Corneal density with the Pentacam after photorefractive keratectomy

To measure corneal density and evaluate corneal haze in unoperated eyes and in eyes after photorefractive keratectomy (PRK).

Forty-nine patients (91 eyes) who underwent PRK and 48 control patients (76 unoperated eyes) were measured with the densitometry program of the Pentacam Scheimpflug imaging system (Oculus Optikgeräte GmbH) (0=no clouding, 100=tissue completely opaque). Eyes were categorized as myopic or hyperopic (myopia group and hyperopia group), with subgroups defined as unoperated (unoperated myopia group and unoperated hyperopia group), postoperative clear corneas (clear cornea myopia group and clear cornea hyperopia group), and postoperative with haze (myopia haze group and hyperopia haze group). The ANOVA option of the Statistica 8.1 program package (StatSoft Inc) was used to compare subgroups.

Maximum density of postoperative corneas with haze (myopia haze group, 46.2±16.2; hyperopia haze group, 50.2±25.8) was higher than in postoperative clear corneas (clear cornea myopia group, 29.9±8.7; clear cornea hyperopia group, 22.9±3.1), but maximum corneal density in the latter subgroups showed no difference compared with unoperated controls (unoperated myopia group, 25.1±2.4; unoperated hyperopia group, 22.8±3.2). Differences among subgroups were not found outside the 6-mm diameter ablation zone. In hazy myopic corneas, there was a strong decreasing density trend from the apex to the 3-mm radius (P<.001, R=-0.5), which continued towards the periphery at 4.5 mm (P=.019, R=-0.21). Hyperopic mild hazy corneas showed a density increase from the apex to 3 mm (P<.001, R=0.4), followed by a decrease towards the periphery (P<.01, R=-0.4).

The densitometry program of the Pentacam can provide a useful objective measure of postoperative and other mild corneal haze.