This article is more than 5 years old. Information may no longer be current.
Corneal power may increase up to 7 years after LASIK
Corneal stability was achieved 1 year after PRK, while instability remained 7 years after LASIK, according to a study.
In the prospective study, 45 patients with myopia of –6 D to –8 D were randomized to receive either PRK or LASIK. PRK was performed in 20 patients, and LASIK was performed in 25 patients. Follow-up continued up to 7 years postoperatively.
At 3 years postop, 16 PRK patients and 15 LASIK patients were available for examination. At 7 years postop, nine PRK patients and seven LASIK patients were available for examination.
In LASIK patients, corneal power increased from 44.39 ± 1.80 D at 1 month postop to 45.01 ± 1.87 D at 1 year postop (P < .01). Corneal power also increased from 1 to 3 years postop (P < .05) and from 3 to 7 years postop (P < .05).
In PRK patients, corneal power increased from 44.26 ± 1.82 D at 1 month postop to 45.39 ± 2.16 D at 1 year postop (P < .001). No significant changes were observed past the 1-year follow-up.
Spherical aberrations were significantly higher at all follow-up points after LASIK than prior to surgery (P < .01).
With PRK, spherical aberrations increased significantly at 1 month postop (P < .001). At all follow-up points between 3 months and 7 years, spherical aberration remained stable and significantly higher than before PRK (P < .01).
“Although newer lasers and treatment algorithms may show higher refractive predictability and less induction of higher-order aberrations, the results suggest that surgically induced higher-order aberrations do not readily diminish over time,” the study authors said.