[Relationship between macular morphology and visual function in diabetic macular edema]

To investigate the changes and relation between macular morphology and macular visual function in different degrees of diabetic macular edema.

Seventy-eight eyes of 41 diabetic retinopathy patients were included and graded for diabetic macular edema as follows:31 were graded as no macular edema (NE), 26 as non-clinically significant macular edema (NCSME), and 21 as clinically significant macular edema (CSME). Best corrected visual acuity, macular sensitivity, and macular thickness of all included eyes were examed and quantified. Macular sensitivity and retinal fixation were investigated with MP-1 microperimetry. Optical coherence tomography (OCT) was used to quantify macular thickness.

Macular thickness significantly increased and macular sensitivity markedly decreased from the NE to the CSME group (P < 0.01), Visual acuity obviously decreased in the CSME group (P < 0.01) compared to the NE and NCSME group, but there was no statistical difference between the NE group and NCSME group. Retinal fixation type was not significantly different among three groups. Visual acuity and macular sensitivity correlated significantly in these three groups (r = -0.751, P < 0.01; r = -0.583, P < 0.01; r = -0.679, P < 0.01). The correlations were noted between retinal sensitivity and macular thickness as well as between visual acuity and macular thickness in the CSME group (r = -0.465, P < 0.05; r = 0.599, P < 0.01), but not in the NE group or in the NCSME group.

Patients will have retinal morphologic and functional changes in early stage of DME, both of which are significantly related as the disease develops. MP-1 microperimetry proved to be consistent with VA in the evaluation of visual function, and may be more sensitive to investigate the changes of macular visual function in the early stage of macular edema.