK did so in patients older than 40 years of age. The femtosecond laser provided better safety results than the mechanical microkeratome in both age groups. CONCLUSION: A tendency toward undercorrection and less predictability is found with aging after myopic LASIK regardless of whether the flap was created with a mechanical microkeratome or a femtosecond laser. However, femtosecond laser provides significantly better outcomes in terms of efficacy, safety and predictability compared to mechanical microkeratome for the correction of myopia in patients over 40y.

Retinal nerve fiber layer thickness after laser-assisted subepithelial keratomileusis and femtosecond LASIK: a prospective observational cohort study.

PURPOSE: Based on the assumption that high levels of intraocular pressure (IOP) during femtosecond laser-assisted in situ keratomileusis (FS-LASIK) may compromise the retinal nerve fiber layer (RNFL), newer femtosecond platforms that operate without causing significant IOP elevation have been developed in recent years. However, this assumption has not been adequately tested. The aim of the current study was to evaluate possible changes in RFNL thickness in nonglaucomatous myopic patients undergoing FS-LASIK using the 60 KHz IntraLase® device that significantly elevates the IOP for an appreciable period of time vs an advanced surface ablation technique (laser-assisted subepithelial keratomileusis, LASEK) that does not induce any IOP elevation. METHODS: This was a prospective, observational, controlled cohort study. One randomly selected eye of 114 consecutive eligible patients was analyzed. Inclusion criteria were myopia up to -6.00 diopters and astigmatism up to -2.00 diopters. As clinically indicated, 50 patients underwent LASEK and 64 underwent FS-LASIK. The RNFL thickness was determined with a spectral-domain optical coherence tomography device preoperatively and 3 months postoperatively by the same masked observer. RESULTS: There was no significant difference in preoperative refractive error, age, or sex between the groups. Preoperatively, central corneal thickness was significantly lower in the LASEK group (529.1±36.1 vs 562.4±31.6 µm, P=0.001). For the LASEK group, there was no significant difference between preoperative and postoperative RNFL thickness in the studied sectors (superior-temporal, temporal, inferior-temporal, average). For the FS-LASIK group, compared to preoperative RNFL measures, statistically significant thicker postoperative values were found for the average RNFL (mean difference: 0.67 µm, 0.7% increase, P=0.008) and the inferior-temporal sector (mean difference: 0.92 µm, 0.6% increase, P=0.02). CONCLUSION: LASIK with a femtosecond platform that induces high intraoperative IOP did not cause RNFL thinning. The observed differences between preoperative and postoperative values are below the axial resolution limit of optical coherence tomography devices.

Long-term Follow-up of LASEK With Mitomycin C Performed to Correct Myopia in Thin Corneas.

PURPOSE: To evaluate the long-term outcomes of laser-assisted subepithelial keratomileusis (LASEK) with intraoperative use of mitomycin C (MMC) performed on thin corneas for the correction of myopia. METHODS: This retrospective cohort study included 100 eyes with a preoperative central corneal thickness (CCT) thinner than 500 µm that underwent LASEK + MMC with at least 6 years of follow-up. Stability of visual acuity and refraction and the efficacy, safety, and predictability at the examinations 3 months and the last annual postoperative visit were analyzed. RESULTS: Preoperative CCT was 482.9 ± 14.7 µm (range: 433 to 499 µm). Mean preoperative spherical equivalent was -4.09 ± 2.3 diopters (D). At the 3-month postoperative visit, mean CCT was 419.79 ± 32.6 µm. The residual spherical equivalent showed a statistically significant regression (P = .001) in the comparison between the 3-month and the last annual postoperative visit. The efficacy index showed a significant decrease (P = .01) and the safety index remained stable around 0.96. Six or more years after the surgery, 85 eyes (85%) were within ±0.50 D and 94 eyes (94%) eyes were within ±1.00 D of emmetropia. The topography did not show signs of secondary corneal ectasia in any eye. CONCLUSIONS: LASEK with intraoperative use of MMC seems to be safe, effective, and predictable to correct myopia in corneas thinner than 500 µm and with normal preoperative topography, providing good visual and refractive outcomes with no topographic signs of corneal ectasia in a mean 6.5-year follow-up. [J Refract Surg. 2017;33(12):813-819.].