Aim: - The aim of this study is to compare central macular thickness changes after un complicated phacoemulsification in diabetic versus Non diabetic patients by using optical coherence tomography (OCT).
 Patient and Methods: This  prospective comparative randomized study included 50 eyes who were scheduled for cataract surgery by phacoemulsification in ophthalmic department, Sohag university Hospital ,in period from  March 2016 to  June 2017.These patients were divided into two main groups ,Group1 includes 25 eyes for diabetic patints and Group 2 includes 25 eyes for non diabetic patients. A comparison between two groups was done.The following was done for each patient in this study
Detailed history including  age,gender, presence of diabetes and its duration,history of previous ocular surgery,history of previous treatment in diabetic patients..
.Conclusion: Our results suggest that Diabetes influences the central macular thickness in diabetic pateints, who are more liable to changes in central macular thickness after cataract surgery even if uncomplicated
OCT is valuable, non invasive , reproducible device to detect Pre&Post operative changes in  macular thickness and it represents the single most important diagnostic and prognostic tool in management of macular oedema  .