A recent study found that wearing orthokeratology (OK) lenses for at least a year decreases the degree of myopia, flattens the cornea and increases corneal irregularity—but not without some downfalls. While the lens does not affect basic tear secretion, the study found that it does decrease tear stability.

Researchers explored the effect overnight OK lens wear has on corneal shape and tear film stability over a one-year period. The team studied 80 patients with myopia between the ages of 11 and 18 who had worn OK lenses continuously for more than a year. The study tested patients at periods of one week and one, three, six and 12 months of wear.

The study found that the corneal shape was stable one week after patients began wearing the lens, and the corneal curvature and degree of myopia did not change significantly after that point. Corneal epithelial staining increased after lens wear, as most patients had grade I staining. However, this effect on the corneal epithelium was small and reversible.

Researchers noted that the changes to tear stability mainly occur during the first week of wear and later stabilize within a week. They suggested that regular follow-up tests of tear function may help reduce the incidence of complications.