Mr. N.N is a 20-year-old male with no previous medical history or any known family history of keratoconus. He has known allergy to dust mites and pollen and has atopic eczema and asthma. The patient complained of a progressive decrease in visual acuity in the right eye.
His refraction at the first visit (07/26th/2016) was : Right Eye (RE) 20/20 with -1 (-5.25 x 50 °) and Left Eye (LE) 20/20 with -0.5 (-0,25 x 180 °).
Clinical examination with the slit lamp suggested an irregular inferior corneal bulge with a Fleischer ring (Fleischer rings are pigmented rings in the peripheral cornea, resulting from iron deposition in basal epithelial cells, in the form of hemosiderin) and Vogt’s striae (vertical fine, whitish lines in the deep/posterior stroma and Descemet’s membrane commonly found in patients with keratoconus) in the right eye, with tarsal papillae (indicating chronic ocular allergy) in both eyes. There is also coexistent ocular rosacea with blepharitis (common inflammation of the eyelid margins caused by abnormal secretion of Meibomian glands).
Corneal topography revealed the presence of a unilateral keratoconus in the right eye.
He was advised to undergo fairly urgent corneal collagen cross-linking in another institution, and came to us for more information and a second opinion.
When asked about the possibility of an eye rubbing habit, the patient admitted to be rubbing his eyes (with the knuckles) frequently every day, especially when working in front of the computer. His mother, who was present at the consultation, confirmed that she often witnessed her son rubbing his eyes vigorously. Then patient is right-handed and sleeps on his right side.
We explained to him that the onset and progression of keratoconus was very likely linked to eye rubbing in his case. We strongly advised him to stop rubbing his eyes and advised him to pay attention to this habit, not only when he is at the computer (where people’s minds are usually focused on other thoughts) but also in the mornings, under the shower, at night or at bedtime, etc. We also treated his allergy and ocular rosacea.
Here are pictures of the patient rubbing his eyes and his corneal profiles
In this case we find many triggers for eye rubbing like allergy, extended work on the computer and a particular sleeping position (on the side, with ocular compression at night). The asymmetry of the keratoconus development may be related to the sleeping position (right side) and the coexistent habit of preferentially rubbing the right eye. We also believe that the dominant hand may have a role in asymmetry because the force applied by the dominant hand is probably higher than that of the non-dominant hand. Eye rubbing with the dominant hand may incite more local irritation as it often contains more allergens (since the dominant hand is used more than the non-dominant one). Just as excessive ligament extension can cause a sprained ankle, chronic eye rubbing can cause the corneal collagen fibers to lose part of their biomechanical resistance, resulting in macroscopically obvious structural deformation. This biomechanical mechanism could also better explain the frequent disparity in the degree of affliction between the right and left eyes (patients frequently rub one eye more often and more vigorously than the other) and the focal nature of keratoconus, which has been recently evidenced.
This case is very informative and demonstrative of the direct causal effect of eye rubbing in the pathogenesis of keratoconus. Allergy is a classic risk factor for the disease, but this association exists probably because allergic patients rub their itchy eyes more often and more vigorously than their non-allergic counterparts.
Thus, it is mandatory to reduce the incidence and progression of keratoconus by increasing the awareness of patients on the potential dangers of chronic and vigorous eye rubbing, and encouraging them to refrain from it.