Ms. T.E is a 22-year-old female medical student with no previous medical history, or any known history of keratoconus in her family of 6 siblings. She has no known allergies.
She complained of a progressive decrease in visual acuity in the right eye over a year.
Her refraction was : RE 20/40 with -1 (-5 x 15 °) and LE 20/20 with -3.50 (-0.5 x 10 °).
Clinical examination with the slit lamp revealed a discrete Fleischer ring and a thin slightly bulging cornea in the right eye. Examination of the left eye was unremarkable.
Corneal topography revealed unilateral keratoconus in the right eye. The left eye showed fruste forme keratoconus.
When asked about a possible eye rubbing habit, the patient was initially hesitant. However, her father, who was present during the consultation informed us that she often rubbed her eyes, especially the right one! She eventually admitted to rubbing her right eye at work and after taking a shower.
This patient is right-handed and she prefers sleeping on the right side.
We explained that unilateral (or predominant) right eye rubbing had caused the cornea to be warped and deformed, and that it was crucial for her to stop rubbing that eye. The fact that she was almost constantly sleeping on the right side may have caused chronic local irritation, itch and may explain the preferential rubbing on that side. We advised her to change her sleeping position, and to pay attention to possible right eye rubbing episodes in the mornings and after showering.
We fitted her with rigid gas permeable contact lenses and she wears swimming goggles in the shower to avoid contact irritation with water and therefore the need to rub her eyes.
This case represents another striking example of a unilateral keratoconus associated with unilateral eye rubbing with forme fruste keratoconus in the contralateral eye. This reinforces the hypothesis that eye rubbing, which precedes the onset of keratoconus, is the root cause of it.
This predominant rubbing of the right eye is probably linked to the sleeping habit (preferential sleeping on the right side, causing contact irritation of the right eye with allergens from the pillow and bed linen).
It should be noted that the ORA charts are almost identical in both eyes despite the unilateral keratoconus, which imply that both corneas have similar biomechanics. This suggests that, despite a similar corneal fragility, the asymmetry is mainly explained by her habits of ocular friction and sleeping side.