Among patients with type 2 diabetes who underwent bariatric surgery, reductions in BMI and HbA1c were linked with significant improvements in corneal nerve density/length, corneal sensation and clinical measures of peripheral neuropathy, according to these findings. Photo: UCLA Health. Click image to enlarge.

A new analysis, recently published in the journal Ocular Surface, demonstrated that bariatric surgery led to improvements in not only metabolic control of diabetes and weight loss, but also corneal nerve microstructure, corneal sensitivity and neuropathic symptoms. These findings, the study authors reported, suggest that bariatric surgery–related weight loss may partially reverse neuropathy among patients with diabetes.

This prospective longitudinal study was designed to assess progression/remission of corneal and peripheral neuropathy among patients with type 2 diabetes and high BMI who were undergoing sleeve or gastric bypass bariatric surgery.

Specifically, researchers from Auckland, New Zealand investigated potential associations between corneal nerve microstructure assessed by in vivo confocal microscopy of the cornea (IVCM), corneal sensitivity and clinical peripheral neuropathy following bariatric surgery.

The analysis included 29 patients with known type 2 diabetes for at least five years and scheduled bariatric surgery. Among the study population, patients had a mean BMI of 44.7kg/m² and 11 years duration of diabetes. Participants were assessed before bariatric surgery as well as at 12-, 26- and 52-weeks post-procedure.

Study authors reported in their Ocular Surface paper that corneal sub-basal nerve fiber length (CNFL) showed an increase from a baseline mean of 12.20 to 17.48 mm/mm² at 52 weeks. Additionally, corneal sensitivity threshold displayed a decrease over time, from a mean of 1.11 to 0.62. Data also revealed a significant improvement in clinical neuropathy scores from baseline.

“The current study revealed that bariatric surgery leads to an improvement not only of BMI and HbA1c, but also, corneal nerve microstructure, corneal sensitivity and neuropathic symptoms,” according to the researchers, who noted that this suggests a reversal of both small and large fiber diabetic neuropathy.

“To the best of our knowledge, this is one of the first studies to report changes in the cornea and retina, before and after bariatric surgery within the first year at various time-points. Notably, the regression of diabetic peripheral neuropathy could potentially be monitored using IVCM of the cornea as a biomarker,” they concluded in the journal Ocular Surface.