"Wrinkles" After LASIK - How Can They Be Treated?
LASIK is the most popular treatment today for the correction of myopia, hyperopia, and astigmatism, with over a million procedures performed each year in the US. Advantages of LASIK over the older PRK include less postoperative pain and a more rapid recovery. However, as with any surgical procedure, complications can still occur. In this article I will focus on wrinkles, or flap striae, one of the most common LASIK complications. Wrinkles occur when folds form on the corneal flap that is created during LASIK.
The incidence of flap striae in most refractive surgeons' offices is usually under 5%, but striae are nonetheless one of the most common problems associated with LASIK.
In order to prevent striae from occurring, the refractive surgeon must take care when creating the flap. After reshaping the exposed cornea with an excimer laser, the surgeon must reposition the corneal flap back to its original location over the stromal bed (the portion of the eye that lies directly beneath the corneal flap), usually using sponges and forceps. If any wrinkling or misalignment occurs, flap striae may form.
When and what type of striae should be treated?
Immediately after LASIK, some residual striae are often visible but may completely disappear the next day. Striae outside the visual axis are relatively harmless. Only striae in the visual axis that cause astigmatism or affect best-corrected visual acuity (BCVA) should be treated. Folds, in contrast, are thick and wrinkled and need to be treated as soon as possible.
If flap striae form, they should be identified on the first postoperative day and, when visually significant, should be treated as soon as possible. If significant striae are not treated within the first two weeks after surgery, they may become imbedded in the corneal flap tissue, making them difficult to remove.
Causes and predictors of striae formation
Striae can form in a number of ways. They are more common in patients over age 40, and in high myopes because of the ‘tenting affect,' which is caused by the greater depth of tissue ablation needed to reshape the cornea. Greater ablation can alter the original flap-stromal bed relationship, creating a tent when the flap is placed back onto the stroma. Striae can also form by misalignment of the corneal flap after flap replacement, by photophobia (abnormal sensitivity to light), or by movement of the corneal flap during the first postoperative day by rubbing, blinking excessively, or squeezing the eye due to pain.
Techniques that minimize flap manipulation may reduce the incidence of striae.
Detection of striae
While the causes and predictors may prepare the LASIK surgeon for what to expect postoperatively, early detection of striae in any patient is still crucial. Flap striae can occur within the first hour after LASIK, so refractive surgeons should take measures to detect striae as soon as possible. The first step is to examine the patient at the ‘slit-lamp,' a lighted microscope that allows the doctor to examine your eye under high magnification. A corneal topography should also be performed as part of every postoperative checkup. If visual acuity is not near 20/20, if it is worse than preoperative acuity, or if astigmatism is present, flap striae or wrinkling may be the cause.
The presence of wrinkling or striae must then be confirmed to indicate if flap manipulation is necessary. The traditional method is to dilate the pupils and examine the cornea under a slit-lamp.
A new method of assessing the presence of striae is examining the tear film after instilling fluorescein in the patient's eye. The tear film created after blinking is examined at the slitlamp with a cobalt filter. Uneven pooling of the tear film after blinking is an indication of flap striae.
Early detection of striae is crucial for successful treatment. Older people, high myopes, those with epithelial defects, and those with eye trauma tend to get striae. Patients who have thin, torn, or incorrectly sized flaps, those who receive nasal instead of superior hinged flaps, or those who have flaps that are excessively manipulated also tend to get striae.
There is no one universal method for treating striae. Those striae that occur in the visual axis can be approached by refractive surgeons in many ways depending on the type and severity, as well as the amount of time they took to detect. Methods such as re-floating the flap, using hypotonic solution or collagen punctal plugs, ironing out the wrinkles with a special instrument, removing the epithelium, suturing the flap, and using a bandage contact lens are the more common measures that refractive surgeons take to remove striae.
Reticular micro-striae - reticular micro-striae need to be treated with a bandage contact lens, punctal plugs, or lubrication medicine. If these striae still persist after two weeks of treatment, then they should be treated like the other types of striae.
Pseudo-striae and stromal folds
To treat pseudo-striae and stromal folds detected within two weeks, most refractive surgeons carefully dissect the corneal flap along the edge, flip it back, and hydrate it with a filtered hypotonic saline mix. The mixture allows the flap to expand and become more malleable to facilitate the removal of striae. The flap can then be floated and stretched into position to adhere back to the stromal bed, which takes about three to five minutes. Stretching is done with blunt forceps on the epithelial surface of the flap by pushing the flap edges gently but firmly away from the central cornea (the area of the deepest excimer ablation). This allows the flap to fill in the ablated stromal bed.
Some doctors remove a small layer of epithelium and then use a bandage contact lens to reduce the occurrence of further wrinkling. This has been successful for patients with epithelial defects, as well as for thin or perforated flaps. If the striae appear to be imbedded, a 4mm or 5mm layer of epithelium can be removed, the striae can be stretched out, and a bandage contact layer can be applied.
New instruments and methods
Some refractive surgeons today have started moving away from using saline solution. Instead they stretch the striated flap for about 8 minutes with forceps. Some use special ironing and stretching instruments such as Rhein's Johnston Applinator, the Tress Kornmehl Press, the Pineda LASIK Iron, Acorn's Donnenfeld Striae Removal Spatula, or the Herzig Compressor.
A new method involving the use of sutures for treating striae is also being tested, and thus far has proven to be successful for treating long-standing or persistent striae, as well as dislodged corneal flaps. Some doctors utilize five interrupted sutures to treat these striae.
Patients should recognize that LASIK is a surgical procedure. They should choose their LASIK surgeon carefully, because the best-trained LASIK surgeons know how to successfully treat the complications that sometimes arise. Choose a LASIK surgeon who is fellowship-trained in refractive surgery, attended top medical schools, residency programs, and fellowship training programs, and has performed at least 2,000 LASIK procedures. Flap striae and other LASIK complications are very treatable—but only if your refractive surgeon knows what he or she is doing!
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2. Rabinowitz YS, Rasheed K. Fluorescein test for the detection of striae in the corneal flap after laser in situ keratomileusis. Am J Opthalmol 1999; 127: 717-8.
3. Muñoz G, Alió JL, Pérez-Santonja JJ, Attia WH. Successful treatment of severe wrinkled corneal flap after laser in situ keratomileusis with deionized water. Am J Opthalmol 2000; 129: 91-2.
4. Lam D, Leung ATS, Wu JT, Cheng ACK, Fan DSP, Rao SK, Talamo JH, Barraquer C. Management of severe flap wrinkling or dislodgement after laser in situ keratomileusis. J Cataract Refract Surg 1999; 25: 1441-7.
You can E-mail Dr. Chynn your questions about LASIK and he will answer them all personally, without charge, and usually within 2-3 days! E-mail Dr. Chynn at: firstname.lastname@example.org. You can also visit his website for more information about LASIK.
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