Abstract:
To determine the reproducibility of total and epithelial corneal thickness of the central, mid–peripheral and peripheral cornea measurements obtained using the Sonogage Corneo–Gage Plus 2 ultrasound pachymeter. Twenty–seven subjects were examined at the New England College of Optometry and 20 subjects were examined at the Southern College of Optometry using the same protocol. Five measurements were obtained for the right eyes only at each of five corneal locations: central and at two points on each side on the horizontal meridian (mid–peripheral and peripheral measurements of the nasal and temporal cornea). A chin rest was used to maintain head position and a fixation target with five fixation points was used to maintain fixation. A constant testing distance of 11mm was used such that the targets corresponded to corneal points approximately 3mm and 5.5mm temporal and nasal. Subjects were scheduled for a second visit one week later at approximately the same time of day of their first visit. The same testing procedures were performed at the second visit. Paired t–tests were used to compare within subject measurements.
The only significant differences between visits were for the full corneal thickness measurements at both the nasal and temporal mid–peripheral locations. The mean differences for these locations were 12 and 13 microns, respectively. Epithelial corneal thickness and central and peripheral total corneal thickness measurements using the Corneo–Gage Plus 2 pachymeter were reproducible; however, midperipheral total corneal thickness measurements were statistically different.
Keywords: cornea: basic science • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)