Anterior Segment Oct Evaluation of a Caucasian Population to Assess Posterior Corneal Arc Length as a Utility for Planning Endothelial Keratoplasty

Purpose: To provide the first data of posterior corneal arc length (PCAL) in a British Caucasian population. To assess the correlation of PCAL with white to white distance (WTW), anterior chamber (AC) diameter and depth. To establish whether PCAL measurements may be of use in determining graft diameter in corneal endothelial transplant surgery. Methods: Patients were recruited from a database of anterior segment optical coherence tomography images (Tomey Casia). Patients were included if their demographic information confirmed that they were White British. Patients were excluded if they had previously had corneal surgery. 192 eyes from 100 patients were used for the study. Together with Tomey, we developed image analysis software to measure PCAL. This was used to measure PCAL, WTW and AC depth and diameter. Statistical analyses were performed using SPSS 14.0. Results: 54 patients were female (54%) and 46 were male (46%). The average age of the patients was 62 (range 22-88). Mean PCAL was 13.38mm (95% CI 13.48 and 13.68) (SD 0.71mm). Mean WTW was 11.74mm (95% CI 11.67 11.82) (SD 0.51mm). PCAL correlated extremely well with WTW distance (Pearson’s r = 0.924, p<0.01). Mean WTW to PCAL ratio was 1.16 (1.08-1.21). PCAL also correlated well with ACD (Pearson’s r = 0.541, p<0.01) but the ratio of PCAL to ACD was much less consistent than that of PCAL to WTW. Conclusion: This is the first data documenting PCAL measurements in a White Caucasian population. PCAL correlates closely with WTW and may be extrapolated using a conversion factor of 1.16. PCAL may have a role in sizing of endothelial grafts but further analysis and larger patient numbers are required.