Astigmatism : PRK & LASEK procedure
PRK (an acronym for photo-refractive keratectomy) is a form of laser surgery to correct astigmatism. It can also be used for mild degrees of hyperopia (farsightedness) and myopia (short-sight).
You will also see this treatment being referred to as LASEK and involves a minor difference in the handling of the surface skin layer. However, both procedures are identical in visual outcomes and pain. Healing time can take longer with LASEK, and so in practice PRK is the most common of these two ‘surface ablation’ techniques. In effect you could use the terms PRK and LASEK interchangeably.
PRK was the first type of laser eye surgery for vision correction and was first performed in 1988. It is the fore-runner to the most commonly performed procedure: LASIK.
PRK recovery takes a longer than recovery from LASIK eye surgery, between 3 and 5 days for most patients. The first 2-3 days are often painful and vision is not very clear.
PRK is still commonly performed and is used mainly when LASIK is not possible, for example a thin cornea or when the patient expresses a preference. Like LASIK excimer surgery, PRK works by reshaping the cornea allowing light entering the eye to be correctly focused on the retina for clear sight.
LASIK preferred over PRK
With the WaveLight system, we do not tell the laser which procedure is being performed – the excimer laser ablation is exactly the same for PRK and for LASIK.
LASIK is much preferred, however, for correcting astigmatism because with higher prescriptions the chance of a second enhancing re-treatment goes up. It is much easier to re-treat when a LASIK flap is already present and the whole second procedure can be completed in 3 minutes. With PRK re-treatment, you get the same pain and delayed healing with another week off work. PRK re-treatments are also less precise than those with LASIK.For both PRK and LASIK, the excimer laser sculpts the stromal layer of the cornea to correct your astigmatism and other associated correction. The main difference between PRK and LASIK is that with LASIK a thin, hinged flap is created on the cornea to access the inner layers; in PRK no flap is created - just the surface skin layer is removed and the excimer laser energy is applied to the top layer of corneal collagen (the stroma).