Role of Noncontact Pachymetry Systems in Measurement of Central Corneal Thickness
Purpose
To compare reliability and correlation of non-contact pachymetry systems: Anterior segment OCT (ASOCT) and Orbscan with the standard contact ultrasound pachymetry in measuring central corneal thickness (CCT).
Methods
This was a prospective comparative observational study of two hundred eyes of 100 patients who presented to a tertiary eye care center in South India over a 6 month period. Central corneal thickness measurements were done using Orbscan, Visante ASOCT and ultrasound pachymetry. The results of three measurements of each machine were averaged and data was analyzed using analysis Oo variance (ANOVA) test, correlation coefficient, Bland and Altman plot and linear regression.
Results
The mean central corneal thickness of males was found to be significantly greater than that of females mean CCT for Ultrasound pachymetry, AS OCT and Orbscan were 530.41, 517.19 and 532.3µm respectively. USG pachymetry measurement was found to be highly correlated with that measured by AS OCT (r = 0.95, P < 0.001) and Orbscan (r = 0.89, P <0.001).
Conclusion
Orbscan showed best reproducibility with ultrasound pachymetry in measuring CCT and can be a good alternative tool in measuring CCT. The ASOCT could serve as a powerful non-contact tool to asses both corneal thickness and pathology with accuracy.