Table 2.

Pain outcomes: proparacaine versus tetracaine, graded 0 to 10

Time point	Proparacaine pain adjusted mean ± SE	Tetracaine pain adjusted mean ± SE	Adjusted mean difference (P-T)* (95% CI)	P-value
Total sample (n=128 patients)
Instillation	1.1±0.2	3.2±0.2	−2.1 (−2.5, −1.8)	<0.001
During surgery	1.2±0.2	1.6±0.2	−0.4 (−0.8, 0.0)	0.067
Immediately postoperatively	0.9±0.1	0.9±0.1	0.1 (−0.2, 0.3)	0.60
30 minutes postoperatively	2.2±0.1	1.3±0.1	0.8 (0.5, 1.2)	<0.001
Overnight	1.3±0.2	1.6±0.2	−0.3 (−0.6, 0.2)	0.23
Postoperative day 1	1.0±0.2	1.0±0.2	0.0 (−0.2, 0.3)	0.89
LASIK (n=67 patients)
Instillation	1.0±0.2	3.1±0.2	−2.1 (−2.5, −1.6)	<0.001
During surgery	1.2±0.2	1.6±0.2	−0.4 (−1.1, 0.2)	0.22
Immediately postoperatively	1.1±0.1	1.0±0.1	0.1 (−0.2, 0.5)	0.48
30 minutes postoperatively	2.9±0.2	1.4±0.2	1.5 (1.0, 2.0)	<0.001
Overnight	0.9±0.3	1.3±0.2	−0.4 (−1.1, 0.2)	0.15
Postoperative day 1	0.4±0.1	0.3±0.1	0.1 (−0.2, 0.3)	0.53
PRK (n=61 patients)
Instillation	1.2±0.2	3.3±0.2	−2.2 (−2.7, −1.6)	<0.001
During surgery	1.2±0.2	1.6±0.2	−0.4 (−1.1, 0.2)	0.12
Immediately postoperatively	0.7±0.1	0.8±0.1	0.0 (−0.3, 0.2)	0.92
30 minutes postoperatively	1.4±0.2	1.3±0.2	0.1 (−0.2, 0.5)	0.53
Overnight	1.7±0.3	1.9±0.3	−0.2 (−0.7, 0.4)	0.52
Postoperative day 1	1.7±0.3	1.8±0.3	0.0 (−0.5, 0.5)	0.90

Notes:

^*Adjusted for pain at previous measurement time using a multivariable mixed effects linear regression model; after instillation, also adjusted for surgical procedure (LASIK or PRK).

Abbreviations: LASIK, laser in situ keratomileusis; PRK, photorefractive keratectomy; P, proparacaine; T, tetracaine; SE, standard error of the mean; CI, confidence interval.