Morphometric stability of the corneal subbasal nerve plexus in healthy individuals: a 3-year longitudinal study using corneal confocal microscopy.
OBJECTIVE
We examined the age-dependent alterations and longitudinal course of subbasal nerve plexus (SNP) morphology in healthy individuals.


METHODS
Laser-scanning corneal confocal microscopy, ocular screening, and health and metabolic assessment were performed on 64 healthy participants at baseline and at 12-month intervals for 3 years. At each annual visit, eight central corneal images of the SNP were selected and analyzed using a fully-automated analysis system to quantify corneal nerve fiber length (CNFL). Two linear mixed model approaches were fitted to examine the relationship between age and CNFL, and the longitudinal changes of CNFL over three years.


RESULTS
At baseline, mean age was 51.9 ± 14.7 years. The cohort was sex balanced (χ(2) = 0.56, P = 0.45). Age (t = 1.6, P = 0.12) and CNFL (t = -0.50, P = 0.62) did not differ between sexes. A total of 52 participants completed the 36-month visit and 49 participants completed all visits. Age had a significant effect on CNFL (F[1,33] = 5.67, P = 0.02) with a linear decrease of 0.05 mm/mm(2) in CNFL per one year increase in age. No significant change in CNFL was observed over the 36-month period (F[1,55] = 0.69, P = 0.41).


CONCLUSIONS
The CNFL showed a stable course over a 36-month period in healthy individuals, although there was a slight linear reduction in CNFL with age. The findings of this study have implications for understanding the time-course of the effect of pathology and surgical or therapeutic interventions on the morphology of the SNP, and serves to confirm the suitability of CNFL as a screening/monitoring marker for peripheral neuropathies.
Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia.
Cirous
C
Dehghani
Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia.
Nicola
N
Pritchard
Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia.
Katie
K
Edwards
Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia.
Dimitrios
D
Vagenas
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Woolloongabba, Australia School of Medicine, University of Queensland, St. Lucia, Australia.
Anthony W
AW
Russell
Center for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, Manchester, United Kingdom.
Rayaz A
RA
Malik
Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia.
Nathan
N
Efron
D003315:Cornea / Q000294:innervation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods*; D008875:Middle Aged; D009412:Nerve Fibers / Q000648:ultrastructure; D009882:Ophthalmic Nerve / Q000166:cytology*; D012372:ROC Curve; D012016:Reference Values; D013997:Time Factors
age; corneal confocal microscopy; natural history; subbasal nerve plexus