Phototherapeutic keratectomy for Schnyder's crystalline corneal dystrophy

Purpose. To describe the treatment of Schnyder's crystalline dystrophy (SCD) with excimer laser phototherapeutic keratectomy (PTK). Methods. Chart review of three patients (four eyes) with SCD treated with PTK between March 1992 and December 1998. Pre- and posttreatment visual acuity, subjective glare, photophobia, manifest refraction, ultrasound pachymetry, hyperopic shift, and biomicroscopic findings were studied. Brightness acuity testing (BAT) was evaluated in two eyes. Results. Four eyes were treated during the study period. The average best corrected visual acuity (BCVA) improved from 20/175 to 20/40 under bright conditions. All patients reported subjective improvement in glare and photophobia. No visually significant recurrence was observed during the follow-up period which ranged from seven months to three years. The mean spherical equivalent refractive shift was +3.28 diopter (D). One patient developed irregular astigmatism from an eccentric ablation. No vision threatening complications were observed. Conclusion. PTK can be effective at improving visual symptoms in patients with SCD. It can be a useful therapeutic alternative to lamellar or penetrating keratoplasty in these patients.