Precision Of A Posterior Segment Oct To Measure The Corneal Full Thickness And Epithelial Thickness With An Anterior Segment Adapter

To assess the precision of a posterior segment optical coherence tomography (OCT) to measure the corneal full thickness and epithelial thickness with an anterior segment adapter.

Division of eye and Vision, Department of clinical neuroscience, Karolinska Institutet, Stockholm, Sweden.

The Canon OCT HS-100 was used to map the corneal full thickness and epithelial thickness using the anterior segment adapter. The anterior segment measurements were repeated three times on each subject under repeatability conditions. All subjects included had no corneal pathologies or previous corneal surgeries. The corneal thicknesses were obtained in 17 sectors from three concentric circles (central, paracentral, and peripheral). The repeatability of corneal and epithelial thickness measurements was analysed in terms of within subject standard deviation (Sw).

77 participants were included in this study (age: 29.9± 10.2 years, spherical equivalent: -1.22 ± 2.87 D). For the corneal and epithelial thickness measurements, the Sw values in the central sector were lower than 3 and 1 microns, respectively. For the paracentral and peripheral sectors, the Sw values were not homogeneous for the corneal thickness. The Sw values for corneal thickness among the different sectors varied between 3 to 7 microns and 5 to 10 microns for the paracentral and peripheral sectors respectively.  The highest and lowest Sw values were observed for the superior and temporal sectors, respectively. For the epithelial thickness, the Sw values were lower than 2 microns in all the sectors.

The results of this study show that the posterior segment OCT with an anterior segment adapter has good precision to measure the full corneal and epithelial thickness in healthy eyes. The variation of the repeated measurements was within 2 % of the actual thickness measured.