Visual acuity and corneal topography stability after 5 years of laser-assisted in-situ keratomileusis

ABSTRACT

Corneal topographic analysis has been established as an invaluable tool for the refractive surgeon. The use of corneal topography in assessment of corneal surface has tremendously advanced the development and evaluation of refractive surgeries. The analysis of corneal topography permits the recognition of normal and abnormal patterns of ablation, documentation of decentrations following Laser-Assisted In-Situ Keratomileusis [LASIK] surgery and also allows the refractive surgeon to quantify irregularities of corneal surface. Despite numerous follow-up studies on incidence of refractive regression and other complications after LASIK ablation, little attention has been paid to the long-term effect of LASIK surgery on corneal surface remolding and the consequential effects on the stability of vision. To evaluate the postoperative corneal changes on patients at the risk, after 5 years of undergoing LASIK surgery. Also, we tried to assess the stability of vision within this period to determine if there was a significant topographic pattern changes. Methods: Subdividing our subjects [40 eyes] to three groups of risk factors depending on their corneal topographic patterns. Mean age of subjects were 32.3 +/- 5.5 years [range 23 to 41 years] with a spherical equivalent manifest refraction [SEMR] ranging from -1.75 D to -13.75 D and a manifest refractive cylinder of less than 4.00D. Intended ablation depth ranged from 26.5 to 107.7 microns and the retrospective pachymetry value of 501 and 607m. There was a 100% improvement [p = 0.0001] in visual acuity in the groups with steep cornea and asymmetric bow tie, and a 60% improvement [p = 0.0001] in the inferior steepening cornea group. Also, there was a change in topographic pattern of each group with normal patterns being only associated with Steep Cornea and Asymmetric Bow tie groups while corneal ecstasies were observed in 3 eyes belonging to the inferior steepening group. Decreased thickness of residual Stroma, depth and width of ablation, older ages, increased myopic correction and abnormal corneal topography are some predisposing factors to unstable vision after LASIK correction. A significant change in VA and corneal topography were returned on assessment