Moderate-severe peripheral neuropathy in diabetes associated with an increased risk of dry eye disease.

SIGNIFICANCE This study establishes an increased risk of developing dry eye disease (DED) in patients with diabetic peripheral neuropathy using validated diagnostic criteria for both conditions. PURPOSE The disruption of ocular surface homeostasis has been associated with diabetes. However, it remains unclear if this association is independently influenced by peripheral neuropathy secondary to diabetes. This study aimed to investigate the clinical signs and symptoms of DED and their association with the severity of peripheral neuropathy in participants with type 2 diabetes. METHODS This prospective cross-sectional study recruited 63 participants with type 2 diabetes. All participants underwent a detailed assessment of DED using dry eye questionnaires (Ocular Surface Disease Index, Dry Eye Questionnaire-5), tear osmolarity, lipid layer thickness, noninvasive keratographic tear breakup time, phenol red thread test (PRT), and ocular surface staining. Corneal nerve morphology was imaged using corneal confocal microscopy. Based on the Total Neuropathy Scale, participants were stratified into no/mild (n = 48) and moderate/severe (n = 15) neuropathy groups. RESULTS Dry eye disease was diagnosed in 31 participants (50%) of the total cohort, and the odds of developing DED in the moderate/severe neuropathy group were four times (95% confidence interval, 1.10 to 13.80; p=0.030) higher compared with the no/mild neuropathy group. The Dry Eye Questionnaire-5 scores were significantly higher (p=0.020), and PRT values (p=0.048) and corneal nerve fiber length (p<0.001) were significantly reduced in the moderate/severe neuropathy group compared with the no/mild neuropathy group. In regression analysis, neuropathy scores were independently associated with PRT measurements (β = -0.333, p=0.023) and nerve fiber length (β = -0.219, p=0.012) while adjusting for age, gender, hemoglobin A1c, and duration of diabetes. CONCLUSIONS Type 2 diabetic patients with peripheral neuropathy have a risk of developing DED, which increases with the severity of neuropathy. The observation that worsening peripheral neuropathy is associated with reduced tear secretion suggests that it may contribute to aqueous insufficiency.