For many patients with irregular corneas, PRK (or photorefractive keratectomy) is preferred to LASIK for the correction of Nearsightedness (myopia), Farsightedness (hyperopia), and/or Astigmatism.
Unlike LASIK, PRK doesn't require an incision in the cornea. For someone with unusually thin corneas, for example, this is a huge advantage since the long-term structural integrity of the eye is not compromised by PRK. During PRK, the thin outer membrane of the cornea, called the epithelium, is loosened and then removed, exposing the surface of the thick central part of the cornea, called the stromal bed. The laser then reshapes the stromal surface (thus the PRK moniker, "surface ablation") according to the patient's vision error.
The entire process takes just minutes to perform. The epithelium then heals over the exposed surface during the following several days, during which time the eye can experience varying degrees of irritation. Although vision is typically improved immediately following the procedure, maximum vision recovery can take several weeks.
While the PRK post-op recovery is longer than LASIK, this is a relatively small price to pay to enjoy visual outcomes comparable to LASIK, but without the unique risk that LASIK poses for some patients. In fact, PRK outcomes are considered so good, that the U.S. Navy has recommended the procedure for naval aviators. In a major PRK study undertaken by the Navy, 95% of pilots and flight crew achieved 20/20 or better, 80% 20/16 or better, and 50% 20/12.5 or better (20/12.5 is far superior to 20/20)!
In fact, Zak Keasey, a San Francisco 49ers running back, now sees much better than 20/20 after his Wavefront PRK with Dr. Hyver. You can follow Zak through his Wavefront PRK pre-op, surgical, and post-op experiences in Dr. Hyver’s new DVD. Order your free copy here, or watch on-line or download the video file in our LASIK Lounge.
The LASIK Lounge also contains an audio program featuring Wavefront PRK patient, Heidi B., one of Dr. Hyver’s patient counselors, who discusses her pre-op, surgical, and post-op experiences with PRK. A practical and articulate overview: well worth the listen.
PRK with Dr. Hyver has enabled our patients to substantially improve the quality of their lives. For more information on PRK, here's some answers to frequently asked questions:
WHY PRK?
What's the difference between LASIK and PRK?
LASIK and PRK are procedures; that is, they are different surgical methods by which Dr. Hyver prepares the eye to receive the laser. In LASIK, he creates a corneal flap — the hallmark of LASIK — then lifts the flap, treats the underlying tissue with the laser, and restores the flap, whereupon it heals. In PRK, he instead removes the cornea's outer membrane, called the epithelium, applies the laser to the newly-exposed surface, over which a new layer of epithelium then grows in the days following the treatment.
Why wouldn't I qualify for LASIK?
Because the thickness and/or shape of your cornea may be unusual, and therefore a surface treatment like PRK, that doesn't require a corneal flap as in the LASIK procedure, is apt to prove a safer long-term solution.
What's the difference between Classic PRK and Wavefront PRK?
The terms Classic and Wavefront refer to information technologies (i.e., data, software and firmware) that control where and how the laser operates on your eye. Because Wavefront technology provides a more accurate and comprehensive measure of your vision error -- and thus a more precise path for the laser to follow -- Wavefront PRK patients are apt to enjoy better distance vision, day and night, than Classic PRK patients.
What's the likelihood that after PRK, I'll see 20/20 or better, free of my contact lenses and glasses?
A patient's visual outcome is a function of many variables, including age, prescription type and size, best-corrected vision with glasses prior to surgery, and corneal healing profile. With Wavefront technology and Dr. Hyver's extensive PRK experience, the vast majority of our PRK patients now achieve 20/20 or better.
Will I experience vision disturbances at night after PRK?
Starbursts, halos and other night time vision artifacts occur when light is scattered from the peripheral edge of the laser zone through a pupil which is enlarged due to dim illumination. The larger the night time pupil and the larger the treated prescription, the more chance that one will experience these side effects and the more obvious they might be. Dr. Hyver understands this effect, and will design your treatment to minimize the prospect of night vision disturbance. Regardless, all patients during the initial 6 month post-operative period may experience some degree of night disturbance until their corneas are completely healed.
