Comparison of central corneal thickness by ultrasound pachymetry, optical coherence tomography and specular microscopy

Abstract

The purpose of this study was to compare and correlate the central corneal thickness (CCT) measurement obtained by ultrasound pachymetry, optical coherence tomography (OCT) pachymetry, and specular microscopy to better understand the importance of central corneal thickness in the evaluation and diagnosis of glaucoma. The study compared the central corneal thickness of 8 patients (16 eyes) with each modality. The mean CCT was 531.47 ± 42.20 µm by ultrasound pachymetry. In comparison, CCT averaged 517.63 ± 43.29 µm by OCT, and 529.88 ± 57.02 µm by specular microscopy. Correlations (r 2) of CCT were analyzed, whereby the three modalities were compared to one another. For ultrasound pachymetry vs. OCT pachymetry, r 2 =0.93 and P<0.0001. For ultrasound pachymetry vs. specular microscopy, r 2 =0.88 and P<0.0001. For OCT pachymetry vs. specular microscopy, r 2 =0.98 and P<0.0001. In conclusion, OCT pachymetry, specular microscopy, and ultrasound pachymetry can be used in clinical settings to measure CCT. Our study showed statistically significant linear correlations among the three modalities of measurement. Accurate measurement of CCT aid ophthalmologists in managing glaucoma. The ultrasound pachymeter showed the least variance among the techniques and therefore, may be the most accurate method of measuring central corneal thickness.