Possible Complications
Some complications that can be temporary or permanent include:
- Dry eyes
- Recurrent erosions during sleep
- Long healing period
- Pain
- Glare, halos, or starburst Aberrations
- Increased ocular straylight
- Under- or over-correction
- Recurrence of myopia
- Corneal haze
- Scarring
- Reduced best corrected visual acuity
- Reduced acuity in low light
- Increased sensitivity
As with other forms of refractive surgery, Lasik, Epi-Lasik, Lasek, Trans-PRK and so forth, 'dry eyes' is the most common complication of PRK surgery and can be permanent. Recurrent erosions occur while sleeping when the dry corneal epithelium becomes adherent to the upper eyelid, causing pain during REM sleep.
PRK may be rarely performed on one eye at a time to assess the results of the procedure and ensure adequate vision during the healing process. Activities requiring good binocular vision may have to be suspended between surgeries and during the sometimes extended healing periods.
A few post-PRK patients have complained of glare, halos, and starburst aberrations, which may be the result of postoperative corneal haze that may develop during the healing process. Using modern lasers as of the year 2005, this is quite rare after 6 months but reportedly, symptoms have occasionally lingered longer than a year in some cases. A dilute concentration of the chemotherapeutic agent, Mitomycin-C, may be applied briefly at the end of the procedure to reduce the incidence of haze formation.
Predictability of the resulting refractive correction after healing is not totally exact, particularly for those with more severe myopia. This can lead to under/over-correction of the refractive error. In the case of the over-correction, premature presbyopia is a possibility. Experienced surgeons employ a custom-profile algorithm to further enhance predictability in their results.
In 1 to 3% of cases, loss of best corrected visual acuity (BCVA) can result, due to decentered ablative zones or other surgical complications. PRK results in improved BCVA about twice as often as it causes loss. Decentration is becoming less and less of a problem with more modern lasers using sophisticated eye centering and tracking methods.
Read more about this topic: Photorefractive Keratectomy