Real-time pachymetry during photorefractive keratectomy using optical low-coherence reflectometry.
Optical low-coherence reflectometry (OLCR) was used as a noncontact method to measure the central corneal thickness of three patients intraoperatively during photorefractive keratectomy. Continuous on-line measurements were performed on the intact cornea immediately before the beginning of surgery, after the removal of the corneal epithelium, during laser tissue photoablation, and for 3 min after the ablation process. Corneal thinning due to evaporation was studied on a separate patient with the OLCR instrument, and it was found to be -0.14 microm/s during the first 5 min after epithelium removal. This baseline corneal thinning rate was used as a fit parameter to calculate actual from measured ablation depths. The measurements showed a maximum difference of +/-10 microm between planned ablations (34-92 microm) and measured ablation depths.
Böhnke
M
M
University of Berne, Inselspital, Department of Ophthalmology, Berne, Switzerland.
Widmer
S
S
Wälti
R
R
D000328:Adult; D003199:Computer Systems; D003315:Cornea / Q000473:pathology*; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D054018:Lasers, Excimer; D008875:Middle Aged; D009216:Myopia / Q000473:pathology* / Q000601:surgery; D018903:Photorefractive Keratectomy / Q000379:methods*