Abstract
Purpose :
To compare the variability on pachymetry, elevation and keratometry measurements using Scheimpflug imaging analysis between normal eyes and progressive and no progressive keratoconus (KC) eyes at 1 year of follow up.
Methods :
Prospective, cohort study that included 34 normal and 81 KC eyes that attend to Oftalmosalud Institute, Peru, between January 2015 to august 2018. Visual acuity, refraction and Scheimpflug analysis (maximum keratometry [Kmax], pachymetry at the thinnest point [TP], posterior elevation [ElevP], and D index was performed at initial evaluation and one year apart, no treatments were performed on these eyes during that time interval. KC group was divided according to progression or not, progression was defined as an increase on Kmax of 1D and increase on D index of 0.42 at 1 year. Variability was assessed using interquartile range (IQR) and Wilcoxon signed rank test for mean comparisons.
Results :
On normal eyes mean change were -0.06±0.33D, 2.32±6.58um, 0.53±2.86um, 0.15±0.38 on Kmax, TP, ElevP and D index respectively at 1 year of follow up. Non-progressive KC mean change were -0.02±0.49D, -1.75±14.61um, -0.36±7.14um and 0.15±0.52 in Kmax, TP, ElevP and D index. Progressive KC mean change were -2.26±0.76D, -8.73 ± 20.55um, 2.18±4.58um and 0.14 ± 0.49 in Kmax, TP, ElevP, and D index. IQR for pachymetry was 8.00, 18 and 28 in normal, non-progressive and progressive KC. There were no significant differences in the variability of these values at 1 year of follow up between the 3 groups in pachymetry (p= 0.21) and posterior elevation (p = 0.60).
Conclusions :
Both progressive and non-progressive keratoconus had big variability on pachymetry and elevation measurements at 1 year of follow up, which makes difficult to assess progression. Also, normal eyes experienced variability on measurements, but with less magnitude than progressive and no progressive KC.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.