OBJECTIVE To investigate the effect of postoperative systemic steroid therapy on the incidence and duration of the subretinal fluid (SRF) and its correlation with the visual outcome after scleral buckle surgery for macula-off rhegmatogenous retinal detachment. METHODS Prospective interventional study of sixty patients with macula-off rhegmatogenous retinal detachment who undertook scleral buckle surgery. Those patients who had recurrent retinal detachment, proliferative preretinal membrane, or primary surgical failure were excluded. Patients were assigned to Group 1 (with prescription of oral prednisolone for 3 days postoperatively) and Group 2 (with no such prescription).Furthermore, patients in Group 1 were subdivided into Group 1A (0.5 mg prednisolone/kg)and Group 1B (1 mg prednisolone/kg) according to the dosage of prednisolone. Patients were followed-up initially 1 week and 2 weeks after surgery and then on a monthly basis for at least 1 year. After the operation, all patients had corrected visual acuity and also received examinations of indirect ophthalmoscopy and optical coherence tomography. We compared the incidence, duration of SRF, and the correlation with the visual outcome between the groups. RESULTS Lower incidence of SRF was noted in Group 1 than in Group 2 (56.7% vs. 80%;P = 0.052), and the duration of SRF was significantly shorter in Group 1 than in Group 2 (218 days vs. 286 days; P = 0.039). There was no significant difference in the final BCVA between the two groups. However, patients in Group 1 had greater improvements of BCVA 1 year after operation (13 lines vs. 7 lines in Groups 1 and 2, respectively; P = 0.026). Statistically,there were no difference between Groups 1A and 1B, in terms of the incidence of SRF,duration of SRF, final BCVA, and improvement of BCVA. CONCLUSIONS Postoperative systemic steroid treatment may decrease the incidence of SRF and facilitate the absorption of SRF. Patients treated with steroids had greater improvement of BCVA.