Changes in corneal and lens autofluorescence and blood glucose levels in diabetics: parameters of blood glucose control.

PURPOSE

We investigated corneal and lens autofluorescence in patients with proliferative diabetic retinopathy (PDR) to determine a correlation between the two parameters and blood glucose levels and HbA1c.

METHODS

Corneal and lens autofluorescence levels in 17 PDR patients and 8 healthy controls were measured with a fluorophotometer fitted with an anterior segment adapter. We measured the lower blood glucose level (BS1), corneal autofluorescence (CA1), and lens autofluorescence (LA1) simultaneously and the higher blood glucose level (BS2), CA2, and LA2 simultaneously on the same day. We defined parameter changes as: delta BS = BS2 - BS1, delta CA = CA2 - CA1, and delta LA = LA2 - LA1.

RESULTS

Corneal and lens autofluorescence significantly increased in the patients, compared with the controls (p < 0.001). Lens autofluorescence had a significant positive correlation with HbA1c (r = 0.656, p < 0.01) in the patients. delta CA (ngEq/ml) correlated significantly with delta BS (mg/dl) (r = 0.631, P < 0.01).

CONCLUSIONS

Results suggest that lens autofluorescence might represent the long-term control of diabetes, and corneal autofluorescence levels may represent short-term changes in the blood glucose level, because hyperglycemia accelerates with increasing corneal autofluorescence in PDR patients. Corneal and lens autofluorescence may be related to the breakdown of the blood-aqueous barrier.