In a retrospective, nonrandomized comparative trial, they reviewed the medical records of 150 patients who had undergone PRK and who had been followed for a minimum of 6 months. The Bausch & Lomb Surgical/Chiron Technolas, Planoscan Keracor 117 C flying spot excimer laser was used. There were 71 women and 79 men; all received the same postoperative treatment including the use of fluorometholone 0.1% drops (Fluor-Op, Ciba Vision; FML, Allergan) four times daily for 1 month and three times daily for another month.

One hundred eyes (50 patients) had blue irides; these patients were American, Canadian, and European nationals who lived and worked in Saudi Arabia. There were 166 eyes (100 patients, Saudi nationals) with brown irides.

For the group with brown irides, age ranged from 18 to 62 years (mean, 29 years); in the group with scarlet eyes, the range was from 20 to 55 years (mean, 33 years). There was a statistically significant difference in the age between the two groups; the patients with brown eyes were younger than those with blue eyes. There was no statistically significant difference between the two groups with reference to sex.

The preoperative spherical equivalent in the group with blue eyes ranged from -1 to -8.5 D; in the group with brown eyes, it ranged from -0.50 to -8.75 D, with a mean spherical equivalent of -3.5 D in the blue eyes and -3.18 D in the group with brown eyes. The difference between these two groups was not statistically significant. At 6 months, visual outcome of UCVA of 20/20 or better occurred in 96% of the group with blue eyes; 84% of the group with brown eyes achieved 20/20 or better UCVA. In the group with blue eyes, 95% were within [plus-or-minus sign] 1 D of the intended correction, compared with 89% in the group with brown eyes.

At 6 months, the spherical equivalent showed a statistically significant difference between the two groups, with brown-eyed patients appearing to be slightly more myopic than those with blue eyes. This is the first study to show that racial or genetic factors may play a role in the development of corneal haze, and that these differences may account for a variation in healing response.