It’s clear that there is a link between eye rubbing and keratoconus. Eye rubbing can alter the strength of the cornea, which can cause keratoconus to progress, but there is some controversy regarding whether it causes keratoconus. To answer the latter question, the first step in trying to understand whether eye rubbing can cause keratoconus, is to first understand much force eye rubbing applies to your eyes – something that was previously unknown.
ELZA’s surgeons, researchers, and its colleagues decided to measure the mechanical forces applied to the eyelids when people rub their eyes, and the results of their investigation have been published in the journal, BMC Ophthalmology (1).
People rub their eyes in three different ways: with their fingertips, their knuckles, and with their fingernails. We found that of the 57 patients we examined, 51% were fingertip rubbers, 44% were knuckle rubbers, and the remaining 6% were fingernail rubbers. When we measured how much force was applied during rubbing, we found that, on average, knuckle rubbing applied significantly more force to the eyelids (9.6 N) than fingertip rubbing (4.3 N) or fingernail rubbing (2.6 N). In other words, knuckle-rubbing applies 2.2 and 3.7 times more force to the eyelid (and through that, the cornea underneath) than fingertip or fingernail rubbing.
Eye rubbing with fingertips
Eye rubbing with knuckles
The reason why we wished to obtain this knowledge was to incorporate it into our ongoing research in building an experimental rubbing model, which aims to investigate the effect of repeated rubbing of the eye on the strength of the cornea, and whether there is any correlation between the ways people rub their eyes, the force applied, and how many times a cornea needs to be rubbed before the cornea becomes weakened. This experimental work will be the first step in answering the question, once and for all, if eye rubbing and keratoconus development – not just progression – are linked.
To read the paper, click on the image below:
- Hafezi F, Hafezi NL, Pajic B, et al. Assessment of the mechanical forces applied during eye rubbing. BMC Ophthalmol. 2020;20(1):301.