PURPOSE: To assess the correlation between optical coherence tomography (OCT) and ultrasound pachymetry (USP) as methods for analysing central corneal thickness (CCT) and to evaluate ophthalmic factors affecting CCT. METHODS: The eyes of 3070 subjects of the Northern Finland Birth Cohort (NFBC) were examined at the age of 45-49 years. CCT was measured using OCT and USP. The optic nerve head (ONH) and retinal nerve fibre layer (RNFL) parameters were assessed with OCT and Heidelberg Retina Tomograph (HRT). Visual acuity and refraction were evaluated with an autorefractometer and intraocular pressure (IOP) with rebound tonometry (iCare) and Goldmann applanation tonometry (GAT). The evaluation of glaucomatous damage was based on the ONH, RNFL and visual fields. RESULTS: The mean CCT was 540.0 ± 34.8 μm with OCT and 540.7 ± 39.6 μm with USP. There was a strong correlation (r = 0.927, p < 0.001) between the devices, and the inter-method agreement increased with better visual acuity (r = 0.086, p = 0.003). The CCT measured with OCT correlated with IOP (r = 0.400 (iCare), r = 0.314 (GAT), p < 0.001), rim area (r = 0.048, p = 0.011), cup volume (r = -0.046, p = 0.014) and RNFL (r = 0.041, p = 0.027). We found no correlation between CCT and glaucoma. CONCLUSION: The results indicate that OCT and USP may be used interchangeably when measuring CCT. As expected, CCT had a substantial correlation with IOP, but was also positively associated with ocular neural tissue (rim and RNFL) and negatively with the optic cup.
Qvist et al. (Wed,) studied this question.