Effect of the Administration of Alpha-Lipoic Acid on Contrast Sensitivity in Patients with Type 1 and Type 2 Diabetes

Table 4

Characteristics of contrast sensitivity examinations in the control group with and without ALA supplementation at baseline and after 3 months.

Spatial frequencies	Control group without; ALA supplementation; CS × LC = 44 measurements			Control group with; ALA supplementation; CS × LC = 108 measurements
	Baseline	After 3 months	𝑃 value	Baseline	After 3 months	𝑃 value
A-1.5 cpd
Mean. ± SD	6.9±1.6	6.7±1.3		6.7±1.6	6.8±1.2
Range	4.0–9.0	5.0–9.0	𝑃=0.318	0.0–9.0	5.0–9.0	𝑃=0.465
Median	7.0	7.0		7.0	7.0
95% CI	[6.4; 7.4]	[6.3; 7.1]		[6.4; 7.0]	[6.6; 7.1]
B-3 cpd
Mean. ± SD	6.8±1.6	6.7±1.6		6.1±1.5	6.4±1.2
Range	3.0–9.0	3.0–9.0	𝑃=0.423	0.0–9.0	3.0–9.0	𝑃=0.027^∗
Median	6.5	7.0		6.0	7.0
95% CI	[6.3; 7.3]	[6.2; 7.2]		[5.8; 6.4]	[6.2; 6.7]
C-6 cpd
Mean. ± SD	5.9±1.8	6.0±1.5		5.4±1.9	5.5±1.7
Range	1.0–9.0	2.0–8.0	𝑃=0.414	0.0–8.0	0.0–8.0	𝑃=0.399
Median	6.0	6.0		5.0	6.0
95% CI	[5.3; 6.4]	[5.5; 6.4]		[5.1; 5.8]	[5.2; 5.8]
D-12 cpd
Mean. ± SD	4.4±2.3	4.5±2.2		4.3±1.9	4.2±1.9
Range	0.0–9.0	0.0–9.0	𝑃=0.648	0.0–8.0	0.0–8.0	𝑃=0.446
Median	4.0	4.5		4.0	4.0
95% CI	[3.7; 5.1]	[3.8; 5.2]		[3.9; 4.7]	[3.8; 4.5]
E-18 cpd
Mean. ± SD	2.9±2.6	2.5±2.4		2.9±2.2	2.6±1.9
Range	0.0–9.0	0.0–8.0	𝑃=0.127	0.0–9.0	0.0–7.0	𝑃=0.234
Median	3.0	2.0		3.0	2.0
95% CI	[2.1; 3.7]	[1.8; 3.3]		[2.5; 3.3]	[2.3; 3.0]

CS × LC: the number of contrast sensitivity measurements of each eye in 4 luminance conditions and under 5 spatial frequencies.
Spatial frequencies: A-1.5, B-3, C-6, D-12, and E-18 cpd.
*Statistically significant differences between the baseline examination of control group with ALA supplementation versus after 3 months.