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Noncontact Evaluation of Corneal Grafts: Swept-Source Fourier Domain OCT Versus High-Resolution Scheimpflug Imaging

Purpose: To study the reliability and repeatability of anterior segment measurements in patients who underwent penetrating keratoplasty with swept light source Fourier domain anterior segment optical coherence tomography (SS-OCT) in comparison with a high-resolution Scheimpflug camera. Methods: Keratometry (K) and elevation data of the anterior and posterior corneal surfaces, central corneal thickness, and anterior chamber depth were determined in 56 postkeratoplasty eyes (mean age: 59.6 ± 16.5 yrs) with SS-OCT (CASIA SS-1000; Tomey) followed by Scheimpflug photography (Pentacam High Resolution; Oculus). Examinations were also performed on 48 right eyes of 48 age-matched healthy subjects (mean age: 66.3 ± 7.0 yrs). Results: A statistically significant difference was detected between both tomographers in anterior flat K [1.7 ± 4.92 diopters (D)], posterior astigmatism (1.32 ± 5.7 D) and elevation (6.65 ± 14.07 &mgr;m), and central corneal thickness (27.39 ± 90.81 &mgr;m) and anterior chamber depth values (0.14 ± 0.66 mm) in patients who had undergone corneal transplantation (P < 0.05). In the postkeratoplasty group, repeatability of SS-OCT was higher for every anterior segment parameter in comparison with the Pentacam. In corneal grafts, the variability between 3 consecutive measurements on the same subject was remarkably lower for every parameter while using SS-OCT. Conclusions: In patients who had undergone corneal transplantation, SS-OCT provided more reliable and repeatable anterior segment evaluations when compared with the rotating Scheimpflug system. Our findings suggested that the tested high-resolution swept-source OCT system is a comprehensive and precise diagnostic tool for postoperative follow-up of patients who have undergone penetrating keratoplasty.