[Phototherapeutic keratectomy (o-PTK) with 193 nm excimer laser for superficial corneal scars. Prospective long-term results of 31 consecutive operations].

PURPOSE: To investigate the functional and morphological long-term outcome of phototherapeutic keratectomy (PTK) for superficial corneal scars of varying origin.

PATIENTS AND

METHODS

Between 1989 and 11/2002, 317 PTKs were performed in Erlangen, of which 31 consecutive procedures were assessed in this prospective study. The intended laser ablation depth after epithelial debridement and pannectomy varied from 12 to 150 microm. We used the slit-scanning-mode (Carl Zeiss Meditec AG) with a repetition rate of 20/s or 25/s, a pulse energy of 14.5 mJ (median) and a pulse rate of 2565+/-2036 (222-6962). In most cases a 6.0 mm metal mask was used to protect peripheral Bowman's layer.

RESULTS

After a mean follow-up of 2.0+/-1.9 (maximum 6.9) years, best-corrected visual acuity increased from preoperatively 0.3+/-0.2 to 0.5+/-0.3 (increase 87%, no change 10%, decrease 3%). Corneal surface topography regularized significantly (p=0.02). The spherical equivalent increased only slightly from -0.4+/-2.5 D preoperatively to 0.2+/-2.9 D postoperatively. Likewise, mean keratometric central power did not change significantly. In 10 eyes the maximum postoperative haze was mild, in 4 eyes moderate, and there was only one recurrent scar after delayed epithelial healing following epidemic keratoconjunctivitis.

CONCLUSIONS

In superficial corneal scars of varying origin an o-PTK using the 193 nm excimer laser can moderately increase visual acuity in most cases. Therefore, a lamellar or penetrating keratoplasty might be avoided.