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

M. Tavakoli, P. Kallinikos, A. Iqbal, A. Herbert, H. Fadavi, N. Efron, A. J M Boulton, Rayaz Malik

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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 24months 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±3.8number/mm 2, P=0.001), nerve branch density (6.9±1.5 vs. 35.6±6.7number/mm 2, P<0.0001), nerve fibre length (8.3±0.9 vs. 13.5±0.8mm/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±2mmol/mol, P=0.08), total cholesterol (4.9±0.2 to 4.2±0.2mmol/l, P=0.01), systolic blood pressure (145.8±4.9 to 135.9±3.7mmHg, P=0.09) and diastolic blood pressure (77.8±2.7 to70.8±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.

Original languageEnglish
Pages (from-to)1261-1267
Number of pages7
JournalDiabetic Medicine
Volume28
Issue number10
DOIs
Publication statusPublished - Oct 2011
Externally publishedYes

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Keywords

  • Corneal confocal microscopy
  • Corneal nerves
  • Diabetic neuropathy
  • Risk factors

ASJC Scopus subject areas

  • Endocrinology
  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

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