Chapter 2- Complications of LASIK Surgery

This will not be a complete discussion of all complications of LASIK or their management.

1. Thin corneal flaps and button holes- this complication is most often caused by inadequate microkeratome suction, poor microkeratome blade quality, steep cornea or microkeratome malfunction. The best treatment is to stop the procedure, replace the flap and in three to four months perform a new keratectomy using a thicker plate.
2. Free corneal flap- the cornea is completely cut off, rather than a hinge being present. The cornea is replaced after the laser treatment and the cornea is air-dried to allow it to stick. The lids are taped shut and the patient is examined the next day.
3. Flap displacement- sometimes after LASIK surgery in an accident or forcible rubbing of the eye, the flap can displace. There are no blood vessels in the flap so as long as three years following LASIK, flap displacement can occur.
4. Recurrent epithelial ingrowth – the top layer of the cornea (epithelium) may grow under the flap. Usually it is self-limited but can grow under the flap into the pupil. If the epithelial ingrowth disturbs vision, the flap can be lifted and the epithelial cells removed. This condition can reoccur.
5. Microbial keratitis- an infection under the corneal flap is rare. Factors such as lid infections, history of herpes of the eye, and long-term steroids on the eye can increase the risk of the infection. The infections can be bacterial or fungal. Prevention is the best avenue with meticulous sterile surgical technique. Treatment is with a variety of topical fortified antibiotics.
6. Corneal melting. The flap can melt with systemic diseases as rheumatoid arthritis or if local disorders of the cornea are present. Steroids, corneal lubricants and a contact lens can help the corneal surface heal.
7. Diffuse lamellar keratitis (DLK)- an unusual inflammation between the flap and cornea. The causes are multiple including debri under the flap and bacterial endotoxins. The treatment consists, in the early stages, of frequent topical corticosteroids. Later, the flap is lifted and treatment with steroids and antibiotics are used.
8. Decentered ablations- the treatment area not being centered can occur in LASIK and Advanced Surface Ablation. The newer Excimer lasers have trackers which help to center the pupil and keep it aligned during the treatment. This complication should be a complication of the past. With wavescan treatment parameters, decentered ablations can be treated with the newer algorithms.
9. Corneal ectasia- thinning of the cornea can occur weeks, months or years after the corneal treatment. The causes of this complication are hard to delineate. One factor may be the residual stromal thickness. After treatment the bed thickness needs to be at least 250 to 300 microns thick. Many surgeons will not operate on a cornea less than 500 microns. Some surgeons utilize Advanced Surface Ablation to prevent corneal ectasia.
10. Night glare and halos- Night glare and halos have been reduced with the newer Excimer lasers whose treatment zone extends to 8 mm. Some patients with a pupil size in the dark of eight or more millimeters are not good candidates for laser surgery.

Reference

Buratto,L. and Brint, S.: Custom LASIK: Surgical Techniques and Complications. Thorofare, N.J.Slack. 2003 p161-287. [book]

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