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¹Aydın Atatürk Devlet Hastanesi, Göz Hastalıkları, Aydın, Uz. Dr.
²Ege Üniversitesi Tıp Fakültesi, Göz Hastalıkları A.D., İzmir, Prof. Dr.
³Ege Üniversitesi Tıp Fakültesi, Göz Hastalıkları A.D., İzmir, Doç. Dr. Purpose: To evaluate macular thickness and retinal nerve fiber thickness measurements with optic coherence tomography in type 1 and type 2 diabetes mellitus patients without retinopathy and to compare these results with those of a normal group.
Materials and Methods: In patients with 50 type 1 and 50 type 2 diabetes mellitus without retinopathy and 50 volunteers without diabetes mellitus were enrolled in this study. Best corrected visual acuity of all patients and all volunteers was determined and detailed anterior and posterior segment examinations were performed. Intraocular pressures were evaluated using a Goldman aplanation tonometer. Each eye of the patients and normal group was scanned with optic coherence tomography using fast macular thickness and macular thickness protocols. Retinal thickness and total macular volume were calculated automatically in the central 1 mm area using the retinal thickness/volume protocol. The groups were compared to each other according to horizontal scans of the central 1 mm area and total macular volume measurements. Retinal nerve fiber layer thickness measurements of 50 eyes of each 25 type 1 and 25 type 2 diabetes mellitus patients and 25 volunteers were done using the retinal nerve fiber layer ‘thickness average’ method and evaluated in superior, temporal, nasal, and inferior areas.
Results: Retinal thickness was 186.02±30.138 μ (112-272) in type 1 diabetes mellitus patients, 195.92±25.44 μ (118-274) in type 2 diabetes mellitus patients, and 195.92±28.82 μ (136-295) in the normal group in the central 1 mm area. Retinal thickness average was significantly lower in type 1 diabetes mellitus patients than in the other 2 groups (p=0.017). Total macular volume was 6.81±0.58 mm³ (3.5-7.9) in type 1 diabetes mellitus patients, 6.86±0.51 mm³ (4.9-9.2) in type 2 diabetes mellitus patients, and 7.03±0.65 mm³ (5-10) in the normal group. Total macular volume in type 1 diabetes mellitus patients was lower than in type 2 diabetes mellitus patients and the control group, and the difference between type 1 diabetes mellitus patients and the control group was significant (p=0.023). Retinal nerve fiber layer thickness was 77.72±14.43 μm (48-125) in type 1 diabetes mellitus patients, 68.08±15.72 μm (42-108) in type 2 diabetes mellitus patients, and 73.74±25.25 μm (38-194) in the control group in the nasal area. The difference between type 1 diabetes mellitus patients and type 2 diabetes mellitus patients in the nasal area was significant (p=0.043).
Conclusion: Retinal thickness measurements in the horizontal area were significantly lower in type 1 diabetes mellitus patients without retinopathy than in type 2 diabetes mellitus patients without retinopathy and the control group. Total macular volume difference between type 2 diabetes mellitus patients and the control group was significant. Retinal nerve fiber layer thickness was less than the other 2 groups in all areas and in average values in type 2 diabetes mellitus patients, but only the values in the nasal area were significantly lower between type 2 and type 1 diabetes mellitus patients. Keywords : Retinal thickness, retinal nerve fiber layer thickness, optic coherence tomography