Macular thickness in patients with type 2 diabetes without clinical diabetic retinopathy: a cross-sectional study
DOI:
https://doi.org/10.31288/Ukr.j.ophthalmol.202634754Keywords:
diabetic retinopathy, diabetes mellitus, macula, optical coherence tomography, central retinal thicknessAbstract
Background. Diabetic retinopathy (DR) is a major cause of visual impairment. Optical coherence tomography (OCT) enables the detection of early retinal structural changes before clinically evident retinopathy; however, findings on macular thickness in diabetes without retinopathy remain inconsistent, and data from Iraqi populations are limited. This study aimed to evaluate macular thickness in Iraqi patients with diabetes mellitus (DM) without clinical DR.
Methods. This observational, analytical cross-sectional study was conducted from January 2025 to January 2026 and included 53 participants (26 patients with DM without DR and 27 healthy controls). All participants underwent a standardized ophthalmic examination. Macular thickness was measured using spectral-domain OCT (Topcon 3D OCT). Only the right eye was analyzed to avoid inter-eye correlation. Central subfield macular thickness (CSMT) and ETDRS-based regional thickness were recorded.
Results. The diabetes group was significantly older than controls (p < 0.001). CSMT differed significantly between groups in unadjusted analysis (p < 0.0001). However, after adjustment for age, the direction of this association was reversed, indicating a strong confounding effect. No significant differences were observed in the parafoveal region. In the perifoveal region, the nasal subfield was significantly thicker (p = 0.004), and this difference remained significant after age adjustment (p = 0.009), while the temporal difference was not significant after adjustment. ROC analysis showed high discriminative ability of CSMT (AUC = 0.965), with a cutoff of ≤236 µm yielding high sensitivity (96.2%) and specificity (88.9%).
Conclusions. Patients with DM without clinical DR demonstrated alterations in macular thickness, including localized nasal perifoveal thickening, suggesting early retinal structural changes detectable by OCT. While CSMT demonstrated strong discriminative performance, its sensitivity to age-related effects limits its reliability as a standalone biomarker. These findings are exploratory and require confirmation in larger, well-controlled studies.
References
Zhang J, Zhang J, Zhang C, Zhang J, Gu L, Luo D, et al. Diabetic Macular Edema: Current Understanding, Molecular Mechanisms and Therapeutic Implications. Cells. 2022;11(21):3362. https://doi.org/10.3390/cells11213362
Kalaw FGP, Sharma P, Walker E, Borooah S. Differences in macular thickness associated with peripheral retinal vessel whitening in diabetic patients. Sci Rep. 2024;14(1):19881. https://doi.org/10.1038/s41598-024-68839-0
Chondrozoumakis G, Chatzimichail E, Habra O, Vounotrypidis E, Papanas N, Gatzioufas Z, et al. Retinal Biomarkers in Diabetic Retinopathy: From Early Detection to Personalized Treatment. J Clin Med. 2025;14(4):1343. https://doi.org/10.3390/jcm14041343
Badaró E, Novais E, Prodocimo LM, Sallum JM. Spectral-domain optical coherence tomography for macular edema. ScientificWorldJournal. 2014;2014:191847.https://doi.org/10.1155/2014/191847
Szeto SK, Lai TY, Vujosevic S, Sun JK, Sadda SR, Tan G, et al. Optical coherence tomography in the management of diabetic macular oedema. Prog Retin Eye Res. 2024;98:101220. doi: 10.1016/j.preteyeres.2023.101220. Erratum in: Prog Retin Eye Res. 2025;104:101319.https://doi.org/10.1016/j.preteyeres.2024.101319
Duncan BB, Magliano DJ, Boyko EJ. IDF Diabetes Atlas 11th edition 2025: global prevalence and projections for 2050. Nephrol Dial Transplant. 2025;41(1):7-9. https://doi.org/10.1093/ndt/gfaf177
