Background: Ophthalmologists treat diabetic macular edema before cataract surgery to reduce possible complications. Despite improvements in diagnostic techniques, whether cataract surgery per se causes the progression of diabetic retinopathy with macular edema remains unclear. This study aimed to evaluate the impact of phacoemulsification on the central retina and its correlation with diabetes compensation as well as changes in the retina before surgery.
Methods: Thirty-four type 2 diabetes mellitus patients who underwent phacoemulsification cataract surgery were included in this prospective longitudinal study. Of them, 29.4% had macular edema before surgery, and 70.6% had a normal macular structure. All patients underwent ophthalmic examinations, including optical coherence tomography angiography, at baseline and at one and three months after surgery. The Mann-Whitney test was performed to compare the area of the foveal avascular zone, perimeter of the foveal avascular zone, and mean vascular density in the para- and perifoveal deep and superficial capillary plexuses. All parameters were measured before and at one and three months after surgery. Multiple linear regression models with adjustments for glycated hemoglobin and duration of diabetes mellitus were constructed to assess the association between the area of the foveal avascular zone and diabetic macular edema.
Results: Significant differences in the area of the foveal avascular zone, perimeter of the foveal avascular zone, and perifoveal density in the deep capillary plexus were observed at all three time points. In the fully adjusted linear regression model, those without diabetic macular edema had a reduced probability for changes in the foveal avascular zone at one and three months after surgery (effect estimate β = -0.20 [95% CI -0.31; -0.09] and β = -0.13 [-0.22; -0.03] for one and three months, respectively) compared with those with diabetic macular edema.
Conclusions: Cataract surgery itself does not cause significant and permanent increase in diabetic macular edema three months post-surgery. On the contrary, in a group with diabetic macular edema before the surgery, central retinal thickness tended to stabilize three months after surgery. If the duration of diabetes is shorter and diabetes is better compensated, the possibility of changes in the foveal avascular zone is reduced.
Keywords: diabetic maculopathy; diabetic retinopathy; foveal avascular zone; optical coherence tomography angiography; phacoemulsification cataract surgery; vessel density.