Can PRK correct both distance and reading vision?
Patients over the age of 40 typically experience some degree of presbyopia, or “aging eyes,” that causes a loss of reading vision. Presbyopia is caused by a stiffening of the lens, the internal focusing element of the eye. Since laser vision correction, including PRK, only operates on the cornea, the external focusing element of the eye, we can't directly address the problem of the aging lens. Instead, we offer monovision, wherein Dr. Hyver corrects one eye for distance, and produces a target amount of nearsightedness in the other eye for reading purposes. To learn more about monovision and your reading options, click here.
PREPARING FOR PRK
How do I prepare for PRK?
One of Dr. Hyver's patient counselors will review your pre-operative instructions with you. Generally, if you wear contact lenses, you'll need to remain out of them for a specific period of time. You'll also need to use a combination of over the counter and prescribed medications, including antibiotic drops, over a specific timeframe and frequency.
Will I need to arrange to have someone drive me home after PRK?
Yes. If you're not able to arrange for a ride, please call us and we'll help coordinate this.
WHAT TO EXPECT DURING PRK
What can I expect when I arrive for my PRK?
After you check-in, we'll perform some additional tests on your eyes to help refine our understanding of your vision error. You'll then be seated in an exam room, shortly after which a technician will take you to the laser suite.
Can I get a payment receipt to submit to my "flex" pre-tax health reimbursement account administrator?
Yes, just request this when you pay at check-in.
What can I expect during the procedure itself?
You can expect several steps to occur, first to one eye and then to the other. And because your eyes will be anesthetized, you will experience little or no discomfort throughout the entire process.
- After prepping your eye, Dr. Hyver will use a special tool to remove a small area of the epithelium (i.e., the ultra-thin outer membrane of the cornea).
- Dr. Hyver will then apply the laser, programmed to treat your specific vision error, to this exposed area. The laser will operate for about 30 seconds, and you will not feel it.
- After the laser treatment, Dr. Hyver will apply a special contact lens over the treated area to protect it during the initial healing period. We'll remove the contact lens at your first post-op exam.
After your PRK procedure, a technician will take you to an exam room, where one of the doctors will check your eyes through the microscope to ensure everything is in order. After donning a pair of sunglasses that we'll give you, you're free to leave with your ride.
WHAT TO EXPECT AFTER PRK
Between one and three days after your PRK, you can expect some discomfort, potentially including irritated, burning eyes; light sensitivity; tearing; and swollen eyelids. Most of this discomfort can be attributed to the removal of the epithelium, which acts as a natural barrier between your eye and your environment. However, keep in mind that some patients experience little or even no discomfort during this time. We'll provide you with a prescription for pain relief medication and other pain prevention support.
Between four days and one week after your PRK, your vision may be blurred and hazy, but the discomfort of the first few days should be over. You should also be seeing equal to or better than 20/40, the minimum acuity for driving vision in California, and should be back to your normal lifestyle by this time. During this period, we will remove the protective contact lenses that Dr. Hyver placed on your eyes during your surgery.
Between one and three months after your PRK, the new growth of epithelium over your treatment area will smooth and even out, producing clearer and clearer vision.
Between three and six months after your PRK, your new vision should be stable, and you should be enjoying vision results equal to or in some cases better than patients with comparable prescriptions who had LASIK instead.
Why is the recovery period longer than that of LASIK?
Because LASIK employs a corneal flap that essentially preservers the epithelium layer when the flap is restored over the treatment area. It's the removal and absence of the epithelium — a necessary step in the PRK process — that creates the discomfort during the early healing period, as well as the longer vision recovery.
How soon can I fly in an airplane?
Altitude has no effect on the vision or the healing of the eye after PRK. So, you can actually fly the next day if you like. However, be aware, that the air blowing from the vents above you may make your eyes feel more dry. Just bring your teardrops with you.
Once my recovery is complete, how long will my new PRK vision last?
Laser vision correction, including PRK, is designed to be permanent and durable. After more than two decades of experience with PRK, there's no evidence that its effectiveness degrades over time.
