Early corneal topography patterns after excimer laser photorefractive keratectomy for myopia

We defined early patterns of corneal topography following excimer laser photorefractive keratectomy (PRK) with a Summit Apex laser without pretreatment software, investigated changes in patterns over time, and identified factors associated with different topography patterns.

Fifty-eight eyes of 39 myopic patients were studied. EyeSys videokeratography data were analyzed at 1 week and 1, 2, and 3 months after surgery and were classified using a standardized classification system.

At 1 week, 4.3% (n = 2) of corneas showed a homogeneous topography, 0.0% showed a toric-with-axis configuration, 2.2% (n = 1) showed a toric-against-axis configuration, 8.7% (n = 4) showed an irregularly irregular topography, 17.4% (n = 8) showed a keyhole pattern, 23.9% (n = 11) showed a semicircular pattern, 41.3% (n = 19) showed a central island pattern, and 2.2% (n = 1) showed focal topographic variants. From 1 week to 1 month, 78.9% of maps changed; from 1 to 2 months, 33.3% of maps changed; and from 2 to 3 months, 40.0% of maps changed, generally to more regular patterns. The central island pattern, which predominated at 1 week, was not seen at 3 months; most had changed to the keyhole or semicircular pattern. An association was found between the central island pattern and irregularity of reflected rings on the video-image of the cornea (P = .05).

The central island pattern is an early and usually transient topography pattern following PRK. Keyhole and semicircular patterns taken together were the most prevalent in the early postoperative period. In some cases, central islands may be a consequence of corneal epithelial irregularity, and the meridional orientation of the keyhole and semicircular patterns suggests an influence of epithelial healing over time.