Mr. P.B is a 29-year-old male computer scientist with no previous medical history or any known history of keratoconus in the family. He complained of a progressive decrease in visual acuity in the left eye.
His refraction at the first visit (03/17th/2017) was : Right Eye (RE) 20/20 with -0.25 (-0.25 x 140 °) and Left Eye (LE) 20/40 with -1 (-2.5 x 45 °).
Clinical examination with the slit lamp revealed signs of keratoconus, with prominent corneal nerves in the left corneal stroma. We also discovered a discrete Fleischer ring in the left eye (Fleischer rings are pigmented rings in the peripheral cornea, resulting from iron deposition in basal epithelial cells, in the form of hemosiderin), and tarsal papillae (indicating chronic ocular allergy).
Corneal topography confirmed the presence of unilateral keratoconus in the left eye.
When asked at the first visit about the possibility of frequent eye rubbing, the patient admitted to rubbing his eyes with his knuckles when working in front of the computer. He rubbed the left eye in particular. The patient is right-handed and sleeps on the left side. He described using his right hand on the computer mouse and rubbing his left eye with the left hand.
During the second visit, he admitted to realizing that he was rubbing his eyes more frequently than he had thought, especially in the mornings on awaking and more frequently in front of the computer.
We explained to the patient that since vigorous rubbing had preceded the drop in visual acuity, this habit may have caused the cornea to deform in his case. We strongly advised this patient to stop rubbing his eyes. After being sensitised to the deleterious effects of eye rubbing, he managed to kick the habit, and instead moisturised the ocular surface with artificial tears when he felt the urge to rub. He also altered his sleeping position by sleeping on his back.
Here are pictures of the patient rubbing his eyes and his profiles
This case is intriguing and quite instructive about the causal effect of eye rubbing on the genesis of the corneal deformation called « keratoconus ». The asymmetry in the corneal deformation between the left and right eyes resides in the fact that the patient predominantly rubbed his left eye. Like many of the other cases described in this site, in occupations where one hand is used more than the other for work (computer analyst using the mouse, mechanic, engineer etc), this patient uses his free hand to rub his homolateral eye (the left one here). This patient also sleeps on the left side, and it is possible that chronic ocular compression by the pillow and contamination from the linen irritates the left eye further causing it to be itchy. Rubbing results in temporary relief, but aggravates the situation by adding extra germs and irritants to the ocular surface. It then triggers more rubbing, causing the cornea to deform progressively.
Most medical text books would attribute keratoconus to an unknown genetic factor. Genetics alone would not explain the unilateral occurrence of keraotconus in many cases, while eye rubbing does very well (unilateral rubbing causes unilateral keratoconus). Genetics however, may account for increased ocular sensitivity, atopy, and reduced corneal resistance to repeated trauma.
The cessation of rubbing in this case has arrested the progression of keratoconus.