Radial Keratotomy was a refractive procedure developed in the Soviet Union and involved making radial incisions in the cornea. This flattened the tissue reducing the amount of nearsightedness. Most of these patient's corneas changed over time resulting in either regression to nearsightedness again or the more common ending, farsightedness with astigmatism. These latter patients usually have "softer" corneas and frequently have irregular refractions and are not always correctable to 20/20.

The big question that then asked is, " what procedure can I have to correct my vision now"? These has been considerable discussion as to weather PRK or LASIK is better for these patients. As usual, there are always as many answers and opinions. Many refractive surgeons prefer doing LASIK after RK for 2 reasons. The first is that there is a reduced incidence of post operative corneal haze as opposed to PRK. The second is that it still leaves PRK as a third procedure should one be required to finalize the refractice corneal power.

Studies performed by the FDA during the 1990s demonstrated that in addition to the increased likelihood of the post operative haze with PRK there was also a tendency to heal unpredictably. With the introduction of Mitomycin to be used after PRK, there was a substantially lower incidence of corneal haze. This was a huge step forward in improving the results and an increase in PRK procedures. One consideration though is the long term side effects of Mitomycin use. These are still unknown and only time will give us the answer. Furthermore, there is an increased incidence of corneal haze with each PRK performed. Thus a surgeon must factor this into his/her equation when deciding what procedure to perform. If an enhancement must be done years after the initial one, PRK may not be available if corneal haze may be the result. In addition, the increased risk of hyperopic shift after RK always lurks in the shadows. As a result, a number of refractive surgeons prefer doing LASIK as the first procedure after RK leaving PRK as a back up should it be needed.

While there is no data linking increased cataract development in post refractive surgery patients, many will get them as they age. These surgically altered corneas will make implant calculations much more difficult. In addition, will there be secondary problems with the inner most layer of the cornea, the endothelial cell layer, affecting the cataract procedure.

Another consideration when choosing LASIK over PRK after RK is the risk of intrastromal bubbles escaping through the RK incisions and getting trapped between the epithelium and the focusing lens. This in turn blocks the laser and the flap can not be made. The procedure would have to be stopped and reperformed in 6 months using a microtome instead of intralase.

In summary, choosing either PRK or LASIK after RK depends on a host of factors and making the wrong choice can have very detrimental affects. As always only an experienced refractive surgeon should be called upon when enhancing an RK altered eye.