The word keratoconus originates from the Greek word “kéras” meaning cornea and the Latin word “cōnus” meaning cone. This denomination is purely descriptive however, and does not suggest any mechanism to account for the corneal deformation which remains the hallmark of the disease. The progressive structural deformation of the corneal shape leads to refractive instability and reduction in the optical quality of the keratoconic eye. The exact molecular or tissue abnormalities in keratoconus are still unknown.
Eye rubbing is a common activity occurs at different times of the day: most regularly upon waking, before sleep, during extended computer work, and throughout the day in response to ocular itch and irritation, fatigue or emotional stress (1,2). It is usually benign but when performed too vigorously, too frequently, or over extended periods, rubbing becomes pathological and can be harmful for the cornea. Prolonged and repetitive forceful knuckle rubbing is often seen in keratoconus.
In this paper, I wish to defend a new theory in which abnormal eye rubbing is not just a risk factor, but is the main and necessary causative factor of keratoconus (3). In this postulate therefore, the absence of rubbing would prevent keratoconus from occurring and this conjecture may be condensed as: “no rub, no cone”.
In mathematics, a conjecture is a proposition which is consistent with known data. It has neither been verified nor shown to be false. Whilst formal proof that eye rubbing is the indispensable causative factor for keratoconus may be difficult, « no rub, no cone » represents a valid conjecture for elucidating the mystery of the pathophysiology of keratoconus, therefore offering potential benefits to the management of what is considered the most frequent corneal “dystrophy”.
The blunt statement “that eye rubbing is a chronic mechanical injury necessary to trigger and accelerate the corneal deformation observed in keratoconic eyes” defies the widely adopted theory that keratoconus is primarily a corneal dystrophy. However, it is entirely possible that keratoconus may truly be a primary mechanical disease and in fact, I would submit that this mechanical theory provides a better explanatory framework for what is currently known about keratoconus (KC). This theory does not contradict previous clinical or experimental findings about KC, all of which can be interpreted in light of this proposed mechanism. Rather, it is a synthetic approach that incorporates the results of previous genetic and biochemical approaches for understanding the pathophysiology of keratoconus. In fact, the mechanical disease proposition would appear more compatible with explaining the variability of keratoconus expression between patients, between eyes and the predominance of sporadic cases.
Beyond academic debate, the “no rub, no cone” conjecture suggests that there is a possibility of stopping the progression of existing keratoconus by cessation of eye rubbing. Even more importantly, if the mechanical injury caused by chronic eye rubbing really is a necessary ingredient in the recipe of the keratoconus disease, surely its suppression would make it possible to even eradicate it. As such, it should raise significant interest among the medical and ophthalmic community.
A conjecture is considered proven only when it has been shown that it is logically impossible for it to be false. Whilst mathematicians would seek robust demonstrative proof to make it a theorem, in contrast, new theories in medicine can be supported by conjectural models relying on tangible evidence. In what follows, I will show why the “no rub, no cone” conjecture may be proven correct by existing logical data and evidence. The line of arguments developed here will hopefully receive enough consideration to be accepted as a viable theory and, if proven true, lead to new guidelines for managing and preventing keratoconus.Find out more