Age and Sex Variation in the Duration of Action and Corneal Touch Threshold (CTT) following Instillation of 0.5% Topical Ophthalmic Proparacaine and Tetracaine Hydrochlorides

Table 1

Minimum CTT values and total duration of effect with respect to age.

Anesthetic	Age group	Minimum CTT (cm)	Total duration (min)
Proparacaine HCL	Young	0.23 ± 0.71	25
	Middle-aged	0.14 ± 0.65	25
	Elderly	0.00 ± 0.00	20
Tetracaine HCL	Young	0.60 ± 1.23	30
	Middle-aged	0.25 ± 0.91	20
	Elderly	0.00 ± 0.00	20