Causes of the Lower Uncorrected Visual Acuity than 20/40 after LASIK

ABSTRACT

PURPOSE: To evaluate the causes of low uncorrected visual acuity below 20/40 after LASIK (laser in situ keratomileusis). METHODS: 289 eyes (more -6.0 D myopia) that had LASIK between July 1997 and December 1999 by one surgeon were observed for at least 6 months. We evaluated their uncorrected visual acuity and ocular state. RESULTS: 51 eyes (17.64%) of 289 eyes have lower uncorrected visual acuity than 20/40 after LASIK. The causes were myopic regression (22/51), decentering (10/51), undercorrection of myopia (5/51), corneal ectasia (5/51), undercorrection of astigmatism (4/51), central island (2/51), free flap (1/51), postoperative flap displacement (1/51) and incomplete keratome pass (1/51). CONCLUSION: Although LASIK is a safe and effective procedure, many patients had lower uncorrected visual acuity less than 20/40 after LASIK. We must be able to manage correctable factors among the causes above.