By Alex Archibald, OD
PCLI—Great Falls, MT

LASIK has had a profound effect on how optometric physicians practice and can boast a high success rate in helping people achieve the visual freedom they desire. The majority of LASIK patients are happy with their new ability to see. But, as with any surgical procedure, there is potential for complications. Even when surgery goes well, problems can show up later.

Let’s briefly review three possible complications. If LASIK is a significant part of your practice, you may have managed one or all of these problems:

1. Corneal striae
2. Diffuse lamellar keratitis (DLK)
3. Epithelial ingrowth

Striae are typically are fine wrinkles in the LASIK flap, but occasionally more prominent folds are encountered. They are usually the result of a shifted flap related to mechanical issues such as eye rubbing or inadvertent bumping of the eye. Severe striae can cause ghosting and poor quality vision. Striae are best visualized by indirect slit lamp illumination or by retro-illuminating the cornea. Fluorescein dye may help identification of mild cases.

Causes:

• Inappropriate manipulation of the flap
• Internal stresses of the flap
• Unstable flap
• Trauma

Mild Cases:

• More common in patients with a high myopic correction because the deeper laser ablation results in a stromal bed that is slightly flatter than the curvature of the corneal flap.
• Usually not visually significant
• No treatment required unless BCVA is decreased or a gape at the flap edge exists.
• Simply evaluate and document

Severe Cases:

• Fairly uncommon
• BCVA is decreased due to involvement of the central cornea.
• Refer patient to surgeon for flap refloat.

DLK is an inflammatory sterile reaction to antigens in the corneal interface. A haze of white blood cells is seen extending inward from the corneal limbus with no specific pattern. It can involve the peripheral or entire cornea. When most prominent, slit-lamp examination shows fine, white grainy cells that look like waves of sand; hence DLK has been nicknamed Sands of the Sahara. This condition can be difficult to diagnose in the immediate post-op period.

Cause:

• Although a number of theories have been researched and discussed, the specific cause is unknown.
• Patients with allergies tend to be the most vulnerable.

Signs and Symptoms:

• Usually 1-6 days after surgery a haze appears in the corneal interface extending from the limbus with associated bulbar conjunctival injection.
• At the time of earliest onset, patients may not complain of discomfort and will often be experiencing good vision.
• Discomfort, blurred vision, foreign body sensation, and sensitivity to light often develop in untreated eyes.

Treatment:

• A regimen of frequent topical steroids is usually effective; typically 1 drop every 1 to 2 hours.
• Corneal inflammation should begin to resolve within 1 to 3 days, although treatment for a few weeks may be indicated.
• If inflammation does not begin to resolve after 5 days, the patient should be referred back to the surgeon.
• If significant inflammation persists after 5 to 7 days, the flap will occasionally be lifted and the interface cleaned.

The sooner DLK is diagnosed and treated the better the prognosis. Delayed treatment can result in scarring.

This condition occurs when epithelial cells migrate under the edge of the LASIK flap and grow towards the visual axis. Epithelial ingrowth is typically detected within 1 to 2 weeks of surgery. Peripheral cells may advance about 1 mm under the flap edge before it seals. They usually appear as an irregular white line concentric with the flap margin and are considered “non-aggressive”. The white line is a good sign indicating stability.

Cause:

• Patients with dry eye problems or poor corneal flap adherence have greater chance of epithelial ingrowth.

Signs and Symptoms:

• Ingrowth initially presents as a translucent haze along the flap margin, becoming more opaque (whitish-greyish) with time.
• As progression occurs, patients may report worsening vision, due to increasing astigmatism, and discomfort not relieved with artificial tears.
• Nests of epithelial cells can appear as a peninsula-shaped, whorl-like opacification. Although these groups of cells may be non-progressive, they should be monitored for development of patient symptoms or compromised corneal health.

Treatment:

• No treatment is required if cells are stabile and not visually significant.
• Surgical intervention is generally needed in the few cases where ingrowth progresses further than 2 mm and is either affecting vision or integrity of the flap.

Epithelial ingrowth is the most common complication after uncomplicated surgery. Although aggressive epithelial ingrowth that requires intervention is relatively uncommon, ensuring a healthy corneal surface before LASIK may be the best way to limit the risk of this condition.

Although uncommon, these complications can present problems to patients’ vision and ocular health if left untreated. In order to give the best and most effective care, it is important to not only be familiar with these possible complications, but to be aware of the treatment options—and understand when surgical management is needed.