To Rub Or Not To Rub: Is Hand Dominance Related To More Severe Keratoconus And Choroidal Thickness?

Keratoconus (KC) is characterized as a degenerative ectatic corneal disease. Established risk factors for KC include eyerubbing and atopy. Our research group has previously identified an association between keratoconus and elevated choroidal subfoveal thickness (CST), hinting at a potential inflammatory pathogenesis for this condition. A correlation of increased CST was also established with eyerubbing. These observations prompt inquiry into the potential correlation between the laterality of the dominant hand (HD) and the severity of the affected eye. Furthermore, an exploration of the symmetry of choroidal thickness augmentation between eyes is essential, as asymmetry may suggest distinct mechanisms underlying this thickness increase.

Single-center, cross-sectional study of 103 patients with Keratoconus followed in the Cornea and Anterior Segment Clinic of Centro Hospitalar e Universitário de São João.

In this study, we examined 206 eyes with keratoconus from a total of 103 individuals aged 16 to 30 years. Spectral-domain optical coherence tomography (OCT) with depth-enhanced imaging was utilized for choroidal thickness measurements at the central fovea and at 500 μm intervals along a horizontal section. Simultaneously, OCULUS Pentacam assessments were conducted during the same visit, capturing tomographic parameters (Kmax, Km, Pachymin, and D-index). The classification of KC was determined using the Pentacam HR Topographical Keratoconus Classification system. Patients were inquired about their HD and rubbing habits.

KC classification, as well as CST, does not appear to be related to the laterality of the HD (p=0.223 and p=0.77, respectively). The CST is not correlated with the degree of KC. There are statistically significant correlations between being an eyerubber and CST, and the frequency of eyerubbing (FE) and CST (ρ=0.246, p=0.002; r=0.230, p=0.004, respectively). The FE is not correlated with KC classification (r=0.072, p=0.379).

We found no association between the laterality of HD and the severity of KC. Despite that, our study revealed a significant correlation between the increase in CT and eyerubbing mechanisms. Interestingly, HD did not appear to influence CST between both sides. Consequently our findings suggest that the increased CST in KC may be attributed not solely to eyerubbing mechanisms but potentially to broader systemic inflammatory mechanisms. This aligns with prior research conducted by our group, providing valuable insights into the underlying mechanisms of KC pathogenesis.