Table 2.

Comparison of intraocular pressure and Singapore I Vessel Assessment (SIVA) measures of retinal blood vessels between the sitting position and supine position

Variable	Healthy control (n = 58)			Participants with DM (n = 50)
	Sitting	Supine	P value*	Sitting	Supine	P value*
	Mean ± SE	Mean ± SE		Mean ± SE	Mean ± SE
Intraocular pressure (mmHg)	15.1 ± 0.3	16.8 ± 0.4	<0.001	15.8 ± 0.37	17.8 ± 0.37	<0.001
Retinal arteriolar caliber (µm)	92.48 ± 3.48	89.32 ± 3.00	0.049	111.55 ± 5.93	114.69 ± 6.17	0.104
Retinal venular caliber (µm)	130.19 ± 4.89	124.89 ± 4.40	0.027	160.84 ± 6.594	161.89 ± 8.28	0.880
Retinal arteriolar fractal dimension	1.199 ± 0.006	1.196 ± 0.006	0.107	1.169 ± 0.006	1.166 ± 0.007	0.169
Retinal venular fractal dimension	1.199 ± 0.006	1.193 ± 0.005	0.003	1.179 ± 0.006	1.173 ± 0.007	0.013
Retinal arteriolar simple tortuosity	1.081 ± 0.001	1.080 ± 0.001	0.162	1.081 ± 0.002	1.085 ± 0.002	0.051
Retinal venular simple tortuosity	1.091 ± 0.002	1.089 ± 0.002	0.371	1.090 ± 0.002	1.090 ± 0.002	0.773
Retinal arteriolar curvature tortuosity (×104)	2.611 ± 0.132	2.720 ± 0.134	0.224	2.112 ± 0.198	2.005 ± 0.195	0.238
Retinal venular curvature tortuosity (×104)	3.125 ± 0.163	3.181 ± 0.155	0.574	2.581 ± 0.261	2.432 ± 0.237	0.147
Arteriolar branching angle (degrees)	68.17 ± 1.38	68.68 ± 2.33	0.810	69.71 ± 2.90	68.61 ± 2.11	0.720
Venular branching angle (degrees)	72.58 ± 2.14	70.76 ± 2.34	0.310	72.73 ± 1.43	72.01 ± 1.77	0.828

DM = diabetes mellitus; SE = standard error

* Represents paired t-test. P values in bold indicate statistical significance