Percentage of participants receiving annual diabetic retinopathy screening examinations , percentage of eyes with worsening diabetic retinopathy during the follow-up period using a validated scale from stage 0 ( none ) to stage 4 ( proliferative diabetic retinopathy ) , and percentage of telemedicine participants who would require referral to an eye care professional for follow-up care using a cutoff of moderate diabetic retinopathy or worse , the presence of macular edema , or an unable-to-determine result for retinopathy or macular edema .