Table 3. Pair-wise comparison of BDNF among groups by using Tukey's test.

BDNF: brain-derived neurotrophic factor; DR: diabetic retinopathy; NPDR: non-proliferative diabetic retinopathy

Pair-wise comparison of BDNF
Groups	Groups	Mean Difference	Std. Error	P-value
Non-diabetics	Diabetics without Diabetic Retinopathy	1.16345*	.18293	0.000*
	Diabetics with Non-Proliferative Diabetic Retinopathy	1.81475*	.18293	0.000*
	Diabetics with Proliferative Diabetic Retinopathy	3.16250*	.18293	0.000*
Diabetics without DR	Diabetics with Non-Proliferative Diabetic Retinopathy	.65130*	.18293	0.004*
	Diabetics with Proliferative Diabetic Retinopathy	1.99905*	.18293	0.000*
Diabetics with NPDR	Diabetics with Proliferative Diabetic Retinopathy	1.34775*	.18293	0.000*