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Flap-related complications present challenges for surgeons
Surgeons review some common flap-related problems and how to handle them.
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Flap-related problems after LASIK are a concern for any refractive surgeon. Common causative factors are inadequate suction, microkeratome malfunction and corneal curvature anomalies. This article reviews some common complications and ways to avoid or manage them.
Buttonholing of the flap
Buttonholing is one of the more dreaded complications of LASIK (Figure 1), as it is often in the visual axis and may heal with scarring (Figure 2) and loss of best corrected visual acuity. Poor quality blades, inadequate IOP, keratome malfunction and steep corneas are predisposing factors. The procedure should be aborted and the flap should be realigned. The patient may require a deeper re-cut with customized ablation or PRK or PTK with mitomycin-C using a transepithelial approach.
 Amar Agarwal |
Free caps
Free caps are also disastrous complications. The cap should be carefully placed epithelial side down in a drop of balanced salt solution to avoid stromal hydration. Alignment marks on the flap help in identifying the side as well as in realignment. Sufficient time should be given for good flap adhesion (Figure 3). One may secure it either with sutures or a bandage contact lens.
Incomplete or partial flap
An incomplete or partial flap can occur due to a loss of suction midway, any mechanical obstruction to the microkeratome or premature discontinuation of the pass (Figure 4). The surgeon generally has to abort the procedure and make a new flap with a deeper cut 3 to 6 months later. Never attempt to manually dissect as it can lead to loss of BCVA and topographical abnormalities and necessitate procedures such as PTK.
Visually significant striae
If identified, early striae can be treated with flap relifting, hydration (with hypotonic saline) and aggressive stretching for 5 to 8 minutes. In recalcitrant cases, suture placement at the flap edge may be required.
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Images: Agarwal A |
Post-LASIK ectasia
Post-LASIK ectasia may occur in patients with thin corneas, deep ablations or large optic zones. Here, the flap has to be made proportionately thinner. Not maintaining an adequate residual bed thickness causes a long-term increase in the surface parallel stress on the cornea and may lead to post-LASIK ectasia. Progressive ectasia may then need to be treated by deep anterior lamellar keratoplasty, penetrating keratoplasty, intrastromal corneal ring segments or collagen crosslinking with riboflavin treatment.
Epithelial defects
Epithelial defects can occur as a result of poor quality instruments or excessive preoperative anesthetics or in eyes with epithelial basement membrane dystrophy. They are a predisposing factor for infectious keratitis, diffuse lamellar keratitis and epithelial ingrowth.
Epithelial ingrowths
Epithelial ingrowths are seen as a faint white or gray opacity beneath the flap. They are more common after a displaced or torn flap, epithelial defects, or hyperopic or LASIK re-treatment. Treatment by lifting the flap with mechanical removal and irrigation of the surface is indicated if the ingrowth is progressive or extending centrally to the visual axis, associated with stromal melting, distorted flap edge, decreased BCVA or topographical abnormalities.
Summary
Is there a way to avoid all these flap-related problems? The femtosecond laser has recently been hailed as the answer. It produces contiguous plasma bubbles in a raster pattern by photodisruption that expand causing microdelamination of the corneal collagen. But it has not proved to be 100% trouble-free. It gives the surgeon safer and better control to make flaps of any thickness, diameter and with a planar contour from side to side and the ability to place the hinge anywhere. There are also fewer chances for striae, epithelial ingrowth or displaced flap. Complications with the femtosecond laser are rare, and if they occur, the outcome is usually not compromised.
For More Information:
- Amar Agarwal, MS, FRCS, FRCOphth is director of Dr. Agarwal’s Group of Eye Hospitals. Prof. Agarwal is the 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.
- Jairo Hoyos, MD, and Melania Cigales, MD, can be reached at Instituto Oftalmologico Hoyos, Vía Augusta 47, 08006 Barcelona; 34-902-491-902; fax: 34-93-727-63-59; e-mail: jairoca@iohoyos.com.
References:
- Agarwal A, Agarwal A, Agarwal S. Phacoemulsification. 3rd ed. Thorofare, NJ: SLACK Incorporated; 2004.
- Agarwal A. Refractive Surgery Nightmares: Conquering Refractive Surgery Catastrophes. Thorofare, NJ: SLACK Incorporated; 2007 (in press).
- Agarwal A. Handbook of Ophthalmology. Thorofare, NJ: SLACK Incorporated; 2005.
- Agarwal A, Agarwal A, Agarwal S. Four Volume Textbook of Ophthalmology. India: Jaypee; 2000.