Purpose
To investigate corneal topographic differences between keratoconic and control eyes and the long-term changes of corneal topographic parameters in untreated keratoconic eyes, as assessed with the Pentacam.
Methods
In this retrospective case-control study, we first performed an systematic review to find eligible topographic parameters and indices for keratoconus progression. The eligible parameters and indices were compared in untreated keratoconic eyes and control eyes. Next, the discriminative ability of the tested variables was analyzed. Furthermore, the difference between baseline and follow-up was assessed. All patients underwent at least one Pentacam scan.
Results
A total of 310 untreated eyes with follow-up data were identified and compared with 361 control eyes. Most topographic parameters and indices differed significantly between both groups (p<0.001). Receiver operating curve analysis revealed the highest area under curve values for Kmax, Rmin, ISV, IVA, KI and IHD (0.876, 0.871, 0.870, 0.874, 0.885, 0.884 and 0.887, respectively). Parameters that significantly changed over a mean follow-up of 24.17 months were Kmax, Rmin, K2 B, Kmean B, Rm B, Rh B, chamber volume, ACD and corneal volume.
Conclusions
Our data indicates that the maximum keratometry and the steepest radius of front and back corneal surface are the most eligible parameters to follow keratoconus progression on long-term. Index of surface variance (ISV) and index of height decentration (IHD) may be the most sensitive for diagnosis. Also standard notations of parameters should be considered in future research.