Better pain management may help PRK make a comeback
PRK: Like LASIK, but with more "ouch"
The PRK procedure is very similar to LASIK, and uses the same type of laser to reshape the cornea. But in PRK, the refractive surgeon does not create a corneal flap. Instead, the outer later of the cornea (the epithelium) is removed prior to using the excimer laser to reshape the underlying corneal tissue. After the laser treatment, a bandage contact lens is placed on the eye until the protective epithelium can grow back, which usually takes a week or so.
Until the epithelium is healed and intact, the eye after PRK surgery is uncomfortable and sensitive to light. Vision is also usually blurred for a week or so, to the extent that the patient may not be able to drive for several days after surgery. For these reasons, PRK never gained popularity.
LASIK to the rescue
Soon after PRK arrived on the scene in the mid 1990s, LASIK was introduced. In LASIK, the refractive surgeon creates a flap of corneal tissue before reshaping the underlying cornea with the excimer laser. When the flap is replaced, it acts as a living, pain-controlling bandage. With LASIK, there is very little discomfort after surgery, and vision is usually quite clear within hours.
But LASIK has its own drawbacks. Up to 37% of patients can have symptoms of dry eye 6 months after LASIK surgery, and LASIK may compromise the structure of the cornea if the laser treatment penetrates too deep into the cornea, especially if the corneal flap is large. This could lead to a serious complication called corneal ectasia.
A move back to PRK?
Since there is no corneal flap created in PRK, the laser treatment can occur with less damage to corneal nerve endings (which contributes to dry eye after LASIK) and less damage to the stronger fibers within the cornea that help it maintain its proper shape (perhaps reducing the risk of ectasia).
Because of these factors, PRK may be a safer procedure than LASIK for some refractive surgery patients, especially those with thin corneas or symptoms of dry eye prior to surgery. Also, many refractive surgeons prefer PRK to LASIK because it eliminates the risk of a flap complication.
The major drawbacks to PRK have always been post-operative pain and temporarily blurred vision. But there now appears to be an answer to these problems.
A new topical (eye drop) anti-inflammatory medication called Xibrom (Ista Pharmaceuticals) appears to be significantly more effective at controlling post-operative pain and blurred vision after PRK surgery.
According to refractive surgeon Ming Wang, M.D. (Wang Vision Institute, Nashville TN), Xibrom has made his PRK patients noticeably more comfortable after PRK surgery, and has improved their visual acuity the day after surgery as well. Dr. Wang reports that soaking the bandage contact lens he applies after PRK with Xibrom has "dramatically decreased patients' discomfort during the first 24 hours (after PRK surgery)," enabling many of his patients to not need any oral pain medications after the procedure.
Using a new and effective non-steroidal anti-inflammatory eye drop like Xibrom, "enables us to do what we feel is in our patients best interests without disrupting their daily lives and decreasing the 'wow factor' of elective surgical vision correction," adds Dr. Wang.
Consult with your eye doctor
If you are considering refractive surgery, don't forget to ask your eye doctor about PRK. While there is still more discomfort after PRK than LASIK, PRK eliminates the risk of flap complications and may decrease your risk of dry eyes or ectasia after laser vision correction. And with more effective pain control medications, the reasons to consider PRK over LASIK may be more compelling than ever.
Most LASIK surgeons will perform PRK surgery as an alternative to LASIK upon request or if they feel there is compelling reason to do so.
SOURCE: Improvements in pain management aid surface ablation outcomes. Ocular Surgery News; Vol 25, No 25. October 15, 2007. pp 52-54.
