To compare immediate laser pan-retinal photocoagulation (PRP) treatment of severe or very severe non proliferative diabetic retinopathy (NPDR) stage versus deferral of treatment until the appearance of any proliferative diabetic retinopathy (PDR) in rural and urban patients in China.

Interview data from some patients and survey data from ophthalmologists in the study hospitals will help determine acceptability of early treatment, and how to overcome barriers to increased use of this option.

China now has the world's largest number of diabetic persons. Population studies show that only 10% of Chinese rural-dwellers with DR receive therapy. The current standard approach to treatment of DR often requires patients to return for multiple examinations over years, before they reach trial-proven criteria for treatment. This long process is ill-suited to support good compliance with care in low-resource settings. Our recent published review suggests that earlier PRP treatment, which could reduce the burden of compliance, may be clinically effective and cost effective, but the current evidence base is insufficient to make a firm recommendation.

Inclusion Criteria:

• Adults aged >= 18 years with untreated DR at severe or very severe NPDR stage in either one or both eyes, according to the clinical opinion of the investigator.
• Sufficiently clear ocular media to allow visualization of the retina and retinal photography in either eye.
• Capable of giving informed consent.

Exclusion Criteria:

• DR at later stage of retinopathy than severe or very severe (eg, two or more of the 4-2-1 criteria are met) NPDR in either eye, but a patient may be enrolled if one eye has severe or very severe NPDR and the fellow eye has PRP-treated PDR and has been stable after treatment.
• Clinically significant macular edema in either eye.
• Dense cataracts or other media opacity preventing visualization of the retina in the eye.
• History of previous surgical or laser treatment for DR or other retinal conditions in a study eye, including history of anti-VEGF or corticosteroid injection or focal laser for DME within 6 months, or any history of scleral buckle, vitrectomy or other retinal detachment repair.
• History of other retinal vascular disorders including CRVO, CRAO, BRVO, BRAO in the study eye.
• Previous cataract or glaucoma surgery is specifically allowed if performed ≥ 6 weeks prior to enrollment.
• Pregnancy.
• Severe renal insufficiency treated with hemodialysis treatment, kidney transplant, pancreatic transplant, and intensive insulin therapy initiated within 4 months.
• Nystagmus, unable to cooperate with laser treatment.