Table 1.

Effect of Oral Sildenafil on IOP of Normal Sheep Measured with Applanation Tonometry

	Sheep No.												Mean IOP	n	SEM
	054		055		056		057		371		371
	OD	OS	OD	OS	OD	OS	OD	OS	OD	OS	OD	OS
Sex	F		M		F		F		F		M
Low-dose experiment
Baseline IOP (0 h)	9.4	9.4	11.6	11.6	11.6	11.6	13.7	14.8	9.4	9.4	10.5	9.4	11.0	12	0.5
IOP (1 h)	13.7	12.7	21.3	18.1	18.1	20.2	20.2	20.2	18.1	15.9	22.4	18.1	18.3*	12	0.9
High-dose experiment
Baseline IOP (0 h)	10.5	9.4	11.6	10.5	11.6	9.4	11.6	10.5					10.6	8	0.3
IOP (1 h)	17.0	17.0	17.0	15.9	18.1	20.2	18.1	15.9					17.4*	8	0.5

Oral sildenafil (50 mg) was administered to six sheep within 1 minute of the recording of baseline IOP, and IOP was remeasured 1 hour after drug ingestion. The experiment was repeated 2 days later at a higher dose (100 mg) in four of the six sheep. Recorded values with applanation tonometer were converted to mm Hg according to a calibration curve for sheep eyes (Gerometta et al.¹²). IOP returned to baseline values within 4 hours of sildenafil ingestion.

^*Significantly higher than respective baseline value as paired data, P < 2 × 10⁻⁵.