The efficacy of additional argon laser photocoagulation for persistent, severe proliferative diabetic retinopathy.

Twenty-three eyes with severe proliferative diabetic retinopathy had failed to show a satisfactory response to initial panretinal photocoagulation of approximately 3000 burns. A satisfactory response was defined as two or less retinopathy risk factors as defined by the diabetic retinopathy study (DRS). These eyes were treated with additional, extensive ablative laser therapy. Twelve of the 23 eyes showed a satisfactory response after an average of 7550 burns. Eleven eyes failed to show a satisfactory response after an average of 7985 burns. Forty-five percent of eyes that failed to show a satisfactory response suffered a severe decrease in visual acuity to count fingers or less. Additional extensive laser therapy can induce a satisfactory response in approximately 50% of resistant nonresponder eyes. Failure to respond to such therapy indicates a poor prognosis.