2020–2021 BCSC Basic and Clinical Science Course™
13 Refractive Surgery
Chapter 5: Photoablation: Techniques and Outcomes
As the early broad-beam excimer laser systems improved and surgeons gained experience, the results achieved with surface ablation and LASIK improved markedly. The ablation zone diameter was enlarged because it was found that small ablation zones, originally selected to limit depth of tissue removal, produced more haze and regression in surface ablation treatments and concerns about subjective glare and halos for both surface ablation and LASIK. The larger treatment diameters currently used, including for optical zones and gradual aspheric peripheral blend zones, improve optical quality and refractive stability in both myopic and hyperopic treatments. Central island elevations have become less common with improvements in beam quality, vacuums to remove the ablation plume, and the development of scanning and variable-spot-size excimer lasers.
Solomon KD, Fernández de Castro LE, Sandoval HP, et al; Joint LASIK Study Task Force. LASIK world literature review: quality of life and patient satisfaction. Ophthalmology. 2009;116(4): 691–701.
Outcomes for Myopia
Initial FDA clinical trials of conventional excimer laser treatments limited to myopia of 6.00 D or less revealed that 56%–86% of eyes treated with either PRK or LASIK achieved uncorrected visual acuity (UCVA; also called uncorrected distance visual acuity, UDVA) of at least 20/20, 88%–100% achieved UCVA of at least 20/40, and 82%–100% were within 1.00 D of emmetropia. Up to 2.1% of eyes lost 2 or more lines of BCVA. Reports since 2000 have demonstrated significantly improved outcomes and safety profiles, with fewer than 0.6% of eyes losing 2 or more lines of BCVA.
el Danasoury MA, el Maghraby A, Klyce SD, Mehrez K. Comparison of photorefractive keratectomy with excimer laser in situ keratomileusis in correcting low myopia (from –2.00 to –5.50 diopters): a randomized study. Ophthalmology. 1999;106(2):411–420.
Kanellopoulos AJ, Asimellis G. Long-term bladeless LASIK outcomes with the FS200 femtosecond and EX500 excimer laser workstation: the refractive suite. Clin Ophthalmol. 2013;7:261–269.
Kulkarni SV, AlMahmoud T, Priest D, Taylor SE, Mintsioulis G, Jackson WB. Long-term visual and refractive outcomes following surface ablation techniques in a large population for myopia correction. Invest Ophthalmol Vis Sci. 2013;54(1):609–619.
Luger MH, Ewering T, Arba-Mosquera S. Influence of patient age on high myopic correction in corneal laser refractive surgery. J Cataract Refract Surg. 2013;39(2):204–210.
Sugar A, Rapuano CJ, Culbertson WW, et al. Laser in situ keratomileusis for myopia and astigmatism: safety and efficacy: a report by the American Academy of Ophthalmology. Ophthalmology. 2002;109(1):175–187.
Tole DM, McCarty DJ, Couper T, Taylor HR. Comparison of laser in situ keratomileusis and photorefractive keratectomy for the correction of myopia of –6.00 diopters or less. Melbourne Excimer Laser Group. J Refract Surg. 2001;17(1):46–54.
Watson SL, Bunce C, Alan BD. Improved safety in contemporary LASIK. Ophthalmology. 2005;112(8):1375–1380.
Excerpted from BCSC 2020-2021 series: Section 13 - Refractive Surgery. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.