Table 2. Sensation thresholds to selective stimulation of the cornea.

Stimulation	Control	Keratoconus	P
Mechanical (ml/min)	109.1 ± 24.0	139.2 ± 25.8	<0.001
Chemical (%CO 2 )	35.2 ± 1.9	39.4 ± 3.9	<0.001
Heat (Δ°C)	0.54 ± 0.26	0.91 ± 0.32	<0.001
Cold (Δ°C)	0.98 ± 0.25	1.28 ± 0.27	0.001

Data are mean ± SD values in the control (n = 20) and in the keratoconus groups (n = 19). Note: P: Mann–Whitney U test.