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GD Kymionis, S Panagopoulou, C Siganos, M Theodorakis, I Pallikaris; Induced Optical Consequencies by Flap's Creations During LASIK . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2078.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To determine the effects of lamellar corneal flap’s creation during LASIK on ocular aberrations (3rd and 4th order), refraction and visual acuity. Methods:We investigated the optical consequences of lamellar corneal flap creation by monitoring changes in refraction, visual acuity and aberration in 16 myopic eyes (mean preoperative refraction 5.04D, ranged from –1.25 to –10.00 D) before (one week) and after two months of the lamellar flap’s creation, during a two steps LASIK procedure. The flapmaker microkeratome was used to create a lamellar corneal flap, while after two months, the flap was lifted and stromal ablation was performed. A Shack-Hartmann aberrometer was used to measure aberrations. Root-mean-square (RMS) wavefront error was used as an image quality metric before and after the flap’s creation. Results:There was no significant change in refraction between preoperative examination and post-flap follow-up (spherical equivalent pre-flap: –5.04+ 2.12 to post-flap: -4.94+2.07, p=0.27). In addition there was no change in visual acuity. (preflap: UVA:0.05, BCVA:0.96 vs. postflap: UVA:0.05, BCVA: 0.94, p=0.41). There was a statistically significant increase in total high order wavefront aberrations after flap’s creation (RMS pre-flap:0.441+0.23, post-flap:0.564+0.36, p=0.03). The spherical aberration component increased from 0.274 before, to 0.343 after flap’s creation (p=0.001). In parallel, there was a statistically significant increase in third order coma along the flap’s hinge axis (x-axis) (pre-flap:0. 299 to post-flap:0. 505, p=0.001) while similar observation was not found for third order coma along y axis (pre-flap:0. 698 to post-flap:0. 718, p=0.09). Conclusion:Our results highlight the fact that the lamellar cut made by the microkeratome can modify the existing nature ocular aberrations (especially spherical and coma-like aberrations along the flap’s hinge axis), while visual acuity and refraction remain stable.
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