An Interview with Dr. Sher on PRK

Here are the most common questions patients ask me about PRK:

WHAT IS PRK?

PRK (photorefractive keratectomy) is a type of laser vision correction. It is a surgical procedure that utilizes the excimer laser to precisely alter the shape of the cornea by removing a small amount of corneal tissue from the outer layer to eliminate or greatly reduce nearsightedness, farsightedness and astigmatism. PRK surgery is extremely effective and can greatly improve vision without the need to cut a corneal flap, which is a necessary part of any LASIK procedure. 

HOW LONG HAVE YOU BEEN DOING PRK?

One of the very first excimer lasers in the country was obtained by the Phillips Eye Institute (PEI) in 1989 to evaluate the device for the treatment of corneal scarring and the feasibility of reducing nearsightedness. From 1989 through 1996, I participated in multiple clinical trials as part of a research team of ophthalmologists at the PEI. We published a series of articles on the results that were the earliest peer reviewed publications on this new and rapidly expanding field.  In 1996, PRK was approved for the treatment of nearsightedness (myopia) using one of the earliest commercial versions of the laser.

HOW HAS PRK CHANGED SINCE ITS INCEPTION?

The laser equipment and techniques to perform PRK have been continuously improving since 1996 When we first started doing PRK we could only treat mild nearsightedness; a few years later, we were able to treat higher degrees of nearsightedness. Eventually we were able to treat astigmatism and today we can also treat farsightedness. Excimer lasers are very sophisticated now; they can track and follow eye movement. The beam quality has improved greatly and the computers themselves are much more advanced. They are easier on the eye, produce less heat and reaction, and are incredibly reliable.

HOW DO YOU DETERMINE WHO IS A CANDIDATE FOR PRK AND WHAT IS INVOLVED IN THE CONSULTATION?

Patients who are considering PRK are given a thorough, dilated eye exam that includes additional tests specific for PRK such as mapping the cornea and wave front analysis.  My staff and I have a long discussion with the patient to determine whether he or she is a  good candidate. The lasers we use now are so advanced that they can treat patients with high levels of nearsightedness, farsightedness, and/or astigmatism.

Patients who choose not to go forward with  PRK end up receiving a very thorough medical eye exam -and will receive  a prescription for glasses.

WHAT ARE REASONS THAT SOME PATIENTS ARE NOT CANDIDATES?

Some patients have a refractive error that is too small to correct. Some individuals only want correction for near vision to avoid reading glasses.  PRK does not reverse the age-related need for reading correction. Patients with certain pre-existing medical conditions such as cataracts, uncontrolled glaucoma or uncontrolled diabetic retinopathy are not candidates for PRK. Also, the only people we consider for PRK are those who are able to understand the procedure and comply with our follow-up requirements, including post-procedure checkups.

WHY DO YOU PREFER PRK VS LASIK?

There are a number of reasons that I will list here but here is a short summary:

PRK and LASIK both use the same excimer laser and have the same excellent results. LASIK involves making a corneal flap on the eye, which permanently weakens the cornea and can cause dry eye. The PRK procedure doesn’t involve making a flap and doesn’t weaken the cornea.

A. PRK has fewer operative and post-operative complications:

The LASIK procedure is very safe but there are some potential complications inherent in creating the LASIK flap. LASIK flaps are made with a mechanical device called a microkeratome or more recently, a femtosecond laser that produces flaps of very exact depth and shapes.   In rare cases, with either method of flap creation, there is an imperfect flap. Other times; the flap can have microscopic wrinkles. In a small number of cases, there can be inflammation that occurs under the flap that needs to be treated. In a small number of eyes, cells from the surface can grow under the flap and need to be removed. Almost all of these and other complications can be treated successfully, however, it may involve extra medicines, doctor visits and on occasion, additional surgery. Almost all of these complications with LASIK involve problems with the flap.

The only serious potential complication of PRK is infection of the cornea. It is seen in only about 1 in 700 eyes. As we follow PRK patients very closely, a PRK infection (initially always superficial) is usually treated quickly and aggressively and in most cases does not result in a severe visual problem although that is possible. LASIK infections are also rare, but more serious because they are usually deep (under the flap) and topical antibiotic eye drops do not work well in these cases. The PRK procedure does not have any of these flap-related problems, since there is no flap.

B. PRK has equal or slightly better vision results than LASIK:

The visual results from both procedures are excellent.

C. PRK does not create dry eyes:

In LASIK, a flap is cut across most of the width of the cornea, which severs some of the nerves in the cornea. This means that your brain is not receiving the same number of signals from the corneal nerves to stimulate tear production. This can cause a lack of tears and a dry eye. This side effect can last for months. The dry eye produced with LASIK usually improves within 6 months, but can persist longer for some people. Older patients and patients with pre-existing dry eye are at more risk for more or worse symptoms. The PRK procedure does not alter long term tear production after surface healing is complete.

PRK does not weaken the cornea:

The LASIK procedure, by cutting collagen fibers in the cornea, can permanently weaken the cornea. In some patients, a pre-existing condition in which the eye has abnormal collagen fibers can be made much worse and cause the cornea to lose its intended shape. PRK almost never causes this weakening, called ectasia.

F. PRK is not susceptible to eye injury:

As explained above, The LASIK flap and cornea never heal back to their original strength. This flap, although sealed, can be dislodged or damaged by certain types of eye injuries. This is the reason that the US military prefers surface ablation (PRK) to LASIK for most situations and military specialties.

G. PRK has a long track record:

I have been performing PRK since 1989 and now have a small number of patients from the original trials in  1991-92 that I follow. These patients are now out over 25 years from surgery and are doing well, with good vision, no regression once healed and no apparent short or long-term ill effects on the eye.

