Thin-flap LASIK provides faster results than PRK, study says

Though LASIK is the most popular laser vision correction surgery in the United States, photorefractive keratectomy (PRK) eliminates the risk of intra-operative and post-operative flap-related complications.

Recently, a variation of LASIK called sub-Bowman keratomileusis (SBK) or "thin-flap LASIK" has been gaining popularity among LASIK surgeons. A thinner corneal flap is created in SBK, which may reduce certain LASIK risks — particularly dry eyes and corneal ectasia.

To compare the outcomes produced by thin-flap LASIK with those produced by PRK, researchers Stephen G. Slade, MD, Daniel S. Durrie, MD, and Perry S. Binder, MD recently conducted a study of fifty patients, performing thin-flap LASIK on one eye and PRK on the other eye of each patient.


Thin-flap LASIK vs PRK: Study design and methods

Of the 100 eyes in the study, the mean pre-operative refractive error was -3.66 diopters (D) of nearsightedness and -0.66 D of astigmatism.

Eyes in the thin-flap LASIK group had a corneal flap created with a 60-Hz IntraLase femtosecond laser (Abbott Medical Optics, Santa Ana, CA). The intended flap thickness was 100 microns, which is about 20 to 40 percent thinner than conventional LASIK flaps.

All eyes in both groups underwent a customized laser ablation with a LADARVision 4000 CustomCornea excimer laser (Alcon Laboratories, Fort Worth, TX)

Follow-up exams were performed one, three and six months after surgery. Measurements performed at each visit included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity, corneal topography and wavefront aberrometry.


Thin-flap LASIK vs PRK: Study results

Data gathered during the follow-up visits yielded the following results:
One month after surgery, 88 percent of thin-flap LASIK eyes achieved UCVA of 20/20 or better, compared with 48 percent of PRK eyes.


Six months after surgery, there was no significant difference in UCVA of eyes in the two groups: 92 percent of thin-flap LASIK eyes and 94 percent of PRK eyes had UCVA of 20/20 or better.


At one and three months, the thin-flap LASIK eyes had less significant higher-order aberrations (including spherical aberration) than the PRK eyes.


Six months after surgery, there was no significant difference in higher-order aberrations between the two groups.

Thin-flap LASIK vs PRK: Study results

The researchers concluded that quality of vision recovered faster in eyes undergoing thin-flap LASIK compared with eyes undergoing PRK, but at six months there were no significant visual differences between the two groups.

The results of the study show that both thin-flap LASIK and PRK produce excellent visual outcomes.

One implication of this study if you are considering laser vision correction and want no possible risk of LASIK flap complications, PRK provides comparable visual acuity to thin-flap LASIK, but you probably will have to wait a few weeks longer after surgery for optimum visual acuity.