Drug Administration Premarket Approval Research Articles

A Prospective Multicenter Trial of Excimer Laser Phototherapeutic Keratectomy for Corneal Vision Los

The 193-nm argon fluoride excimer laser can remove corneal scars and smooth corneal irregularities, obviating corneal transplantation. We conducted a prospective multicenter trial of excimer laser phototherapeutic keratectomy for corneal vision loss as a basis for Food and Drug Administration premarket approval. We treated 232 eyes of 211 patients with corneal vision loss. All had corneal pathology in the anterior 100 microns of the stroma. Mean postoperative follow-up was 10 +/- 8 months. The primary outcome variable was change in best spectacle-corrected visual acuity. At postoperative month 12, best spectacle-corrected visual acuity improved in 46 (45%) of 103 eyes and worsened in nine (9%) of 103 eyes by 2 or more Snellen lines. Best spectacle-corrected visual acuity improved by a mean of 1.6 +/- 2.8 Snellen lines (95% confidence interval, 1.1 to 2.1 lines). Every postoperative visit confirmed statistically significant improvement of mean best spectacle-corrected acuity. At month 12, treated eyes had a mean hyperopic shift in refraction of 0.87 diopter and a mean reduction in astigmatism of 0.36 diopter. Treatment appeared most effective in eyes with hereditary corneal dystrophies, Salzmann's nodular degeneration, and corneal scars, and least effective in eyes with calcific band keratopathy. Complications included recurrence of underlying pathology, corneal graft rejection, and bacterial keratitis. Argon fluoride excimer laser phototherapeutic keratectomy is effective, with relatively few complications, for treating vision loss from corneal opacification or irregularity. Efficacy, however, varies widely depending upon individual eyes and underlying diagnoses.