As part of the prospective, non-interventional OCEAN study, the ORCA module evaluated physicians' spectral domain optical coherence tomography (SD-OCT) image interpretations in the treatment of diabetic macular oedema (DME) or macular oedema (ME) secondary to retinal vein occlusion (RVO). Presence of intraretinal fluid (IRF) and/or subretinal fluid (SRF) was evaluated independently by physicians and reading centres (RCs) on 1612 SD-OCT scans of 133 patients diagnosed with either DME or ME secondary to RVO. Agreement between physicians and RCs was calculated for both cohorts individually and as a combined ME cohort. Physicians' treatment decisions were analysed related to the results of the OCT-evaluations. For the combined ME cohort, presence of IRF/SRF was recorded by RCs in 792/1612 (49.1%) visits and by physicians in 852/1612 (52.9%) visits, with an agreement regarding presence or absence of foveal fluid in 70.4% of cases. In 64.4% (510/792) of visits with RC-detected foveal IRF and/or SRF no injection was given. In 30.3% of these visits with foveal fluid no reason was identified for a 'watch and wait' approach indicating possible undertreatment. BCVA deterioration was seen in a quarter of these eyes at the following visit. Despite good agreement between physicians and RCs to recognize SRF and IRF, our data indicate that omitting injections despite foveal involvement of fluid is frequent in routine clinical practice. This may put patients at risk of undertreatment, which may negatively impact real-life BCVA outcomes. www. gov , identifier NCT02194803.