Introduction: The purpose of this study was to clinically diagnose and quantify the Diabetic macular oedema in terms of Central Foveal Thickness (CFT) and Central Subfield Thickness (CST) on a 3D-OCT scan and its correlation with the visual acuity of subject patients enrolled in the study. Aims: __ampersandsignbull; To Diagnose Diabetic macular oedema and its correlation with Visual Acuity. __ampersandsignbull; To Quantify Diabetic macular oedema in terms of Central Foveal Thickness and Central Subfield Thickness. Methodology: In total 50 patients that met the inclusion and exclusion criteria were enrolled on the study, All patients underwent detailed ophthalmological examination. A complete ophthalmic examination including Visual acuity, Intraocular pressure, Anterior segment examination using slit-lamp biomicroscopy, dilated fundus examination through spectral-domain 3-D OCT and was assessed for the presence of diabetic macular oedema, changes in the fundus and its correlation with CFT (central foveal thickness) and CST (Central Subfield Thickness) were measured by OCT. Result: Mean BCVA was 0.59__ampersandsignplusmn; 0.58 ranging from 0.02 to 3.0 on Log MAR. Macular thickness measured as CFT had a mean of 353.5__ampersandsignplusmn;152.5 __ampersandsignmicro; ranging 202 to 765 microns, whereas CST showed a mean of 370.5__ampersandsignplusmn;144.4 microns ranging 231 to 770 microns. The BCVA had a moderate correlation with CST. Correlation of BCVA was better with CFT(spearman__ampersandsignrsquo;s r=0.532;p=0.000)than that of CST(spearman__ampersandsignrsquo;s r=0.586;p=0.000). Conclusion: We concluded that CFT is more accurate to predict the prognosis of visual outcome in cases of Diabetic macular oedema suggesting the worst visual outcome in cases with diffuse retinal thickening with increased CFT.