Changes in central corneal thickness and refractive error after thin-flap laser in situ keratomileusis in Chinese eyes

Abstract Purpose To investigate the predictive factors of postoperative myopic regression among subjects who have undergone laser-assisted subepithelial keratomileusis (LASEK), laser-assisted in situ keratomileusis (LASIK) flap created with a mechanical microkeratome (MM), and LASIK flap created with a femtosecond laser (FS). All recruited patients had a manifest spherical equivalence (SE) from − 6.0D to − 10.0D myopia. Methods This retrospective, observational case series study analyzed outcomes of refraction at 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Predictors affecting myopic regression and other covariates were estimated with the Cox proportional hazards model for the three types of surgeries. Results The study enrolled 496 eyes in the LASEK group, 1054 eyes in the FS-LASIK group, and 910 eyes in the MM-LASIK group. At 12 months, from − 6.0D to − 10.0D myopia showed that the survival rates (no myopic regression) were 52.19%, 59.12%, and 58.79% in the MM-LASIK, FS-LASIK, and LASEK groups, respectively. Risk factors for myopic regression included thicker postoperative central corneal thickness (P ≦ 0.01), older age (P ≦ 0.01), aspherical ablation (P = 0.02), and larger transitional zone (TZ) (P = 0.03). Steeper corneal curvature (Kmax) (P = 0.01), thicker preoperative central corneal thickness (P < 0.01), smaller preoperative myopia (P < 0.01), longer duration of myopia (P = 0.02), with contact lens (P < 0.01), and larger optical zone (OZ) (P = 0.02) were protective factors. Among the three groups, the MM-LASIK had the highest risk of postoperative myopic regression (P < 0.01). Conclusions The MM-LASIK group experienced the highest myopic regression, followed by the FS-LASIK and LASEK groups. Older age, aspheric ablation used, thicker postoperative central corneal thickness, and enlarging TZ contribute to myopic regression; steeper preoperative corneal curvature (Kmax), longer duration of myopia, with contact lens, thicker preoperative central corneal thickness, lower manifest refraction SE, and enlarging OZ prevent postoperative myopic regression in myopia from − 6.0D to − 10.0D.

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Twelve-Year Follow-Up of Laser In Situ Keratomileusis for Moderate to High Myopia

BioMed Research International ◽

10.1155/2017/9391436 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

Tetsuya Ikeda ◽

Kimiya Shimizu ◽

Akihito Igarashi ◽

Sumie Kasahara ◽

Kazutaka Kamiya

Keyword(s):

High Myopia ◽

Central Corneal Thickness ◽

Pearson Correlation ◽

Corneal Thickness ◽

Laser In Situ Keratomileusis ◽

Manifest Refraction ◽

Observation Period

Purpose. To assess the long-term clinical outcomes of conventional laser in situ keratomileusis (LASIK) for moderate to high myopia.Methods. We retrospectively examined sixty-eight eyes of 37 consecutive patients who underwent conventional LASIK for the correction of myopia (−3.00 to −12.75 diopters (D)). At 3 months and 1, 4, 8, and 12 years postoperatively, we assessed the safety, efficacy, predictability, stability, mean keratometry, central corneal thickness, and adverse events.Results. The safety and efficacy indices were0.82±0.29and0.67±0.37, respectively, 12 years postoperatively. At 12 years, 53% and 75% of the eyes were within 0.5 and 1.0 D, respectively, of the targeted correction. Manifest refraction changes of −0.74±0.99 D occurred from 3 months to 12 years after LASIK (p<0.001). We found a significant correlation of refractive regression with the changes in keratometric readings from 3 months to 12 years postoperatively (Pearson correlation coefficient,r=-0.28,p=0.02), but not with the changes in central corneal thickness (r=-0.08,p=0.63). No vision-threatening complications occurred in any case.Conclusions. Conventional LASIK offered good safety outcomes during the 12-year observation period. However, the efficacy and the predictability gradually decreased with time owing to myopic regression in relation to corneal steepening.

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