SUMMARY
Purpose:
To analyze Clinical outcome and ultrasound biomicroscopy (UBM) characteristics of excimer laser phototherapeutic keratectomy (PTK) for a variety of superficial corneal disorders.
Patients and Methods:
Prospective study of 36 eyes of 29 patients (16 males), age 10 to 76 years, with superficial corneal disorders divided in to 4 groups ( dystrophy, 10; degeneration, 20; post-infection, 5; post-trauma, 1) Patients were submitted to PTK using argon fluoride excimer laser with 193 nm wavelength. They were assessed regarding preoperative and postoperative best spectacle-corrected visual acuity, cycloplegic refraction, biomicroscopy and dilated fundus examination, corneal topography, tonometry, and when possible, high-frequency ultrasound (ultrasound biomi-croscopy -UBM) was performed. Follow-up ranged from 1 to 29 months.
Results:
The average number of laser pulses was 279, with mean predicted stromal ablation of 69. 7µm. The mean logarithmic visual acuity improved from 201162 to 20187 (p < O. OI) in 23 eyes (67.6%), 8 eyes (23.5%) remained stable and 3 eyes (8.5%) lost at least one line. Corneal transparency improved clinically in all cases ( 100%) and one patient presented recurrence of his pathology (2.8%). As compli-cations: mean hyperopic shift was +2.87D in 82.3%, delayed reepithelialization in 1 case (2.8%) and excessive corneal thinning in 1 case (2.8%). At preoperati-ve UBM examination, mean stromal change was 140 µm (total thickness of 523 µm) and postoperatively, residual stromal opacities were detected in 7 eyes.
Conclusion:
Phototherapeutic keratectomy is a safe procedure which ojfers Clinical improvement and delays penetrating or lamelar keratoplasty in some particular corneal disorders. The UBM was useful to program preoperatively the ablation required for removing the corneal opacities and postoperatively for eventual retreatment in case of residual stromal opacities.