PRKCB and diabetic retinopathy: 1367 Aiello LPThe effect of ruboxistaurin on visual loss in patients with moderately severe to very severe nonproliferative diabetic retinopathy initial - Results of the protein kinase C beta inhibitor diabetic retinopathy study (PKC-DRS) multicenter randomized clinical trialDIABETES. 2005 JUL; 54 (7): 2188-2197