Simultaneous Transepithelial Topography-Guided Photorefractive Keratectomy and Accelerated Cross-Linking in Keratoconus: 2-Year Follow-Up

Table 1

Amsler-Krumeich clinical classification of keratoconus by stage.

Stage	Characteristics
I	Eccentric steepening
	Induced myopia and/or astigmatism of ≤5.00 D
	Keratometric reading ≤48.00
	Vogt’s lines, typical topography
II	Induced myopia and/or astigmatism 5.00 to ≤8.00 D
	Keratometric reading ≤53.00
	Pachymetry ≥ 400 μm
III	Induced myopia and/or astigmatism 8.00 to ≤10.00 D
	Keratometric reading >53.00
	Pachymetry 200 to 400 μm
IV	Refraction not measurable
	Keratometric reading >55.00 D
	Central scars
	Pachymetry ≤ 200 μm

The patient is at the specific stage if one of the characteristics applies. Pachymetry is measured at the thinnest site of the cornea.
D, diopters.