We now have almost 30 years of expertise with the excimer laser. We started with PRK treatment on the corneal surface and initially saw regression – but that is now conquered. We had issues with early LASIK procedures, particularly with flap creation, but continued improvements to microkeratomes and in surgical technique resolved them. But even with a microkeratome, LASIK was a huge improvement over the original surface ablations, and with the introduction of the femtosecond laser for flap creation, microkeratome use became less popular, and femtosecond LASIK came to be the preferred procedure.
Wavefront-guided LASIK was introduced in 2001, which offered more predictable and improved excimer laser beam delivery. Given that the predicted and postoperative outcomes are so close, some or much of the statistical differences between them are statistical noise, so it’s clear that the procedure is becoming extremely precise. Iris registration for astigmatic improvement arrived next, improving not only astigmatic alignment, but also registration of higher order aberrations. Further, improvements in iris registration, cyclotorsion, laser calibration and stability, and very high resolution wavefront sensing have all taken place. Simply put, we are now approaching the limits of accuracy with excimer laser based corneal ablation.