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Researchers report steroid-induced LASIK complication

February 18, 2009
Topical corticosteroid medications (eye drops) are routinely prescribed after LASIK surgery to prevent excess inflammation that could interfere with proper healing and vision recovery. But these same medications may cause LASIK complications in some patients, say researchers in Spain.

Tomas Moya Calleja, MD and colleagues at the Instituto Oftalmologico Europeo in Valencia, Spain, report on three cases of a LASIK complication called interface fluid syndrome (IFS) in the February 2009 issue of Journal of Refractive Surgery. In all cases, the problem was caused by steroid-induced increase in intraocular pressure (IOP) from medications used to control inflammation after surgery.

Symptoms of post-LASIK interface fluid syndrome

All three patients had similar symptoms. They all underwent successful LASIK surgery and had no prior history of glaucoma, but for different reasons used steroid eye drops for an extended period after surgery.

Approximately three weeks after steroid treatment began, all three patients experienced:

Measurements of intraocular pressure (IOP) varied, as one patient had elevated IOP in both eyes, one patient had normal IOP and one had low IOP if measured at the apex of the cornea but high IOP if measured in the corneal periphery. None of the patients experienced pain or showed signs of inflammation inside the eye (behind the cornea).

Treatment of IFS after LASIK

All patients were diagnosed as having interface fluid syndrome and were immediately treated with medication to lower their eye pressure.

Approximately one month after treatment, the symptoms disappeared and all patients recovered the uncorrected visual acuity they had achieved after LASIK.

Risk and cause of interface fluid syndrome

Though short-term use of corticosteroid eye drops after LASIK has been proven safe and effective in controlling post-operative inflammation. But it is reported that five percent to seven percent of the general population responds to corticosteroids with significant increases in intraocular pressure.

As pressure increases inside the eye in these individuals, fluid in the anterior chamber (behind the cornea) moves through the corneal endothelium (back cell layer of the cornea) into the cornea. In normal corneas, this fluid passes through the central tissue layer of the cornea (the stroma) and enters the epithelium (the outer layer), causing epithelial edema.

After LASIK, because a virtual space is created between the flap and the stromal bed of the cornea, the fluid gathers in this interface, note the researchers. It is this accumulation of fluid in the flap interface that causes the steepening of the central cornea and the regression of nearsightedness.

This fluid in the flap interface can also cause a "shock absorber" effect, according to the researchers, causing IOP measurements taken at the corneal apex to read normal or low, even though the actual pressure within the eye is elevated.

Early detection and correct diagnosis of IFS is crucial

All cases in this report were successfully managed with no loss of vision. However, early detection of interface fluid syndrome is essential to prevent optic nerve damage and permanent vision loss from prolonged elevation of IOP, say the researchers.

This means it is critical for LASIK patients to keep their appointments for follow-up exams after LASIK, even if they are experiencing no pain or vision problems.

It is also important for eye doctors who perform these post-operative exams to carefully evaluate the cornea and take IOP measurements, especially in cases of decreased vision and regression of myopia after initially good LASIK results.

It is also important for eye doctors to correctly diagnose IFS, as some of its symptoms are similar to diffuse lamellar keratitis (DLK), another LASIK complication, but one that requires a different treatment approach.