Abstract
Purpose :
Nerve fibres and inflammatory cells in the corneal sub-basal nerve plexus have been well characterised in both ocular disease and peripheral neuropathy using in-vivo corneal confocal microscopy (IVCM). Other recently described features, globular cells (GC) and microneuromas (enlarged nerve terminal sprouts) have been reported to have a strong association with certain diseases, however, little is known about these features in healthy individuals, and hence, their future diagnostic utility. This study, therefore, set out to establish the profile of these features in a healthy population.
Methods :
IVCM images from 119 healthy participants (60 females, 59 males), aged 17 to 80 years (mean: 48 ± 16 years) from the combined control cohorts of two different studies were analysed. Five to eight images from the central cornea and inferior whorl (IW) were analysed for number of microneuromas, globular and dendritic (mature and immature) cell densities (DCD), corneal nerve fibre density (CNFD), branch density (CNBD), fibre length (CNFL), and total branch density (CTBD). Associations between and within the nerve and inflammatory features and age and gender were determined using appropriate non-parametric statistics.
Results :
Microneuromas and GCs were present in 35 and 31% of individuals respectively. The number of microneuromas at central cornea and IW were inversely associated with age (rho=-0.203, p=0.028; rho=-0.195, p=0.034), and mature and immature DCD both at central (rho=-0.272, p=0.003; rho=-0.360, p<0.001) and IW (rho=-0.201, p=0.028; rho=-0.287, p=0.002), and directly associated with CNFD (rho=0.269, p=0.003). Males had higher number of IW microneuromas than females (0.4 ± 0.8, vs 0.1 ± 0.4, p=0.008). GC density or presence had no association with age, gender or any other features. Mature and immature DCD were strongly associated, both in the centre and IW. Immature DCD was inversely associated with CNFD. Age was inversely associated with CNFD, IWCNFD, IWCNBD and IWCNFL.
Conclusions :
Despite their described association with ocular conditions, such as neuropathic ocular pain, microneuromas were relatively common in this healthy population, as were GCs. Further work is needed to characterise these features, and explore their development in healthy populations, particularly in understanding their relationship with the immune system.
This is a 2020 ARVO Annual Meeting abstract.