The patient
Patient right profile
Unilateral Keratoconus induced by eye rubbing
Identity : Mr N.N
First visit : 07/26/2016
Last Visit : 05/09/2017
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
PATIENT RIGHT PROFILE
PATIENT LEFT PROFILE
PATIENT RUBBING HIS RIGHT EYE. Note the contact of the hard knuckles on the eyelids. When asked to demonstrate how they rub their eyes, most patients with unilateral keratoconus will rub the affected eye, and not the "normal" one.
PATIENT SHOWING HIS SLEEPING POSITION (RIGHT SIDE). Many patients with unilateral keratoconus sleep on the side or stomach, with the side of the head touching the pillow being the same as the laterality of the eye with the more severe (or unilateral) keratoconus. Here are the Orbscan quadmaps with SCORE Analyzer , OPDscan maps (topography and aberrometry), Pentacam maps and Ocular Response Analyzer (ORA) results of the first visit .
RIGHT EYE ORBSCAN. Note central keratoconus with asymmetry, irregularity and increased prolateness. There is marked oblique astigmatism. The cornea is thinned centrally.
From the Orbscan data, this software (based on automated linear discriminant analysis for keratoconus diagnosis) computes a positive value, confirming the presence of keratoconus.
RIGHT EYE PENTACAM (1st VISIT)
RIGHT EYE ORA. Note the reduced height of the applanation peaks, and the reduced CRF (corneal resistance factor) value.
OPD RIGHT EYE. The combined topographic and aberrometric examination reveals some increased higher order aberrations (coma, negative spherical aberration and trefoil). These aberrations cannot be corrected by spectacles. 
LEFT EYE ORBSCAN. Note presence of a normal corneal pattern , with mild irregular superior astigmatism. This contrasts with the topography pattern in the other eye.
From the Orbscan data, this software (based on automated linear discriminant analysis for keratoconus diagnosis) computes a negative value, indicating the absence of keratoconus.
LEFT EYE PENTACAM (1st VISIT)
LEFT EYE ORA. Note the reduced height of the applanation peaks, and the reduced CRF (corneal resistance factor) value, but this is higher than that in the right eye.
OPD LEFT EYE. The combined topographic and aberrometric examination is unremarkable.Difference maps were performed at each subsequent visit. No evolution was observed between the first and last visits. The keratoconus is stable, more than 8 months after the patient definitively stopped rubbing his eyes .
RIGHT EYE ORBSCAN (2nd VISIT)
RIGHT EYE PENTACAM (2nd VISIT)
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE (between 1st and 2nd VISITS)
RIGHT EYE ORBSCAN (3rd VISIT)
RIGHT EYE PENTACAM (3rd VISIT)
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE (between 2nd and 3rd VISITS). The difference map demonstrates the perfect stability of the corneal deformation (no keratoconus progression).
ORBSCAN DIFFERENTIAL MAPS : RIGHT EYE (between 2nd and 3rd VISITS). The changes are not significant (their low amplitude is related to "background noise"). Studies have shown that for advanced keratoconus, the repeatability of the instrument is lower. Changes below 1.75D are considered statistically insignificant.
LEFT EYE ORBSCAN (2nd VISIT)
LEFT EYE PENTACAM (2nd VISIT)
PENTACAM DIFFERENTIAL MAPS : LEFT EYE (between 1st and 2nd VISITS)
LEFT EYE ORBSCAN (3rd VISIT)
LEFT EYE PENTACAM (3rd VISIT)
PENTACAM DIFFERENTIAL MAPS : LEFT EYE (between 2nd and 3rd VISITS). The difference map between the 2nd and 3rd examinations reveals no significant change.
ORBSCAN DIFFERENTIAL MAPS : LEFT EYE (between 2nd and 3rd VISITS). The blue color would suggest that the cornea has flattened over time! (This is quite unexpected in this context). However, the magnitude of the changes is insignificant, as it is affected by the repeatability of topographic examinations. (Successive examinations on the same eye would not be exactly the same, due to the variability inherent to the measurement of a biological system, which can move and be oriented differently between two successive examinations).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.
