Photorefractive keratectomy (PRK) is the original laser vision correction surgery that was first performed in the US in the 1980’s and on June 12, 1990 at the Gimbel Eye Centre in Calgary Alberta Canada. In the 25 years that followed PRK first gained in popularity over radial keratotomy (RK) in which incisions were made in the cornea to flatten the surface of the eye for treatment of nearsightedness. PRK has the advantage of precision laser modification of the corneal curvature using the excimer laser. The excimer laser was originally intended for industry and manufacturing but when a curious researchedr took some leftover Thanksgiving turkey back to to lab laser vision correction was born.
PRK quickly replaced RK as a more stable and precise way to eliminate the need for glasses or contact lenses. As the search for improvements continued into the 1990’s the older technology of cutting a corneal flap was combined with the excimer laser reshaping in a treatment that was first called “FLAP & ZAP” and later laser in situ keratomileusis (LASIK). LASIK quickly overtook PRK as the most popular laser vision correction method into the early years of this century due to the faster healing the flap allows. Throughout this time PRK remained a trusted method and was considered safer than LASIK for thinner corneas and for athletes and people with occupations that might risk eye injury due to the risk of a LASIK flap shirt.
As the early 2000’s progressed a new and difficult to treat complication became recognized – corneal ectasia. Ectasia after LASIK is uncommon but can result in an unstable corneal surface that is analgous to a weak spot in a tire, which makes the surface of the eye bulge out and become irregular over time. There has been a lot of debate about ectasia after LASIK, but many eye surgeons believe that PRK may be a lower risk for this specific problem due to the fact that the cornea is not disrupted as deeply as compared to LASIK. The LASIK flap does not leave the eye but once it is cut it may no longer contribute as strongly to the corneal structure. This weakening in addition to a number of other risk factors appears to play a role in post LASIK ectasia. All the while PRK has continued to be offered as an option for laser vision correction in particular for people who might not qualify for LASIK.
In the past few years many surgeons around the world have moved “back to the surface” and choose not to cut corneal flaps in order to affect the smallest amount of corneal tissue needed to improve uncorrected vision. Advances over the last quarter of a century since PRK was first done include significant advances in excimer laser technology including iris recognition, cyclotorsion adjustments, and the ability to do individually customized treatments using wavefront technology. In addition, improved bandage contact lenses and medications have been developed to reduce post-operative discomfort and risk for haze following PRK.
PRK turns 25 this year in Canada and is still going strong!
If you have questions about laser vision correction or wish to book a complimentary evaluation with Dr. Anderson Penno, contact Western Laser Eye Associates.