In vivo confocal microscopy study of climatic droplet keratopathy

Sir, Climatic droplet keratopathy (CDK) is a corneal degenerative disease characterized by its progressive opacity because of accumulation of globular deposits in Bowman’s layer (BL) and anterior stroma (AS), as well as abnormal corneal sensitivity.1, 2 We report herein for the first time the study of three patients each with different grades of CDK using in vivo confocal microscopy (iVCM), a technique that has allowed the measurement of normal and pathological corneal components.3, 4, 5 Table 1, Figures 1 and 2 summarize the corneal abnormalities found in these patients. Cochet-Bonnet aesthesiometry (CBA) demonstrated a decrease of the mechanical sensitivity of the cornea in eyes with grade II and III CDK. Grade I CDK was characterized by incipient changes in the BL and AS but normal sub-basal and stromal nerve plexus. Grade II CDK showed hyper-reflectivity and globular non-reflective deposits in the BL and AS. In grade III, the AS showed fibrosis with increment of diffused hyper-reflective deposits and large non-reflective deposits. Concomitant to these changes, there was an increased number of dendritic cells (DC) at the peripheral cornea and limbus, but their role in the progression of CDK needs further studies. No abnormalities were found in the rest of the stroma and endothelium. Although we were unable to study sub-epithelial nerves because they occupied the same area of the deposits in CDK, we found that the early changes in CDK did not affect the sub-basal and stromal nerves, but the progression of the disease lead to a significant density decrease of sub-basal nerves, and some structural changes in stromal nerves, such as uneven thickness and irregular configuration, that might be responsible for corneal hyposensitivity found in advanced stages of CDK. In a recent study, Patel et al5 showed that sub-basal nerve tortuosity but not mean total sub-basal nerve density varied with age in normal individuals. The loss of corneal sensation could not be attributed to the age of our patients as we have previously found in a case–control study that corneal sensation was related to CDK grades and not to the age of individuals.2 The authors declare no conflict of interest. This work was supported by CONICET PIP 112 200801 01455; SECYT-UNC 2009 (Argentina).