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. 2011 Oct;28(10):1261-7.
doi: 10.1111/j.1464-5491.2011.03372.x.

Corneal confocal microscopy detects improvement in corneal nerve morphology with an improvement in risk factors for diabetic neuropathy

M Tavakoli  1 , P Kallinikos, A Iqbal, A Herbert, H Fadavi, N Efron, A J M Boulton, R A Malik
Affiliations

Corneal confocal microscopy detects improvement in corneal nerve morphology with an improvement in risk factors for diabetic neuropathy

M Tavakoli et al. Diabet Med. 2011 Oct.

Abstract

Aim: We have assessed whether corneal confocal microscopy can be used to detect alterations in nerve morphology following an improvement in risk factors associated with diabetic neuropathy.

Methods: Twenty-five patients with diabetes with mild to moderate neuropathy and 18 control subjects underwent corneal confocal microscopy to quantify corneal nerve fibre (density, branch density, length and tortuosity) at baseline and after 24 months from first visit. This was not planned as an intervention trial and was simply an observational follow-up.

Results: At baseline, nerve fibre density (18.8 ± 2.1 vs. 46.0 ± 3.8 number/mm(2), P = 0.001), nerve branch density (6.9 ± 1.5 vs. 35.6 ± 6.7 number/mm(2), P < 0.0001), nerve fibre length (8.3 ± 0.9 vs. 13.5 ± 0.8 mm/mm(2), P < 0.0001) and nerve fibre tortuosity (19.8 ± 1.6 vs. 22.7 ± 2.2, P < 0.05) were significantly lower in patients with diabetes than in control subjects. At follow-up, glycaemic control (HbA(1c) 64 ± 3 to 58 ± 2 mmol/mol, P = 0.08), total cholesterol (4.9 ± 0.2 to 4.2 ± 0.2 mmol/l, P = 0.01), systolic blood pressure (145.8 ± 4.9 to 135.9 ± 3.7 mmHg, P = 0.09) and diastolic blood pressure (77.8 ± 2.7 to 70.8 ± 2.5, P = 0.03) improved. Nerve fibre density (24.1 ± 2.0, P = 0.05), nerve branch density (11.1 ± 1.3, P < 0.01) and nerve fibre tortuosity (22.6 ± 1.5, P = 0.05) increased significantly, with no change in nerve fibre length (8.4 ± 0.5). Improvement in nerve fibre density correlated significantly with the improvement in HbA(1c) (r = -0.51, P = 0.008). Via four multifactorial regressions, this confirms the negative association between HbA(1c) and nerve fibre density (P = 0.02).

Conclusions: This study shows that corneal confocal microscopy may be employed in longitudinal studies to assess progression of human diabetic neuropathy and also supports the hypothesis that improvements in risk factors for diabetic neuropathy, in particular HbA(1c) , may lead to morphological repair of nerve fibres.

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Figures

Figure 1
Figure 1
Corneal confocal microscopy images of Bowman’s layer from a diabetic patient at (a) baseline and (b) follow-up.
Figure 2
Figure 2
Change in HbA1c (P = 0.08), cholesterol (P = 0.01), systolic (P = 0.09) and diastolic (P = 0.03) blood pressure from baseline to follow-up.
Figure 3
Figure 3
Change in corneal confocal microscopy corneal nerve morphology from baseline to follow-up.
Figure 3
Figure 3
Change in corneal confocal microscopy corneal nerve morphology from baseline to follow-up.
Figure 3
Figure 3
Change in corneal confocal microscopy corneal nerve morphology from baseline to follow-up.
Figure 3
Figure 3
Change in corneal confocal microscopy corneal nerve morphology from baseline to follow-up.
Figure 4
Figure 4
Correlation between change in nerve fibre density with change in HbA1c (r = −0.52, P = 0.008).
See this image and copyright information in PMC

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