OBJECTIVE To examine the early changes of retinal sensitivity by fundus-related microperimetry after subthreshold micropulse diode laser photocoagulation (SMDLP) for diabetic macular oedema (DMO). METHODS Twenty-eight eyes of 28 patients with diffuse DMO were treated with SMDLP. The mean retinal sensitivity within the central 10 degrees measured with a fundus-related microperimeter, MP1, best corrected visual acuity (BCVA) in logarithm of minimum angle of resolution units, and optical coherence tomography-determined foveal thickness (FT) were examined before and 3 months after SMDLP. The pretreatment values of the retinal sensitivity, FT, BCVA, and funduscopic findings were compared with the corresponding values at 3 months after SMDLP. RESULTS At 3 months, the BCVA was significantly improved (P=0.03), and the FT was significantly reduced (P=0.0043). The mean retinal sensitivity within the central 10 degree, however, did not change significantly (P=0.70). The correlation between the changes in the retinal sensitivities and the decrease in the FT was not significant. The correlation between the changes in the retinal sensitivities and the BCVA was also not significant. CONCLUSIONS Significant improvements in retinal sensitivities within the central 10 degrees were not observed even though the decrease in FT and the improvement of BCVA were significant. On account of this difference of changes in retinal sensitivity and BCVA, the combination of retinal sensitivity by MP1 and BCVA may be beneficial in assessing the visual function from various angles after SMDLP for eyes with DMO.