Refractive 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 complaints of 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 low myopia (generally less than –6.00 D) revealed that 56%–86% of eyes treated with either PRK or LASIK achieved uncorrected distance visual acuity (UDVA; also called uncorrected visual acuity, UCVA) of at least 20/20, 88%–100% achieved UDVA of at least 20/40, and 82%–100% were within 1.00 D of emmetropia. Up to 2.1% of eyes lost ≥2 lines of corrected distance visual acuity (CDVA; also called best-corrected visual acuity, BCVA). Reports since 2000 have demonstrated significantly improved outcomes and safety profiles, with <0.6% of eyes losing 2 or more lines of CDVA.

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.

Fares U, Otri AM, Al-Aqaba MA, Faraj L, Dua HS. Wavefront-optimized excimer laser in situ keratomileusis for myopia and myopic astigmatism: refractive outcomes and corneal densitometry. J Cataract Refract Surg. 2012;38(12):2131–2138. Epub 2012 Oct 18.

Fernández AP, Jaramillo J, Jaramillo M. Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of –6 D or less using the Nidek EC-5000 laser. J Refract Surg. 2000;16(6):711–715.

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. Epub 2013 Feb 21.

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.

Tan J, Simon D, Mrochen M, Por YM. Clinical results of topography-based customized ablations for myopia and myopic astigmatism. J Refract Surg. 2012;28(Suppl 11): S829–S836.

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.

Outcomes for Hyperopia

In myopic ablations, the central cornea is flattened, whereas in hyperopic ablations, more tissue is removed from the midperiphery than from the central cornea, resulting in an effective steepening (Fig 5-1B). To ensure that the size of the central hyperopic treatment zone is adequate, a large ablation area is required for hyperopic treatments. Most studies have employed hyperopic treatment zones with transition zones out to 9.0–9.5 mm. FDA clinical trials of PRK and LASIK for hyperopia up to +6.00 D reported that 46%–59% of eyes had postoperative UDVA of 20/20 or better, 92%–96% had UDVA of 20/40 or better, and 84%–91% were within 1.00 D of emmetropia; loss of >2 lines of CDVA occurred in 1%–3.5%. The VISX FDA clinical trial of hyperopic astigmatic PRK up to +6.00 D sphere and +4.00 D cylinder reported an approximate postoperative UDVA of 20/20 or better in 50%