Abstract
Purpose: :
To report the corneal nerve morphology changes by in vivo confocal microscopy in both eyes of dry eye patients with asymmetric ocular surface involvement.
Methods: :
In a cross-sectional, prospective study, we used Cochet-Bonnet esthesiometer (Luneau Ophthalmologia) and a CS4 confocal microscope (Nidek Technologies) in both eyes of patients with severe dry eye syndrome who showed a significant asymmetry (≥ 2) in corneal fluorescein staining (Oxford scale) between the two eyes. Corneal sensation and confocal images of the subbasal nerve plexus were obtained centrally. Confocal images were analyzed in regards to corneal nerve morphology, including the total number of nerves, number of main nerve trunks, total length of nerves per image (nerve fiber density), branching pattern, and tortuosity.
Results: :
A total of 7 patients comprised of 3 patients with ocular graft-versus-host disease (GVHD) and 4 patients with Sjogren syndrome were recruited. Nerve fiber densities in eyes with higher degrees of ocular surface changes were significantly lower than the contralateral eyes with less involvement. Interestingly, five out of seven patients were more symptomatic in the eye with less ocular surface involvement. Corneal sensation did not show strong correlation with the severity of ocular surface changes.
Conclusions: :
The significant decrease in nerve fiber density of subbasal nerve plexus correlates with increased severity of corneal surface alteration in dry eye syndrome. The morphological changes in sub-basal corneal nerves revealed by in vivo confocal microscopy may provide some possible explanation for the lack of strong association between signs and symptoms in dry eye patients.
Keywords: cornea: tears/tear film/dry eye • cornea: clinical science • innervation: sensation