Mandloi G, Jain A, Sharma A, Tirkey ER, Jain S. Evaluation of Spectral Domain OCT Changes Following Anti-VEGF Therapy in Diabetic Macular Edema. J Pharm Bioallied Sci. 2026;18(Suppl 1):S212-S214. https://doi.org/10.4103/jpbs.jpbs_1238_25
Tang Z, Chan MY, Leung WY, Wong HY, Ng CM, Chan VTT, et al. Assessment of retinal neurodegeneration with spectral-domain optical coherence tomography: a systematic review and meta-analysis. Eye (Lond). 2021;35(5):1317-1325. https://doi.org/10.1038/s41433-020-1020-z
Vaughan M, Denmead P, Tay N, Rajendram R, Michaelides M, Patterson E. How early can we detect diabetic retinopathy? A narrative review of imaging tools for structural assessment of the retina. Graefes Arch Clin Exp Ophthalmol. 2025;263(9):2413-2425.https://doi.org/10.1007/s00417-025-06828-3
Dai Y, Zheng D, Zhao J, Wang K, Fu B, Xu Z, et al. Macular Neural and Microvascular Alterations in Type 2 Diabetes Without Retinopathy: A SS-OCT Study. Am J Ophthalmol. 2024;262:229-236. https://doi.org/10.1016/j.ajo.2024.02.034
Peto T, Evans RN, Reeves BC, Harding S, Madhusudhan S, Lotery A, et al. Long-term Retinal Morphology and Functional Associations in Treated Neovascular Age-Related Macular Degeneration: Findings from the Inhibition of VEGF in Age-Related Choroidal Neovascularisation Trial. Ophthalmol Retina. 2022;6(8):664-675. https://doi.org/10.1016/j.oret.2022.03.010
Toprak I, Fenkci SM, Fidan Yaylali G, Martin C, Yaylali V. Early retinal neurodegeneration in preclinical diabetic retinopathy: a multifactorial investigation. Eye (Lond). 2020;34(6):1100-1107. https://doi.org/10.1038/s41433-019-0646-1
Wei Q, Qiu W, Liu Q, Jiang Y. Relationship Between Risk Factors and Macular Thickness in Patients with Early Diabetic Retinopathy. Int J Gen Med. 2022;15:6021-6029. https://doi.org/10.2147/IJGM.S366348
Shah J, Tan B, Wong D, Abdul Gani NFB, Hu Q, Liu X, et al. Evaluation of thickness of individual macular retinal layers in diabetic eyes from optical coherence tomography. Sci Rep. 2024;14(1):17909. https://doi.org/10.1038/s41598-024-68552-y
Boned-Murillo A, Fernández-Espinosa G, Orduna-Hospital E, Díaz-Barreda MD, Sánchez-Cano A, Sopeña-Pinilla M, et al. Changes in Inner Retina Thickness and Macular Sensitivity in Patients with Type 2 Diabetes with Moderate Diabetic Retinopathy. Biomedicines. 2023;11(11):2972. https://doi.org/10.3390/biomedicines11112972
De Clerck EEB, Schouten JSAG, Berendschot TTJM, Goezinne F, Dagnelie PC, Schaper NC, et al. Macular thinning in prediabetes or type 2 diabetes without diabetic retinopathy: the Maastricht Study. Acta Ophthalmol. 2018;96(2):174-182.https://doi.org/10.1111/aos.13570
Karti O, Nalbantoglu O, Abali S, Ayhan Z, Tunc S, Kusbeci T, et al. Retinal Ganglion Cell Loss in Children With Type 1 Diabetes Mellitus Without Diabetic Retinopathy. Ophthalmic Surg Lasers Imaging Retina. 2017;48(6):473-477. doi: 10.3928/23258160-20170601-05. Erratum in: Ophthalmic Surg Lasers Imaging Retina. 2017;48(7):530. https://doi.org/10.3928/23258160-20170630-02
Boned-Murillo A, Diaz-Barreda MD, Ferreras A, Bartolomé-Sesé I, Orduna-Hospital E, Montes-Rodríguez P, et al. Structural and functional findings in patients with moderate diabetic retinopathy. Graefes Arch Clin Exp Ophthalmol. 2021;259(12):3625-3635.https://doi.org/10.1007/s00417-021-05277-y
Viganò I, Galbiati S, Aragona E, Gabellini D, Lattanzio R, Pedon V, et al. Diabetes-Driven Retinal Neurodegeneration: Its Role in the Pathogenesis of Diabetic Retinopathy. Biomedicines. 2025;13(6):1328. https://doi.org/10.3390/biomedicines13061328
Lin CY, Sheen YJ, Chen HM, Lu YA, Chen JP, Huang HE, et al. Vulnerable parafoveal microcirculation quadrant in patients with type 2 diabetes mellitus. Sci Rep. 2025;15(1):1237. https://doi.org/10.1038/s41598-024-85021-8
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