Editing Keratoconus (section)

=== Stages ===
[[File:Corneal topography, stage II keratoconus (Elise A. Slim et al.).svg|thumb|Corneal topography showing stage II keratoconus]]
Once keratoconus has been diagnosed, its degree may be classified by several metrics:<ref name="Gupta">{{cite web | author=Gupta D| title=Keratoconus: A clinical update| url=http://www.optometry.co.uk/files/882ed4bcea848897cbbe928e8bd1b0c3_gupta20050715.pdf | access-date=26 March 2006|archive-url = https://web.archive.org/web/20060515104049/http://www.optometry.co.uk/files/882ed4bcea848897cbbe928e8bd1b0c3_gupta20050715.pdf |archive-date = 15 May 2006|url-status=dead}}</ref>
* The steepness of greatest curvature from 'mild' (< 45 [[dioptre|D]]), 'advanced' (up to 52 [[dioptre|D]]) or 'severe' (> 52 [[dioptre|D]]);
* The morphology of the cone: 'nipple' (small: 5&nbsp;mm and near-central), 'oval' (larger, below-center and often sagging), or 'globus' (more than 75% of cornea affected);
* The corneal thickness from mild (> 506 μm) to advanced (< 446 μm).

Increasing use of corneal topography has led to a decline in use of these terms.<ref name="Gupta"/>

{| class="wikitable"
|-
!Stage
!Characteristics<ref>{{cite journal | vauthors = Krumeich JH, Kezirian GM| date = April 2009 | title = Circular keratotomy to reduce astigmatism and improve vision in stage I and II keratoconus | pmid = 19431926 | journal = J. Refract. Surg. | volume = 25 | issue = 4| pages = 357–65 | doi=10.3928/1081597x-20090401-07}}</ref><ref>{{cite journal | vauthors = Krumeich JH, Daniel J| date = August 1997 | title =Lebend-Epikeratophakie und Tiefe Lamelläre Keratoplastik zur Stadiengerechten chirurgischen Behandlung des Keratokonus (KK) I-III|language=de |trans-title=Live epikeratophakia and deep lamellar keratoplasty for I-III stage-specific surgical treatment of keratoconus| pmid=9379645 | journal = Klin. Monbl. Augenheilkd. | volume = 211 | issue = 2| pages = 94–100 | doi=10.1055/s-2008-1035103| s2cid = 72600086 }}</ref>
|-
|Stage 1
|
* Eccentric steepening Induced myopia and/or astigmatism of ≤ 5.0 D
* K-reading ≤ 48.00 D
* Vogt's lines,<ref>[http://webeye.ophth.uiowa.edu/eyeforum/atlas/pages/vogts-striae.htm Vogt's striae in keratoconus, University of Iowa Health Care, Ophthalmology and Visual Sciences] {{webarchive|url=https://web.archive.org/web/20160813124346/http://webeye.ophth.uiowa.edu/eyeforum/atlas/pages/vogts-striae.htm |date=13 August 2016 }}</ref> typical topography
|-
|Stage 2
|
* Induced myopia and/or astigmatism between 5.00 and 8.00 D
* K-reading ≤ 53.00 D
* Pachymetry ≥ 400&nbsp;μm
|-
|Stage 3
|
* Induced myopia and/or astigmatism between 8.01 and 10.00 D
* K-reading > 53.00 D
* Pachymetry 200 to 400&nbsp;μm
|-
|Stage 4
|
* Refraction not measurable
* K-reading > 55.00 D
* Central scars
* Pachymetry  ≤ 200&nbsp;μm
|-
| colspan="2" | Stage is determined if one of the characteristics applies.<br>
Corneal thickness is the thinnest measured spot of the cornea.
|}