The subclassification and long-term prognosis of preproliferative diabetic retinopathy

We followed up 54 patients (95 eyes) with preproliferative diabetic retinopathy (PPDR) for at least 2 years, and then evaluated the proportion developing proliferative diabetic retinopathy (PDR), and the period from diagnosis of PPDR until the development of PDR.

We divided the 95 eyes affected by PPDR into 75 eyes with mild-type and 20 eyes with moderate-type based on our previously proposed subclassification, and evaluated long-term (2 or more years) prognosis.

The proportion developing PDR was 24% in mild-type and 60% in moderate-type. The average period from diagnosis of PPDR until the development of PDR was 6 years and 5 months in mild-type, 2 years in moderate-type. The cumulative occurrence rates of PDR at 2, 5, and 10 years were estimated to be 0%, 14%, and 39% in mild-type and 35%, 58%, and 79% in moderate-type, respectively. The proportion developing PDR was significantly higher and the average period until PDR development significantly shorter in moderate than in mild-type. In mild-type eyes, the rate of progression to moderate-type was 56% and further progression from moderate-type to PDR occurred in 43%.

The above results again confirm the usefulness of our subclassification, and also provide valuable information about the long-term prognosis of PPDR.