Coordinated by Bobby Christensen, O.D., F.A.A.O.

therapeutic insights
Coping with Complications
Part one of a two-part series on treating laser vision correction complications.
By Jason Ellen, O.D., Tulsa, Okla.

If laser vision correction is a large part of your practice, or even if you only co-manage a couple of patients each month, you're likely to encounter a post-op complication that requires treatment. I'll discuss two common post-op laser-assisted in situ keratomiluesis (LASIK) problems and the levels at which they require treatment.

The truth about ingrowth

Ingrowth of the corneal epithelium into the LASIK flap interface occurs in roughly 1% to 2 % of cases. Many of these epithelial invasions occur quickly and quietly before the flap seals and cause neither visual nor physical complications.

Infrequently, the advancing epithelial sheet, or nests, continue to invade the interface, threatening the patient's vision and flap integrity. Identifying areas of ingrowth early and monitoring them frequently will ensure proper and timely management. Here's what you need to know:

It's usually easy to detect ingrowth with a normal slit lamp exam. Have the patient look down or, if he has a narrow palpebral fissure, raise his upper lid to check the superior edge of the flap.

As with many corneal conditions, retro-illumination through a dilated pupil gives the easiest view of the advancing margin of the ingrowth.

Treating ingrowth

Treating ingrowth involves lifting and removing the epithelial sheet. Once the surgeon lifts the flap, he peels the epithelial sheet off, then scrapes, wipes clean and irrigates the corneal stroma and underside of the flap. He then repositions the flap and smoothes it (especially the edges) to form a better adherence and to prevent recurrence.

In severe cases or with recurrent ingrowth, surgeons may use ~5 µm of phototherapeutic keratectomy (PTK) on the stromal bed and the underside of the flap to kill any remaining cells. As an alternative to PTK, surgeons may apply a low-percentage alcohol solution to the exposed stroma for 15 to 30 seconds to kill any remaining epithelial cells and to prevent further nesting. In cases with multiple ingrowth occurrences, a surgeon may suture the flap edge to achieve a tight apposition.

If left untreated, ingrowth can lead to severe flap melt, which may then require complete flap removal to regain visual capacity. In any case, close monitoring on weekly schedules for the first month may prevent highly aggressive areas of ingrowth.

Diffuse lamellar keratitis (DLK) is another common complication you should know about. Here are some facts.

Getting to know DLK

Experts believe that DLK, or Sands of the Sahara, is a type-IV hypersensitivity response to a foreign material or substance within the flap interface. The term "Sands" describes the white blood cells that invade the interface and position themselves to give a "sand dune" appearance. It's usually detected near the flap edge on the 1-day post-op exam.

In many cases, the cause of Sands is hard to determine. It's usually sporadic in its presentation from one patient to another, but surgeons have reported multiple cases of Sands from a single surgical day. In multiple cases, surgical facilities can sometimes trace the cause of Sands to the deposition of dead bacterial protein coats deposited on the corneal stroma.

Autoclave sterilization of surgical instruments kills bacteria, but their ruptured protein coats may remain on the instruments and deposit within the interface during the lamellar dissection. Detergent residue, epithelial defects, flap dislocations or trauma can also trigger mild to moderate cases of DLK.

Managing DLK

The key to managing DLK is diagnosing the condition early and initiating early treatment. Treat mild cases with a mild steroid every 1 to 2 hours and taper after resolution. Treat moderate cases with a strong steroid every hour while awake with a 2- to 3-week taper after initial signs of improvement.

Check intraocular pressure to watch for steroid responders. Severe (Grade 3) Sands may require surgical intervention and/or oral or subconjunctival steroids to reduce the inflammatory response. Surgeons may use 5 µm of PTK on the stromal bed after irrigation to eliminate the offending agent.

More to come

You've seen two common complications that may arise following laser vision correction. Hopefully this information will better guide you in the future when you find yourself co-managing a patient suffering from one of these complications.

Next month I'll talk about two more laser complications -- dry eye and striae.

Dr. Christensen has a partnership practice in Midwest City, Okla. He's a diplomate in the Cornea and Contact Lens Section of the American Academy of Optometry. He's also a member of National Academies of Practice.