Materials and Methods: One hundred seventy-five eyes of 115 patients diagnosed as DME in our retina clinic between April 2009-June 2014 were included. Best-corrected visual acuity (BCVA) and central macular thickness (CMT) of the patients were recorded before and after the treatment of intravitreal ranibizumab. The patients were classified into 3 groups according to the foveal cyst sizes on the baseline spectral-domain optical coherence tomography (SD-OCT) findings (Group 1; ?300 mm, Group 2; 300-600 mm, Group 3; ?600 mm).

Results: The mean age of the patients was 60.24±8.49 (36-81) years and the mean of follow-up time was 22.64±12.03 (4-50) months. The number of enjections administered to the groups was similar (p>0.05). A significant improvement in visual acuity was provided in all 3 groups treated with ranibizumab. There wasn?t any significant difference in BCVA between the groups in both baseline and final examinations. A significant reduction in CMT with ranibizumab treatment was found in all 3 groups. There was significant difference between the groups before the treatment, but there wasn?t after ranibizumab treatment. There was no correlation between BCVA and the cyst size (r=0.138, p=0.196) and CMT (r=0.102, p=0.115).

Conclusion: It was found that the cyst size is not the only prognostic factor in the response to ranibizumab treatment with respect to visual acuity and macular thickness in DME. Keywords : Central macular thickness, cyst size, diabetic macular edema, spectral-domain optical coherence tomography