Abstract
Purpose:
To evaluate structural- functional changes in the neural level of retina and cornea in type 1 diabetic (T1DM) patients without clinical evidence of retinopathy.
Methods:
30 T1DM patients (Age: 48±2 yrs; Duration diabetes: 28±3 yrs, HbA1c: 7.6±0.5 %) with no evidence of retinopathy and 15 aged matched healthy controls underwent detailed neurological (including Neuropathy Deficit Score (NDS)) and ophthalmic assessment including measurements of global and sectorial retinal nerve fibre layer (RNFL) thickness using Spectral Domain OCT (SD-OCT) (SPECTRALIS, Heidelberg Engineering) and retinal ganglion layer function (Flicker-Defined-Form (FDF)) using Heidelberg High Edge Perimetry (HEP). Corneal nerve fibre length (CNFL) and density (CNFD) were assessed using a corneal confocal microscope (Heidelberg HRT III) and corneal sensitivity was quantified using non- contact corneal aesthesiometer (NCCA).
Results:
There was a significant reduction in the global and sectorial RNFL (P=0.01) in diabetic patients compared to controls which correlated with the severity of peripheral neuropathy measured by NDS) (r= -0.403, P=0.01). FDF (P=0.01), CNFD (P=0.01), CNFL (P=0.01) and corneal sensitivity (P=0.01) were significantly reduced in T1DM compared to control subjects and they were significantly correlated with NDS.A greater proportion of T1DM patients showed abnormal retinal structure (RNFL-61%) and function (FDF-52%) compared to corneal structure (CNFD-32%) and function (NCCA-20%).
Conclusions:
Changes at the level of nerve fibre layers were observed in both the retina and cornea. However, the prevalence of abnormality was higher at the retina but the severity was more pronounced in the cornea especially in those patients without neuropathy. The results of this preliminary study suggest that structural changes in the cornea (Peripheral nerves) and in the retina (central nervous system) may occur in parallel and are correlated with functional changes.
Keywords: 498 diabetes •
482 cornea: epithelium •
499 diabetic retinopathy