Phase 2 (2nd and 3rd years of follow up) is being conducted to collect data on, and generate hypotheses from, the long-term outcome of DME, irrespective of treatment received. Protocol visits will occur at 2 years + 8 weeks and 3 years + 8 weeks. During this phase of the study, therapies other than laser photocoagulation may be used to treat DME at the investigator's discretion. Because treatment other than photocoagulation will be allowed after one year, 'pure' results regarding outcomes with each laser technique cannot be obtained in all groups, but will be available in a subset of patients. The data are being collected at relatively low cost and no risk over and above usual care. Therefore, the collection of potentially hypothesis-generating data from exploratory analysis is justified and could be important in designing future studies. Interpretation of the results of the above analyses will be complicated by the lack of a standardized protocol with regard to which patients receive treatment and what treatment is provided. Therefore, the results will be interpreted with caution.