. Author manuscript; available in PMC: 2015 Feb 1.

Published in final edited form as: Ophthalmology. 2013 Nov 26;121(2):459–468. doi: 10.1016/j.ophtha.2013.09.013

Table 2.

Definition and comparison of Ocular Response Analyzer variables (mean ± SD) based on Applanation Signal Intensity for normal and keratoconus groups.

Group	Variable	Operational Definition	Related to:	Normal	Keratoconus	P value
1: Applanation Signal Intensity	A1	Peak intensity of 1^st applanation event	Maximum surface area achieving planarity during inward deformation	681 ± 153	433 ± 148	<0.0001
	A2	Peak intensity of2^nd applanation event	Maximum surface area achieving planarity during recovery	564 ± 172	371 ± 169	<0.0001
	ApplanationPeakDiff	A2 – A1	Difference in maximum planarity between inward and recovery phases	−117 ± 197	−62 ± 148	0.02
	ConcavityMin	Minimum applanation intensity between A1 and A2	Depth and irregularity (non-planarity) of deformation	61 ± 11	39 ± 8	<0.0001
	ConcavityMean	Mean applanation intensity between A1 and A2	Depth and irregularity of deformation, averaged	150 ± 28	93 ± 26	<0.0001

SD = standard deviation