PURPOSE: Some clinical trials that proved the benefits of anti-VEGF therapy for diabetic macular edema (DME) based retreatment decisions on visual acuity and time-domain ocular coherence tomography (TD-OCT) central subfield thickness changes since the last treatment. This study assessed the impact of TD-OCT followed by spectral domain (SD)-OCT on as needed treatment decision-making in the management of DME with anti-VEGF medications. METHODS: Patients previously treated for DME with anti-VEGF medications in the Retina Division of the Wilmer Eye Institute, following an institutional review board-approved informed consent process, underwent clinical examination, TD-, and SD-OCT imaging. Their retina specialists recorded whether additional anti-VEGF therapy was recommended and their level of certainty in the decision after performing a clinical examination and reviewing a TD-OCT, and then again after reviewing a SD-OCT. RESULTS: Data were collected for 129 treatment decision pairs involving 67 eyes from 46 subjects. Nonconcordant decisions occurred in 9 (7%) treatment decision pairs. In 7 of these (5%, 95% confidence interval [CI]: 2%-11%), the addition of SD-OCT changed the retina specialist's decision from not recommending to recommending retreatment. The addition of SD-OCT increased the certainty of the retina specialist in 36% (95% CI: 27%-45%) of all treatment decision pairs. CONCLUSIONS: Spectral-domain OCT does not appear to change the ultimate treatment decision or increase the level of certainty of the retina specialist relative to TD-OCT in most cases of DME under anti-VEGF management in clinical practice. The few nonconcordant decisions appear to trend toward recommending more anti-VEGF therapy following SD-OCT.