H. PRK is better than LASIK in patients over 40

Certain complications of LASIK are more common in patients over age 40. The surface cells are not as tightly bound in people of that age and can slough off unexpectedly during a LASIK procedure, which can cause complications. With PRK, the surface cells are deliberately removed and grow back under controlled conditions and there is no flap for them to grow under. Dry eye is more common in older patients and, as explained above, can be aggravated by LASIK.

WHAT TYPES OF CORRECTION CAN BE ACHIEVED WITH PRK?

PRK treats all refractive errors including large amounts of nearsightedness, farsightedness and astigmatism. Patients in their mi- 40s or older will still need reading glasses. Monovision or the deliberate under-correction of one eye to allow for better near vision can be done.

IS ONE EYE DONE AT A TIME OR IS IT POSSIBLE TO DO TWO?

ONE EYE: There is less discomfort when patients do one eye at a time and the ophthalmologists at Eye Care Associates prefer to do it this way. The doctors often learn about the healing response from the first eye, and in some cases they may vary what they do with the second eye. When only one eye is done at a time, most patients can go to work the next day.

TWO EYES: For  patients travelling long distances or for deploying military personnel, both eyes can be done at once. However, when patients have both eyes done, they will not be able to resume work as quickly until the eyes heal enough to enable adequate vision.  This amount of time varies depending on the patient and degree of refractive error treated.

HOW MUCH PAIN IS INVOLVED IN PRK?

The PRK surgery itself is painless. A postop regimen most ophthalmologists use is very successful in controlling postoperative discomfort or pain. Most patients equate the post-operative experience with a “foreign body sensation”, like the feeling of having an eyelash in their eye or a “bad contact lens day”. There is rarely significant pain with PRK and it rarely lasts more than a day or two. When it is encountered, the discomfort is frequently the result of a dislodged or poorly-fitting bandage contact lens, and that can be easily replaced.

WHAT ARE THE LONG TERM RESULTS?

We have had excellent results and 25 years of follow-up from the first patients treated at Phillips Eye Institute. The results show that the corrections remain stable, they don’t need touch ups and the correction does not regress. There is no long-term damage to the eye and it doesn’t cause diseases such as cataracts, glaucoma or macular degeneration. PRK is very safe and effective.

WHAT HAPPENS AFTER THE SURGERY?

Most patients see an improvement in vision immediately. The higher the correction the more striking the improvement is, even before the patient gets up from the laser bed.

During the first week when the surface cells are healing and there is swelling of the cornea, the vision will fluctuate and appear to not be improving.  A temporary bandage contact lens is used to improve healing on the surface of the cornea. Once this contact lens has been removed, the vision rapidly improves. Most patients have driving vision a week or two after the surgery.

WHO PERFORMS THE PREOPERATIVE EVALUATION AND POSTOPERATIVE CARE?

At Eye Care Associates, my fellow surgeons and I believe that the surgeon should perform the preoperative and postoperative care.  We have very highly skilled technicians that assist us as we have a team approach.

HOW SAFE IS THE PROCEDURE?

PRK is an extremely safe procedure.  There exists, as with any surgery, the risk of complications. They are relatively rare and generally can be handled. In fact, PRK surgery is safer than long term contact lens wear. The discussion of the safety, risks and benefits is a very important one and we talk to each patient about all these issues in detail during their consultation.

WHAT IS THE PREPARATION LIKE BEFORE THE CONSULTATION AND SURGERY?

Before coming in for a PRK consultation, patients are asked to stop wearing their contacts for two weeks. Patients must also stop wearing their contacts for three days prior to the surgical procedure.  Before surgery, patients also need to discontinue wearing eye makeup for a few days and clean their eyelids daily for a short period.

WHERE DO YOU PERFORM THE SURGERY?

The surgery is performed at the internationally-known Phillips Eye Institute (PEI) on 22nd and Park Avenue less than a mile from downtown Minneapolis. The PEI is a dedicated eye hospital, the only one in this 5 state region and performs many thousands of eye surgeries a year. Convenient parking is adjacent to the facility. The PEI has a wonderful, highly skilled staff, as well as the latest laser equipment to perform these complex surgeries.

WHAT ARE SOME OF THE MOST DRAMATIC IMPROVEMENTS YOU’VE SEEN WITH PATIENTS WHO HAVE HAD PRK?

The PRK procedures that I’ve performed have allowed many patients to achieve their “dream jobs” of law enforcement, fire fighters, military positions, and military pilots flying jets and helicopters. Many patients can now participate in their favorite activities without the need for contacts or glasses.  I have been very gratified to hear back from the hundreds of soldiers upon whom I performed pro-bono PRK surgery.  Many have told me dramatic stories about how not having glasses or contacts in combat has made their combat experiences safer and in some cases, has been life-saving.

I also have many patients say “This is the best thing I’ve ever done for myself; I wish I had done this earlier,” -and “this is the best money I’ve ever spent.” There have been countless times when I have treated one family member who has been so delighted with the results that they referred me to other family members and friends as well.

I WANT TO CHECK OUT SEVERAL DOCTORS AND CENTERS FOR LASER VISION CORRECTION. WHAT ARE THE QUESTIONS I SHOULD ASK?

  • Who will be doing my surgery?  What are the surgeon’s qualifications?
  • Where will the surgery be done?
  • Who will be doing my pre and postoperative care? Is it a surgeon or a technician?
  • What is the infection rate at the clinic/center?
  • What happens if I have a problem after hours/who will see me?

For questions, please feel free to contact our Refractive Coordinator, Nancy at 612-436-2144 or send an email to: info@eyecare1.com