PRK and LASEK: MANAGING PAIN
Surface ablations may have a bright future, but minimizing discomfort will be essential.
Some surgeons now believe that surgery on the corneal surface will provide the most accurate results when they perform customized ablations. However, procedures such as photorefractive keratectomy (PRK) and laser-assisted subepithelial keratectomy (LASEK) have traditionally been perceived as more painful than LASIK.
Here, two experts share strategies they use to minimize patient discomfort following surgery.
Post-PRK Pain Management
By Sylvia W. Norton, M.D.
Because excimer laser corneal refractive surgery excises part of the cornea, it cuts and disrupts many corneal sensory nerve fibers. During PRK, free nerve endings are shredded; during LASIK, nerves are shredded below the surface in the corneal stroma. This disturbance and excision of sensory nerves is the source of the significant pain that can be associated with laser refractive surgery. As a result, a key part of successful surgery is minimizing unnecessary patient discomfort. (Note: Marketing and advertising have led patients to believe that PRK is much more painful than LASIK, but there's no evidence to support this claim. Both PRK and LASIK patients often have pain during the first 24 hours post-op.)
Here, I'd like to share a number of preoperative, intraoperative and postoperative measures you can take to minimize patient pain during and after PRK.
I recommend taking these steps before surgery:
Educate the patient. Not having a clear understanding of what the procedure involves will cause apprehension, and that can increase perceived pain. In contrast, a good pre-op surgical orientation will reduce anxiety and pain perception.
As part of the informed consent process, let the patient see the surgical suite and the excimer laser before the day of surgery. Go through the procedure step by step. Explain that the patient lies on his back while topical anesthesia is instilled, to eliminate all intraoperative pain, and that a nonpainful lid speculum will be put on the patient's eye.
Provide meds before surgery. For the best control of postoperative PRK pain, give the patient an oral analgesic (such as Tylenol with Codeine #3, 800 mg of ibuprofen or an oxycodone/acetaminophen combination such as Percocet) along with diazepam or a muscle relaxant, just before surgery. Patients report less pain when the analgesic and muscle relaxant are given before surgery instead of immediately after surgery or when postoperative pain begins.
Pain control intraoperatively and immediately post-op
The standard for pain control during PRK is to apply three drops of tetracaine or proxymetacaine hydrochloride (Alcaine) topically to the operative eye at the time of surgery.
Once surgery is complete:
Try bandage contract lenses. These can be put on the eye immediately after PRK surgery. But keep in mind:
- Lenses that fit well will reduce pain, but lenses that move excessively can aggravate the corneal surface and increase pain.
- The bandage lenses must stay in place until complete re-epithelialization occurs. Left in for at least 24 hours after epi-thelial closure, they can prevent painful epithelial re-openings.
- Eye patches appear to be less effective than bandage contact lenses for controlling post-PRK pain.
Use topical pain medication. Immediately following PRK, have the patient use nonsteroidal anti-inflammatory (NSAID) drops and topical steroids to control pain.
- NSAIDs such as ketoralac tromethamine ophthalmic solution 0.5% (Acular) and diclofenac sodium 0.1% (Voltaren Ophthalmic) have been observed to reduce corneal pain from laser refractive surgery. These drops should be used no more than four times a day to prevent sterile corneal infiltrates.
NSAID use should be discontinued when the pain stops.
- Topical steroids like fluorometholone ophthalmic suspension, USP 0.1% (FML) can be administered four times a day for at least the first month to control inflammation and aid healing. I taper them one drop each month.
"Some patients believe that PRK is much more painful than
LASIK, but both PRK and LASIK patients often have pain during the first 24 hours post-op."
Pain control during the following weeks
After PRK surgery, pain usually ceases once the corneal epithelium closes completely. Meanwhile:
Get the patient to rest. Resting for 48 hours after surgery will reduce pain, but most refractive surgical patients won't allow time to recuperate unless you tell them to. Also, tell them to resist the temptation to engage in normal vision activities such as reading and watching television immediately after the surgery. Their (temporarily) imperfect vision can cause stress and apprehension, which will exacerbate corneal pain.
Treat dry eye syndrome (DES) aggressively. At least 50% of PRK candidates experience some discomfort from DES -- burning, stinging or foreign body sensation -- during the weeks or months following PRK. They may exhibit lagophthalmos during both day and night.
- Tears, humidifiers and punctum plugs will help to alleviate the symptoms of DES.
- Having the patient use moisture goggles during the day and night for the first 48 hours after PRK, and then nocturnally, will reduce DES in patients who display incomplete blinking. Use of goggles at night should be continued for at least 3 months post-PRK if nocturnal lagophthalmos is present; otherwise the patient will notice morning discomfort.
Getting to the happy ending
Of course, patients will experience different degrees of discomfort after PRK. Nevertheless, applying these measures can significantly reduce pain and make it a less memorable part of the visual rehabilitation process. Then patients can focus on what really matters: their new and improved vision.
