Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis

Factors Predicting Loss of Best-Corrected Visual Acuity After Hyperopic Laser-Assisted In Situ Keratomileusis

PURPOSE

The aim of this study was to identify risk factors for the loss of corrected distance visual acuity (CDVA) after uncomplicated hyperopic laser-assisted in situ keratomileusis (LASIK).

METHODS

A retrospective study including hyperopic patients who underwent microkeratome-assisted LASIK between January 2000 and December 2019 at Care-Vision Laser Centers, Tel-Aviv, Israel. Loss of CDVA was defined as ≥ 2 lines (0.20 logarithm of the minimum angle of resolution [logMAR] increase). Excluded were patients who had loss of CDVA because of intraoperative or postoperative complications or developed cataract at their final visit.

RESULTS

Overall, 1998 eyes of 1998 patients were included in the study, of which 35 eyes (1.75%) had CDVA loss at final follow-up (mean 387 days). The vision-loss group had a significantly greater spherical treatment (3.4 vs. 2.8 D, P = 0.02), ablation depth (69.4 vs. 53.8 μm, P = 0.01), a higher proportion of treatments with a smaller optic zone (6.0 mm) (31.4% vs. 13.4%, P = 0.002), treatment with the EX200 (Alcon) excimer rather than the EX500 (Alcon) (74.3% vs. 39.0%, P < 0.001), and treatment with the Moria M2-90 microkeratome rather than the Moria Sub-Bowman's keratomileusis (SBK) microkeratome (65.7% vs. 29.6%, P < 0.001). In multivariate binary logistic regression, factors that remained significant predictors of CDVA loss were a greater spherical treatment (per 1 D treatment, odds ratio = 1.42, 95% CI, 1.11-1.81, P = 0.004) and the use of the Moria M2-90 microkeratome (odds ratio = 4.66, 95% CI, 2.30-9.45, P < 0.001).

CONCLUSIONS

In patients undergoing uncomplicated hyperopic LASIK, a greater spherical hyperopic treatment is associated with a higher risk for vision loss. Transition to a newer microkeratome model significantly reduced vision loss rate.

Three-Year Follow-Up of Laser In Situ Keratomileusis Treatments for Myopia: Multi-Center Cohort Study in Korean Population

This multi-center cohort study included 3401 myopic laser in situ keratomileusis (LASIK) procedures conducted in 1756 myopia patients between 2002 and 2005. Pre- and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and manifest refraction spherical equivalent (SE) were recorded. Factors predicting low postoperative efficacy (defined as a postoperative UCVA < 0.5) were identified using univariate and multivariate logistic regression analysis. Compared with 1 month postoperatively, logMAR UCVA at 3 months postoperatively was significantly decreased (p = 0.002) and that at 2 and 3 years was significantly increased (p < 0.001). LogMAR BCVA at 2 years postoperatively was significantly decreased compared with 1 month postoperatively (p = 0.008). Over the 3-year postoperative period, overall refractive predictability within ±1.00 D and ±0.50 D ranged from 69.0% to 86.2% and from 43.3% to 67.8%, respectively. This also decreased from 1 month to 6 months postoperatively (p < 0.005). Multivariate logistic regression analysis using generalized estimating equations, revealed that higher preoperative SE (odds ratio [OR], 2.58 and 7.23; p < 0.001) and lower preoperative BCVA (OR, 2.44; p = 0.003) were predictive of a low postoperative efficacy. In summary, myopic LASIK can be effective and safe with a high refractive predictability in a Korean population, but myopic regression occurs over time. Higher preoperative SE and lower preoperative BCVA are predictive of a low postoperative efficacy.