Retinal neurodegeneration in metabolic syndrome: a spectral optical coherence tomography study

? AIM: To evaluate the effects of metabolic syndrome (MetS) on retinal neurodegeneration by optical coherence tomography (OCT). ? METHODS: Patients diagnosed as MetS were compared with the age and sex-matched healthy control group (CG). Waist circumference measurements, fasting serological biochemical tests, and systemic blood pressures of all participants were evaluated. The MetS group was divided into 3 subgroups according to the number of MetS components: hypertension, diabetes mellitus, dyslipidemia (low-, high-density lipoprotein, hypertriglyceridemia), and visceral obesity findings; 3-component MetS3, 4-component MetS4, and all-component MetS5. All patients underwent complete eye examination and spectral OCT retinal imaging. ? RESULTS: Totally 58 eyes of 58 patients were included in the MetS group and 63 eyes of 63 age and sex-matched healthy subjects were included in CG. MetS group was composed of 22 subjects in MetS3, 21 subjects in MetS4, and 15 subjects in the MetS5 subgroup. Mean foveal thickness (MetS, 218.7 +/- 23.1 pm vs CG, 228.8 +/- 21.9 pm, P=0.015), mean inferior (MetS, 283.4 +/- 17.0 pm vs CG, 288.7 +/- 38.4 pm, P=0.002), superior (MetS, 287.0 +/- 18.5 pm vs CG 297.3 +/- 17.1 pm, P=0.001), nasal (MetS 287.3 +/- 16.7 pm vs CG 297.9 +/- 13.9 pm, P=0.000) and temporal (274.5 +/- 17.6 pm vs CG 285.6 +/- 13.6 pm, P=0.000) thickness in the 3 mm Early Treatment of Diabetic Retinopathy Study (ETDRS) circle was significantly lower in the MetS group. There was no statistically significant difference in the mean inferior, superior, nasal, and temporal thickness of 6 mm ETDRS circle, total macular volume, peripapillary and macular retinal nerve fiber layer, macular ganglion cell layer with inner plexiform layer, and ganglion cell complex. No statistically significant difference was found in these values between the MetS3, MetS4, and the MetS5 groups. ? CONCLUSION: A significant reduction in central macular region thickness in MetS is detected and macular thickness is more susceptible to MetS induced neurodegeneration than peripapillary retinal nerve fiber layer.