Dr. Norton is director of the Jerva Eye Laser Center in Syracuse, N.Y. She's also an adjunct professor at the University of Ottawa Eye Institute and was an FDA principal investigator for PRK from 1991 to 1996.
Post-LASEK Pain Management
By Lee Shahinian, Jr., M.D.
Laser-assisted subepithelial keratectomy (LASEK) has three advantages over LASIK:
- All complications associated with the microkeratome and stromal flap are eliminated.
- LASEK can be performed in cases where LASIK may be contraindicated.
- Some preliminary evidence suggests that surface ablation procedures such as LASEK may give more accurate results than LASIK for customized wavefront-guided ablations.
Nevertheless, patients undergoing LASEK may experience more postoperative pain than LASIK patients. It's important that we address this problem, both for the comfort of the individual patient and to promote wider acceptance of LASEK.
Keeping discomfort under control
Here are a number of steps you can take to help reduce post-op pain following LASEK.
Manage patient expectations. We repeatedly warn patients that they may experience some pain during the first 48 hours, but that the amount of pain experienced varies widely from patient to patient. About 30% of patients have little or no sensation, 50% have moderate pain and 20% are quite uncomfortable. Also, some patients will have pain the first night, while others may be comfortable for 24 hours and only then begin to experience significant discomfort.
Make sure patients understand the reason for the pain. LASEK patients will talk about their experience with their friends, family and co-workers, many of whom will have had LASIK and experienced little or no pain. LASEK patients need to understand the reason for the difference.
When contrasting LASEK with LASIK, I explain to the patient that because I'm working closer to the surface with LASEK, more nerve endings are temporarily exposed. I make the analogy of scraping a finger versus cutting it. While the former is temporarily more uncomfortable, there is actually more potential for harm with a cut than with a scrape.
Offer extra support. I routinely give my LASEK patients my home and pager telephone numbers and encourage them to contact me at any time if they need help.
Prescribe appropriate medications. I recommend:
- At the time of LASEK surgery, have the patient take 400 to 600 mg of oral ibuprofen. Postoperatively, I instruct the patient to take ibuprofen 400 mg q.i.d.
- I give the patient two Vicodin tablets to take for severe pain, one every 4 to 6 hours. This can be helpful if, for example, the patient has trouble sleeping the first night.
- I avoid prescribing more narcotic pain medication (which often leads to nausea and vomiting) and NSAID drops, because of the possibility of corneal infiltrate or melt.
- Ice packs applied to the temple can be helpful.
- I have the patient use both a fluoroquinolone and steroid q.i.d., post-op. (The latter may play some role in controlling pain.) The patient stops or tapers the steroids after 4 days, depending on the refractive situation. I also instruct the patient to use preservative-free artificial tears every hour unless the eye is already watery.
- Dilute topical anesthetic drops can help control pain. Dilute either tetracaine 0.5% or proparacaine 0.5% to 1/10th the normal concentration (0.05%) using artificial tears. At this
subanesthetic concentration, the drops will have an analgesic effect. Note: Don't dilute tetracaine minims containing
chlor-butanol; chlorbutanol is incompatible with soft contact lenses.
These drops can be applied as often as every 30 minutes without numbing the cornea or inducing corneal toxicity. I explain to patients that the drops may give only partial relief; they'll still be aware of an abnormal sensation in their eye, like having a pebble in your shoe instead of a thorn.
Choose the right bandage contact lens. This is important for maintaining patient comfort:
- The Bausch & Lomb Soflens 66 F/M works well. It doesn't come in plano power, so I usually select a -0.50D lens.
- More recently, I've used the CIBA Vision silicone hydrogel lenses, which also seem to work well.
"When contrasting LASEK with
LASIK, I make the analogy of scraping a finger versus cutting it. While the former is temporarily more uncomfortable, there is more potential for harm with a cut than with a scrape."
The contact lens should be left in place for 4 days postoperatively, and the operated eye should be covered with a shield at night to prevent accidental rubbing.
Have patients limit their activities during the first 2 days postoperatively. In my experience, patients report less pain during the first 2 days if they avoid going out in the evening for entertainment, going on excursions, doing aerobic exercise or gardening -- no matter how good their eyes feel.
The future looks bright
LASEK is emerging as a potentially important tool in our refractive armamentarium. If you use these strategies, you should find your LASEK patients having much less trouble with post-op discomfort. That can only be good -- for your patient, your practice, and the future of LASEK.
Dr. Shahinian is in private practice in Mountain View, Calif. He founded and directed the Laser Vision Correction Program at Stanford University Medical Center from 1993 to 1996, and is currently on the clinical faculty at both Stanford and the University of California Medical Center in San Francisco. You can reach him at (650) 969-7733, or via e-mail at email@example.com.