Corneal in vivo Confocal Scanning Laser Microscopy in Patients With Vernal Keratoconjunctivitis

Abstract

Purpose: : To study the morphologic alterations of the cornea in active vernal keratoconjunctivitis (VKC) using confocal scanning laser microscopy compared to normal subjects.

Methods: : Twenty-four VKC patients (18 males, 6 females) and 15 normal subjects (10 males, 5 females) were included in this comparative study. All subjects underwent a full ophthalmological examination and skin prick test. ConfoScan CS4 (Nidek, Gamagori, Japan) images of the central cornea were obtained with a 40x non-contact lens and Z-ring device. The epithelial cell, endothelial cell and keratocyte densities of the central cornea, the characteristics of the sub-basal long nerve fibers and of the sub-basal nerve plexus were studied and compared to those of normal subjects.

Results: : Compared to normal subjects, VKC patients showed an increased diameter and reflectivity of the superficial epithelial cells (p<0.0001); increased density of the basal membrane (p<0.0001); higher reflectivity (p<0.005) and lower density of keratocytes (p<0.01), increased number of activated keratocytes (p<0.001) and increased number of inflammatory cells (p<0.01) in the anterior stroma; lower density (p<0.01) and number (p<0.05) of fibers and lower number of beadings in the sub-basal nerve plexus (p<0.0001); increased thickening (p<0.005), deflections (p<0.001) and bifurcation abnormalities (p<0.01) of stromal nerves. Furthermore, an increased number of cells in close proximity to the sub-basal and stromal nerve fibers was more frequently observed in VKC (83% of patients) compared to normal subjects (p<0.01).

Conclusions: : The corneal involvement in VKC, even if subclinical, is associated with significant alterations of the epithelium, as well as the sub-basal and stromal corneal nerves. This may be related to the changes in tear functions and the non-specific hyperreactivity of these patients. Confocal scanning laser microscopy is useful in the study of pathological in vivo corneal changes in VKC and might prove useful in the monitoring of topical treatments for ocular allergic diseases.

Keywords: microscopy: confocal/tunneling • cornea: epithelium • cornea: stroma and keratocytes