AimsTo compare the efficacy of two power levels in the 577 nm sub-threshold micro pulse laser (SML) treatment of acute central serous chorioretinopathy (aCSC). MethodsA retrospective comparative study was conducted. A total of 65 patients (65 eyes) with aCSC were enrolled. Of which, 32 patients received low power treatment and 33 patients received high power treatment of 577-nm SML. Best-corrected visual acuity (BCVA), central macular thickness (CMT), fundus-monitored microperimetry and height of subfoveal choroidal thickness (SFCT) as well as subretinal fluid (SRF) were evaluated at baseline and 3 months. ResultsThe height of SFCT and retinal sensitivity in the low power treatment group was significantly better than that in the high power treatment group at 4 weeks (all p < 0.001). Mean BCVA improved from baseline to 3 months after treatments but with no significant difference between the two groups after 3 months (p > 0.05). In the low power group, the CMT decreased from 379.76 ± 139.23 μm at baseline to 176.56 ± 37.78 μm at 3 months, and in the high power group, the CMT decreased from 364.97 ± 143.08 at baseline to 191.77 ± 38.26 μm at 3 months. There was no significant difference at 3 months between the two groups (p > 0.05). Similar results were also found in term of SRF. ConclusionsTimely intervention with 577 nm SML with low power treatment can improve visual acuity, and included anatomic success without adverse events.