Risk factors for retreatment and a comparative analysis of wavefront-guided versus conventional treatment for residual myopic and hyperopic correction in LASIK
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A retrospective chart review performed from December 2007 to September 2012 identified 3,223 patients that underwent LASIK treatment with the STAR S4 IRTM Excimer Laser. In this group, 109 patients (3.4%) required a retreatment. All charts were reviewed for pre-operative age, gender, initial manifest refraction spherical equivalent (MRSE), total astigmatism, and method of primary LASIK treatment (conventional versus wavefront-guided) to identify risk factors that may lead to retreatment. A second chart review from December 2007 to January 2013 identified 120 patients who had a retreatment. A comparative analysis on the final post-operative visual acuity and MRSE was performed on this group to evaluate the efficacy of conventional versus wavefront-guided retreatment. Increased incidence rates of retreatment post- LASIK were associated with pre-operative age greater than 40 years (p < 0.001), initial MRSE greater than -5.0 diopters (D) (p < 0.004), hyperopia (p <0.031), and astigmatism greater than -1 D (p < 0.001). There was a 12.3% incidence rate of epithelial ingrowth post-retreatment, and a 1.7% development of clinically significant epithelial ingrowth, which necessitated flap lift and scrapping. There was no statistically significant difference in visual acuity and MRSE post- retreatment with either conventional or wavefront-guided retreatment for residual hyperopic or myopic refractions. All secondary retreatments were in the wavefront-guided retreatment groups (myopic p = 0.16 and hyperopic p = 0.01). Ablation depth was significantly different between myopic conventional and wavefront-guided (p = 0.01) and hyperopic conventional and wavefront-guided (p = 0.04). While no statistically significant difference was found between final outcome vision between conventional and wavefront-guided treatments, conventional treatment ablating less corneal stroma and resulting in fewer complications and additional retreatments provides a strong argument for retreatment with conventional over wavefront-guided.
Thesis (M.A.)--Boston University