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. Author manuscript; available in PMC: 2018 Nov 15.
Published in final edited form as: Prog Retin Eye Res. 2018 Jul 13;67:150–167. doi: 10.1016/j.preteyeres.2018.05.002

Table 1.

The Amsler-Krumeich classification system.

STAGE Mean keratometry reading Thickness Spectacle refraction Slit lamp
1 Mean central K readings < 48 D Myopia, induced astigmatism, or both < 5.00 D Eccentric steepening
2 Mean central K readings < 53.00 D Corneal thickness > 400 micron Myopia, induced astigmatism, or both from 5.00–8.00 D Absence of scarring
3 Mean central K readings > 53.00 D Corneal thickness 300–400 micron Myopia, induced astigmatism, or both from 8.00–10.00 D Absence of scarring
4 Mean central K readings > 55.00 D Corneal thickness < 200 micron Refraction not measurable Central corneal scarring