Tear Levels of Insulin-Like Growth Factor Binding Protein 3 Correlate With Subbasal Nerve Plexus Changes in Patients With Type 2 Diabetes Mellitus

• Published in: Investigative ophthalmology & visual science Vol. 58; no. 14; pp. 6105 - 6112
• Main Authors: Stuard, Whitney L., Titone, Rossella, Robertson, Danielle M.
• Format: Journal Article
• Language: English
• Published: United States The Association for Research in Vision and Ophthalmology 01.12.2017
• Subjects: Clinical and Epidemiologic Research
• ISSN: 1552-5783; 0146-0404; 1552-5783
• DOI: 10.1167/iovs.17-22425

This study investigated the expression of insulin-like growth factor binding protein-3 (IGFBP-3) in basal tears of patients with type 2 diabetes mellitus compared to nondiabetic controls; and correlated tear levels of IGFBP-3 with morphologic changes in the subbasal nerve plexus and density of basal corneal epithelial cells. This was a single visit, cross-sectional study. Diabetic and control subjects were matched for age, sex, smoking status, and body mass index. Tear levels of IGFBP-3 were measured using ELISA. Corneal nerve and basal epithelial cell changes were measured using in vivo confocal microscopy. Tear levels of IGFBP-3 were 3.5-fold higher in those with diabetes. Patients with diabetes also showed a reduction in nerve fiber layer, nerve branch density, and corneal basal epithelial cell density. There was no significant difference in corneal sensitivity. IGFBP-3 levels were highly correlated with nerve fiber length and branch density; while hemoglobin (Hb)A1c was only moderately correlated. There were no significant differences in the clinical or subjective signs of dry eye between groups, indicating that tear levels of IGFBP-3 and corneal nerve changes were not due to the presence of mild dry eye. These findings indicate that tear levels of IGFBP-3 are more tightly correlated to nerve fiber changes in diabetes than HbA1c. Future studies that stratify the severity of diabetic disease with tear levels of IGFBP-3 are needed to validate this finding.