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Title

Is keratoconus a real ectasia: analysis of corneal surface area in normal eyes and keratoconus ?

Purpose	To compare anterior and posterior corneal surface areas in normal cornea and keratoconus. To correlate corneal surface area to corneal biometric values (white to white, maximal keratometry)
Methods	We retrospectively analyzed 12 587 elevation maps from 8162 eyes and 7003 maps from 2041 keratoconus. Elevation maps were acquired by Orbscan II. Corneal surface areas were calculated using digital elevation model and extrapolation to real corneal diameter.
Results	Anterior and posterior surface areas and corneal diameter are larger in keratoconus. Surface areas are directly correlated to corneal diameter. Maximal keratometry is inversely proportional to corneal diameter. In normal eyes, anterior and posterior surface areas are inversely correlated to maximal keratometry. In keratoconus, corneal surface areas don’t increase with maximal keratometry.
Conclusion	Keratoconus should not be considered as a real ectasia but greater as an isometric deformation with a central steepening and a peripheral flattening.
Conflict of interest	No

Authors 1

Last name	CRAHAY
Initials	F-X
Department	CHR Citadelle
City	Liège

Authors 2

Last name	Debellemaniere
Initials	G
Department	Fondation Ophtalmologique Adolphe de Rothschild
City	Paris

Authors 3

Last name	Ghazal
Initials	W
Department	Fondation Ophtalmologique Adolphe de Rothschild
City	Paris

Authors 4

Last name	Tobalem
Initials	S
Department	Fondation Ophtalmologique Adolphe de Rothschild
City	Paris

Authors 5

Last name	Morant
Initials	S
Department	Fondation Ophtalmologique Adolphe de Rothschild
City	Paris

Authors 6

Last name	Rampat
Initials	R
Department	Fondation Ophtalmologique Adolphe de Rothschild
City	paris

Authors 7

Last name	Gatinel
Initials	D
Department	Fondation Ophtalmologique Adolphe de Rothschild
City	Paris