What is the difference between rk and prk

Some pilots, rightly or wrongly, feel their chances of being hired by a major commercial airline are reduced if they wear glasses. Others may choose not to wear glasses for appearance or image reasons.

Athletes engaged in sports and water sports or in windy environments may not find contact lenses suitable for their sport. Advances in ophthalmologic surgery have given some visually deficient people the opportunity to enjoy near normal distant vision without corrective lenses.

Advertising by eye centers inundates all forms of the media now. The various techniques and claims may be very confusing to the lay person. The pilot or controller is also concerned with the implications for medical certification if he or she were to undergo one of these procedures.

What is the true story? Errors in refraction causing impaired visual acuity arise from abnormalities in the anatomy of the eye. These errors are in either the cornea of the eye or from the length of the globe of the eye.

Until recently, glasses and contact lenses to compensate for corneal abnormalities were the only option to correct these conditions. A type of contact lens program to temporarily alter the shape of the cornea, called Orthokeratology orthoK , is also used. This did not allow permanent freedom from corrective lenses as the molded cornea would gradually return to its original shape.

The FAA originally did not allow pilots to correct their vision using Ortho-K lenses, except for the condition known as keratoconus. Must have in possession glasses to correct for distant vision.

Research in the former Soviet Union evaluated the possibility of surgically altering the shape of the cornea to give improved vision without corrective lenses. The science and art of refractive surgery has rapidly evolved. Four basic surgical techniques are currently used to change the shape of the cornea.

The earliest technique developed is the Radial Keratotomy RK. A variation of this procedure is call the Astigmatic Keratotomy AK. Later, techniques using laser to remove portions of the cornea were developed. Newer techniques include the use of implantable intracorneal rings and artificial intraocular lenses.

A relatively newer technique for correcting farsightedness is Conductive Keratoplasty. Wave-front technology is also a new technique to correct refractive errors of not only the cornea, but also those generated from the lens to the retina.

None of the procedures mentioned corrects for the age related changes in vision, termed presbyopia, and may make the need for reading glasses arise sooner in previously nearsighted individuals. One technique, termed monovision refractive surgery, corrects one eye for distant vision and the other eye for near vision.

The FAA has approved monovision refractive surgery for pilots, after a six month adjustment period to the surgery. This procedure has not been approved for controllers. They do not correct other vision problems such as Age Related Macular Degeneration, glaucoma, cataracts, retinal detachments and blindness due to diabetes or trauma. Radial keratotomy RK attempts to change the shape of the cornea by making radial cuts in the periphery of cornea. The radial cuts have a similar appearance to spokes of a bicycle when looking directly at the cornea.

These cuts tend to flatten the cornea and correct myopia or nearsightedness. Generally, RK involves making four to sixteen radial incisions depending on the amount of flattening desired. By making curved corneal incisions, some degree of astigmatism irregular curvature of the cornea may also be corrected. This is known as Astigmatic Keratotomy. The cuts are usually made with a scalpel after mapping of the cornea determines the amount of flattening desired.

Generally, only one eye is done at a time to allow healing and pain relief, since the eye is usually patched after surgery. RK is rarely performed today in the U. Yes, fluctuation of the vision during the day as a result of RK is very common and will continue, even if another procedure is performed.

It is very important to inform your surgeon before any follow-on procedures if fluctuation exists. Occasionally, follow-on procedures may still be performed to reduce the amount of vision prescription at the present time, through its various fluctuations. If you experience fluctuation in your vision throughout the day, be sure to ask your surgeon how that will be managed and dealt with after your 2nd procedure. It is important to be aware that all surgery comes with some risk, and no result can ever be guaranteed.

No surgery should be presented in such a way that you are made to believe it will be perfect in every way. Developed in the s in Russia, RK was the very first refractive surgical procedure to gain ground in North America. In an RK procedure, a surgeon makes small but deep incisions in the cornea with the goal of flattening it. Since myopia often results from an excessive curvature of the cornea, this procedure will ideally help to reduce issues like nearsightedness and astigmatism.

Often, surgeons will perform RK on one eye and then wait up to six weeks before performing surgery on the second eye. This delay allows the surgeon to monitor the first eye and record the results of the surgery. The results of the surgery on the first eye will often influence how the surgeon performs the surgery on the second eye. In the meantime, the patient will be fitted for contact lenses for the uncorrected eye to ensure more equal and consistent vision between the eyes.

While many patients praised the effects of RK in the early days, long-term results of the surgery have not all been as positive. Many RK patients suffer from permanent vision damage and other long-term complications. The complications include:. You can go blind from Lasik. Total blindness -- meaning, no light perception -- from Lasik is extremely rare, but it has happened.

How many years does PRK last? The results of your PRK do not diminish over time. Once your eyes have stabilized, usually in three to six months, your vision correction is permanent. This doesn't mean, however, that your vision won't change. Is radial keratotomy still performed? People who have had RK may have later complications such as fluctuations of vision.

Is Lasik worth it over 40? At around age 40 your eyes start to change and you may develop presbyopia — farsightedness due to age — which could affect your candidacy for LASIK. Can you do PRK twice?

Just like your prescription for eyeglasses has changed slowly over time, so too, will your vision after laser eye surgery. Is vision bad?