Table 1 Previously suggested parameters used to determine progression of ectatic disease
From: Assessing progression of keratoconus: novel tomographic determinants
Suggested Parameter | Value Representing Progression | Validated |
|---|---|---|
Spherical power, and higher order irregular astigmatism [32, 35] | Positive Rate of Change per Year | No |
Spherical component, regular astigmatism, decentration component, and higher order irregularity [37] | Positive Rate of Change per Year | No |
≥ 1.00 D increase | No | |
Kmax – Kmin [38] | ≥ 1.00 D increase | No |
Kmean (average of Kmax and Kmin) | ≥ 0.75 D increase | No |
Pachymetry [38] | ≥ 2 % decrease in central thickness | No |
Back optic zone radius of the best fitting contact lens [27] | 0.1Â mm or more decrease | No |
Increase in the central K power [25] | ≥ 1.50 D increase from baseline | No |
Manifest cylinder [38] | Increase of ≥ 1.00 D in 24 months | No |
Manifest refraction spherical equivalent change (MRSE) [27, 38] | ≥ 0.50 D | No |
ISV [22] | Specific values for each KCN stage | No |
IHA [22] | Specific values for each KCN stage | No |