Purpose
To demonstrate the applicability of speckle-free spectral optical coherence tomography (SOCT) for assessment of the corneal surface changes after excimer laser photorefractive keratectomy (PRK). To indicate differences in the healing process between conventional PRK and transepithelial PRK using OCT technology.
Methods
A total number of 8 eyes with myopia or myopic compound astigmatism after laser refractive correction were imaged and tracked in time by novel speckle-free OCT prototype device. Two kinds of interventional procedure were applied using Amaris 750 S (Schwind eye-tech-solutions): conventional PRK with epithelium removed with alcohol (PRK group) and transepithelial PRK (TransPRK group). SOCT measurements were performed before the surgery, once a day during the first postoperative week, once a week in the next month, as well as 2 and 3 months after the surgery. Novel technique of reduction of the speckle contrast by averaging of 16 A-scans deflected orthogonally was implemented.
Results
High quality, high-resolution OCT images with reduced speckle contrast of the central cornea and peripheral cornea with limbus were acquired before the surgery and in first postoperative days after PRK and TransPRK. This technique enabled to visualize the basal epithelial cells layer for the first time with OCT. The mean time to cover the stoma with epithelium was 2.4 days ± 0.8 (SD) in TransPRK group and 3.6 ± 0.9 days in PRK group (P<0.05). In both groups the increased thickness and reflectivity of new epithelium was observed. Central thickness of the epithelium returned to preoperative values after 20 ± 5 days and 24 ± 6 days respectively (P>0.05).
Conclusions
Introduction of the novel speckle contrast reduction in OCT technique has potential of improving the diagnostic capabilities of this method when applied for corneal imaging. It provides new information of clinical value regarding the healing process after laser photorefractive keratectomy in a non-invasive way.
Keywords: 482 cornea: epithelium •
686 refractive surgery: PRK