Eye rubbing, pillow contact, and corneal endothelial cell density

While eye rubbing and eye-pillow contact increase the risk of keratoconus, their association with corneal endothelial cell density (ECD) and central corneal thickness (CCT) remains unclear. The goal of this study was to assess the association between these behaviors and corneal ECD and CCT.

This was a cross-sectional study including 296 otherwise healthy eyes of 162 nondiabetic patients with cataract who underwent non-contact specular microscopy prior to cataract surgery. All patients completed a detailed questionnaire regarding their eye rubbing habits and eye contact with the pillow during sleep. Comparisons of means, correlation tests and one-way ANCOVA test were performed to analyze the data.

Eye rubbing was associated with a significantly lower ECD. Eye rubbers had a mean ECD of 2470±275 cells/mm² compared to 2611±313 cells/mm² in non-eye rubbers (P=0.000), representing a 5.4% lower ECD in eye rubbers. This remained significant after controlling for age (P=0.000). No significant difference in CCT was noted between eye rubbers and non-eye rubbers (P=0.951). No significant differences in ECD (P=0.249) or CCT (P=0.084) were found between eyes with and without eye-pillow contact. A small significant positive correlation was found between ECD and CCT (P=0.008). The endothelial cell loss rate was 0.28% per year of age.

The lower ECD found in eye rubbers appears to be less clinically significant than changes caused by mechanical stress to the corneal stroma (as seen in keratoconus). The lower ECD in eye rubbers can be explained by elevated intraocular pressure and direct mechanical stress caused by eye rubbing. Further prospective research is needed to analyze in greater detail the association between corneal mechanical stress and corneal endothelial health. In addition, this study is the first to report epidemiological data on ECD and CCT in a Lebanese sample.

Eye rubbing is associated with a lower corneal endothelial cell density.