Corneal nerve fibre damage precedes diabetic retinopathy in patients with Type 2 diabetes mellitus

• Published in: Diabetic medicine Vol. 31; no. 4; pp. 431 - 438
• Main Authors: Bitirgen, G., Ozkagnici, A., Malik, R. A., Kerimoglu, H.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.04.2014; Blackwell; Wiley Subscription Services, Inc
• Subjects: Aged; Biological and medical sciences; Case-Control Studies; Cell Count; Cornea - innervation; Corneal Keratocytes - cytology; Diabetes; Diabetes Mellitus, Type 2 - pathology; Diabetes. Impaired glucose tolerance; Diabetic Retinopathy - pathology; Disease Progression; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Endothelial Cells - cytology; Epithelial Cells - cytology; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Microscopy, Confocal; Middle Aged; Nerve Fibers - pathology; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Endocrinopathy; Type 2 diabetes; Human; Obesity; Retinopathy; Nutrition; Nutrition disorder; Patient; Metabolic diseases; Corneal nerve; Eye disease; Nerve fiber; Endocrinology; Nutritional status
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/dme.12324

Aims To quantify the morphological alterations in corneal nerve fibres and cells in patients with Type 2 diabetes mellitus in relation to the severity of diabetic retinopathy. Methods One hundred and thirty‐two eyes of 132 patients with Type 2 diabetes and 32 eyes of 32 healthy control subjects were evaluated with in vivo corneal confocal microscopy. Patients with diabetes were classified into three groups: patients without diabetic retinopathy, patients with non‐proliferative diabetic retinopathy and patients with proliferative diabetic retinopathy. Anterior and posterior stromal keratocyte, endothelial cell and basal epithelial cell densities and sub‐basal nerve fibre structure were evaluated. Results Significant reductions in basal epithelial cell, anterior stromal keratocyte and endothelial cell densities were observed only in patients with diabetic retinopathy. However, nerve fibre density, nerve branch density and nerve fibre length were reduced in patients without diabetic retinopathy and worsened progressively with increasing severity of retinopathy. Conclusions Corneal cell pathology occurs in patients with diabetic retinopathy, but corneal nerve fibre damage seems to precede the development of diabetic retinopathy. What's new? Diabetic retinopathy is considered to be the earliest microvascular complication. This study demonstrated significant alterations in the corneal cells and nerve fibres of patients with diabetes and in particular showed that corneal nerve loss may precede diabetic retinopathy.