PPIB and diabetic retinopathy: The findings indicated that higher serum concentrations of α-carotene, β-carotene, and lutein/zeaxanthin were negatively associated with the risk of cataracts; a higher serum concentration of β-cryptoxanthin was negatively associated with the risk of glaucoma; higher serum concentrations of β-carotene and β-cryptoxanthin were negatively associated with the risk of diabetic retinopathy; and a higher serum concentration of lycopene was negatively associated with the risk of AMD.