Abstract
Purpose: :
To evaluate concordance between results offered by corneal confocal microscopy (CFM) and those deriving from a clinical and electromyographycal evaluation of diabetic patients with distal symmetric polyneuropathy (DSP) and to study the relationship between corneal nerves damage and other variables (symptoms, age and years of disease).
Methods: :
In a period of 7 months 62 patients were enrolled (45 diabetic cases-group 1 and 17 age matched non-diabetic control subjects-group 2). All diabetic patients underwent a neurological examination to evaluate the presence or the absence of symptoms and to perform an EMG. This examination allowed a classification of neuropathy in absent (DSP 0), mild (DSP 1), moderate (DSP 2) and severe (DSP 3). Afterwards corneal sub-basal nerve plexus fibers of both diabetic and non-diabetic subjects were studied using CFM. Only one eye of each patient was used randomizing with a coin; three images for patient were reviewed using the software "imageJ" and the parameter we considered was "nerve fiber length"(NFL).
Results: :
The mean age in group 1 was 68,2 ± 8,5 and in group 2 it was 68,2 ± 7,3. The mean duration of disease was 7,8 years. Data analysis showed no significant differences between NFL of DSP 0 patients and NFL of non-diabetic subjects (p> 0.05), while this difference was significant between these two groups and diabetic patients which had EMG examination positive for neuropathy (DSP 1, 2, 3). Additionally, we couldn't demonstrate differences in NFL of mild, moderate and severe neuropathic patients; a significant correlation was found between corneal damage and presence of symptoms. No correlations were found between age of patients, duration of diabetes and NFL.
Conclusions: :
CFM confirmed to be an important tool for a rapid, repeatable, non-invasive evaluation of diabetic neuropathy. Our study showed a significant correlation between EMG and NFL evaluated by this technique. While showing the presence or absence of neuropathy, CFM is not sensitive enough for differentiating among the different stages. For this purpose EMG should still be considered the gold standard. Further studies are necessary to evaluate relationship between other parameters (i.e. fiber tortuosity) and gravity of neuropathy.
Keywords: microscopy: confocal/tunneling • diabetes • cornea: clinical science