["Central islands"--an early postoperative complication after photorefractive keratectomy]

After myopic photorefractive keratectomy undercorrected zones in the center of the treated cornea (central islands (CI)) occur early postoperatively occasionally the reason for double-vision, halos and reduction of best corrected visual acuity.

Sixty-two eyes of 33 patients were treated with an 193 nm excimer laser for correction of myopia (range: -1.0 to -12.0 D) and an optical zone of 6.0 mm. The patients were selected consecutively regarding the follow-up examination which ranged from 1 month to 21 months after surgery.

At 1 month after surgery the incidence of central islands was 72.6%. It rarely occurs after corrections of -3.0 D and less but may be detected in every case of correction of -6.0 D and more. The correlation between attempted correction and incidence of central islands is statistically significant (p < 0.005). Approximately 21% of the patients were steroid responders whose central islands appeared more marked.

Central islands are an early postoperative complication with a not yet decided cause. Depending on attempted correction (D) and the follow-up the central islands disappear and/or did not result in reduction of visual acuity. In contrast, in patients with increased corticosteroid response the central islands persisted longer (15 months and more). Reoperations because of central islands should not be performed before 6 months after surgery. We describe a new form of central corneal iron deposit.