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Surgeons need to recognize and know how to avoid LASEK complications
LASEK pioneer Massimo Camellin, MD, discusses how to avoid turning LASEK into PRK and how to handle other complications.
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Introduction
The LASEK technique has shown few complications, some of which are also common in PRK. For this reason, it is important to recognize that some LASEK surgeries may become PRK if the flap is lost during the first few postoperative hours. If the surgeon is not that skilled, he will believe that he has accomplished a LASEK and will be unable to understand why his results are like those of a PRK. My special guest in this column is LASEK pioneer Massimo Camellin, MD, of Italy to explain how to handle LASEK complications.
Amar Agarwal, MS, FRCS, FRCOphth
 Amar Agarwal |
Epithelium management is the first step toward a good LASEK, but despite its relative feasibility, the technique requires some tricks that must be taken into account to avoid postoperative pain and flap loss during the early hours. The use of a toothed trephine means that every epithelium can be pre-cut, independently of its thickness. However, when the instrument is rotated, be careful not to rotate the globe; otherwise, the effect is to create a circular series of notches that do not lead to the same result of increasing the alcohol flow under the epithelium itself. In some cases, however, the solution can nevertheless pass the epithelium barrier, but the problem is to allow its flow, as much as possible, to detach even stubbornly attached epithelium. When one starts to rotate the trephine aid with a fixation ring, it is important to pay attention and make sure that the instrument moves at least 10° in comparison to the globe. Do not exceed this safety value, as it risks the creation of a hinge that is too small, thereby increasing the risk of flap loss.
Alcohol management. The well contains an alcohol solution, and leakage onto the conjunctiva must be avoided. An adapted well has been designed with a double edge that works better both in keeping the eye firm and containing the solution. When the correct amount of time (20 seconds) has elapsed, do not take the well away before having dried the contents and rinsing it with diclofenac.
Having followed this rule, make sure that no contamination of the conjunctiva has occurred.
Unfortunately, despite best efforts, some patients move their eye during alcohol exposure, and there may be some leakage onto the conjunctiva, which will immediately feel painful. At this point, abundantly rinse with diclofenac, and if exposure has been too short, apply alcohol into the well again.
Flap-making. Starting detachment of the flap edge is the best way to begin flap-making and also serves to understand how well the flap is attached. If strong resistance is perceived, stop and reuse alcohol for 5 to 10 seconds more. This maneuver increases the alcohol flow because now there will be a real groove on the periphery of the flap, and 5 to 10 seconds is enough to greatly increase the detachment. The more adherent the epithelium, the higher the pressure on the spatula must be, which must be used vertically at its shortest side. Sometimes, tears may occur, but the worst complication is a hinge tear because of the drawback of making it difficult to recognize the right side of the flap when it has been rolled back. It is always better to manage the flap with two rounded spatulas, and in this unfortunate case, the surgery can be saved by operating calmly.
Having lost the hinge, one must try to increase flap stability, and this can be achieved by drying the flap for 2 minutes at the end of the procedure before fitting the contact lens.
In these cases, it is a good idea to brush the surface with mitomycin-C 0.01% before rolling the flap back.
If the patient experiences pain on the first day, applying crushed ice several times is useful. There is an important surgical step in pain prevention, which is not well understood, and that is flap squeezing. At the end of the procedure, after the lens fitting, I use an applanator to squeeze out all fluid from underneath the flap itself (Figures 1 and 2). This has the double purpose of increasing flap stability for a vacuum mechanism and reducing nerve-end stimulus due to flap movements (Figure 3).
Flap tear. In LASEK, more than in PRK, the epithelium has good adherence only after a few months, due to the poor inflammatory reaction. Unfortunately, during the first postoperative months, patients can damage flap integrity with unwanted contact (Figure 4).
| Squeezing fluid from under the flap avoids contact between nerve tips and the flap. | |
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Images: Camellin M |
Septic infiltrations. Septic infiltrations seem to affect the peripheral area of the cornea where the stroma is exposed because it is not protected by the epithelium. We have had a high number of peripheral infiltrations with hydrogel lenses, which appear characteristically rounded, small and deep.
Epithelium thinning. Epithelium thinning complications more frequently appear close to the central area. For reasons still unknown, the epithelium can be slow to re-grow, and we suspect the origin is poor viability in the inner layers of the epithelium itself. After a LASEK procedure, the epithelium is renewed and the old layer goes away in 3 or 4 days; in some cases, the viability is so good that the new one joins the old instead of slipping under it. As we know, the inner layer has the ability to re-grow 8 to 10 times, and wound healing in these cases follows another path. The substitution of cells belonging to the old flap is progressive, but taking into account this process is physiologically slow in that it can oppose the movement of the newly born limbal cells toward the center. Fortunately, this paradox is rare, but the surgeon must immediately recognize it, and suspending steroids and increasing artificial tears is worthwhile. Patient refraction in these cases is hyperopic and often with an irregular astigmatism, but progressively it reaches the target in 1 or 2 months without consequences.
Inclusions under the flap. Sometimes debris or small particles of tissue can be trapped under the flap, but this has not shown itself to be a real problem. During flap renewal, all these unwanted impurities are expelled, and none of them can be detected within a month. Therefore, washing under the flap at the end of the procedure is not useful.
Under- and overcorrection. An immediate hypo- or hypercorrection is obviously due to laser failure and not to the re-growth of epithelium or stroma. If this occurs, it is worthwhile treating it within 2 months, as in this period it is easy to detach the new epithelium and correct the remaining defect. In this case, I always use MMC 0.02% for 2 minutes, as the keratocytes can be active due to re-operation and the risk of haze is significant. We always prefer to use alcohol even if it is possible to detach the epithelium without it because patients treated without it have shown more pain.
For More Information:
- Amar Agarwal, MS, FRCS, FRCOphth is director of Dr. Agarwal’s Group of Eye Hospitals. Prof. Agarwal is author of several books published by SLACK, Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery, and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; e-mail: dragarwal@vsnl.com; Web site: www.dragarwal.com.
- Massimo Camellin, MD, can be reached at Sekal Microchirurgia Rovigo, Via Dunant 10, Rovigo 45100, Italy; phone/fax: 39-425-411357; e-mail: cammas@tin.it; Web site: www.lasek.it.
References:
- Agarwal A. Handbook of Ophthalmology. Thorofare, NJ: SLACK Incorporated; 2005.
- Agarwal A. Refractive Surgery Nightmares. Thorofare, NJ: SLACK Incorporated; 2007 (in press).
- Agarwal S, Agarwal A, Agarwal A. Four volume textbook of ophthalmology. India: Jaypee; 2000.