Clinical, functional and structural studies of humans and merino sheeps corneas from two different regions of Argentina

Abstract

The purpose of our work was to study and compare the cornea and tear film of people and sheep inhabiting in a region of Argentinean Patagonia (PATG), and in a geographically and climatically different region in the Argentinean Pampa (CAPT). Methods: Using cross sectional study, corneal examinations were performed in people and Merino sheep inhabiting PATG and CAPT regions, respectively. All people completed a questionnaire related to work activity, diet, and the use of hats or sunglasses during their life. Eyes from all participants were examined with a portable handheld slitlamp biomicroscope (BM) to evaluate corneal appearance, epithelium integrity, and transparency. Later on, in a subgroup of participants we studied eyeblinking frequency (EBF), ocular surface staining (FS), breakup time (BUT), Schirmer Tear Test (STT), corneal structure using confocal laser scanning microscopy (CLSM) and light microscopy (LM), and concentrations of serum ascorbate (sAA). Results: BM studies revealed numerous cases of Climatic Droplets Keratopathy (CDK) only in people inhabiting the PATG region. CLSM studies confirmed typical punctiform deposits at the Bowman´s layer in CDK patients living in that region. CLSM images from sheep did not show any abnormalities at the Bowman´s layer but exhibited small hyper reflective dots at the epithelium only in animals pasturing in the PATG region. FS and EBF mean values were significant higher in sheep grazing in the PATG region (p <0.05). No differences were found in surface eye tests when people from both regions were analyzed. Low sAA levels were found only in CDK people living in PATG region. Conclusions: CDK is a multi-factorial disease not only associated to harsh climate. We provide data that low sAA levels can play a role in its genesis in Patagonia patients'... Sheep pasturing in this region with a high prevalence of CDK have high concentration of sAA and did not present any sub epithelial corneal abnormalities.