To compare the changes in central subfield macular thickness (CSMT) using optical coherence tomography (OCT) after cataract surgery and to evaluate the risk factors of macular edema.

The retrospective study consisted of 55 eyes of 50 patients who underwent phacoemulsification. All of these eyes were assessed by OCT and best-corrected visual acuity, and fundus examination before and one month after surgery. CSMT was measured based on a central thickness of 1 mm, and macular edema was defined as an increase of CSMT in 30% or more after surgery than before.

CSMT significantly increased by 22.2 ± 47.10 µm at 1 month after cataract surgery in the operated eye compared with the fellow eye ( p = 0.01). The diabetic retinopathy group and hypertensive group showed more significant increases than the non-diabetic and non-hypertensive group. Macular edema developed in seven of 55 eyes (12.7%), and they consisted of five moderate or more severe diabetic retinopathies and two epiretinal membrane. Four weeks after surgery, the macular edema group showed more decrease in visual acuity; however, the CSMT was not correlated with the duration of diabetes mellitus, types of surgical incision, HbA1c or other factors.

CSMT increased in the operated eye after cataract surgery, especially in eyes with diabetic retinopathy and hypertension. Moderate or more severe diabetic retinopathy and macular lesions such as epiretinal membrane increased the risk of macular edema after cataract surgery.