The patient
Patient left profile
Unilateral Keratoconus induced by eye rubbing
Identity : Mr Q.H
First visit : 12/22/2015
Last Visit : 03/27/2018
Mr. Q.H is a 23-year-old male with no previous medical history other than atopy. He has no known history of keratoconus in the family . He has known allergy to pollen and dust mites, and complained of a progressive decrease in visual acuity greater in the left eye for several years.
His refraction at the first visit (12/22th/2015) was : Right Eye (RE) 20/20 with -2.25 (-0,5 x 140 °) and Left Eye (LE) 20/20 with -1 (-2 x 110°).
Clinical examination with the slit lamp suggested a slight irregular inferior corneal bulge in the left eye . We also found tarsal papillae on the conjonctival surface of the eylids (indicating chronic ocular allergy) in both eyes.
Corneal topography revealed the presence of a unilateral keratoconus in the left eye.
When asked first about his rubbing habits, the patient admitted to rubbing both eyes, particularly the left eye, because of itch. He rubbed his left eye frequently with the knuckles, and the right eye (less often) with the pulp of the index finger. also mentioned scratching his eyelids during allergy season, and having red eyes during that period. He sleeps on his left side.
At his subsequent visits, the patient verbalised remembering his grandfather chiding him for rubbing his eyes during childhood.
We explained to the patient that since vigorous eye 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 eye rubbing, and we treated his allergy at the same time.
Here are pictures of the patient rubbing his eyes and his profiles
PATIENT RIGHT PROFILE
PATIENT RUBBING HIS LEFT EYE: note the contact of the knuckles with the eyelids.
SLEEPING POSITION (HEAD ON HAND). This sleeping position is alternated during the night.Here are the Orbscan with SCORE Analyzer maps, Pentacam maps and Ocular Response Analyzer (ORA) results of the first visit .
RIGHT EYE ORBSCAN. This examination is quite unremarkable.
ORBSCAN LEFT EYE. The keratoconus is mostly inferior. Note the increased prolateness (negative asphericity) and toricity (astigmatism) of the anterior (top right) and posterior (top left) corneal surfaces (marked ridge- island pattern). On the curvature map (bottom left), irregular astigmatism is characterized by a marked inferior steepening . The thickness map (bottom right) shows central thinning with slight vertical displacement of the thinnest point.
RIGHT EYE SCORE. The SCORE is negative (no pattern of ectasia based on objective scoring)
LEFT EYE SCORE. The score is highly positive, mainly because of the high I-S (vertical) asymmetry in curvature.
RIGHT EYE PENTACAM. The Pentacam measurement of the right eye is unremarkable. 
LEFT EYE PENTACAM. Like the Orbscan map of the left eye, note the marked infero-temporal steepening with thinning. Many indices are "red" (indicative of keratoconus).
RIGHT EYE ORA. The ORA measurement of the right eye is unremarkable, despite a slight reduction in the height of the peaks.
ORA LEFT EYE. The applanation peaks are low and more irregular than the right eye.Difference maps were performed at each subsequent visit. No evolution was observed between the first and last visits. The keratoconus is stable, more than 2 years after the patient definitively stopped rubbing his eyes .
RIGHT EYE ORBSCAN (2nd VISIT)
RIGHT EYE PENTACAM (2nd VISIT)
RIGHT EYE ORBSCAN (3rd VISIT)
RIGHT EYE PENTACAM (3rd VISIT)
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE (between 2nd and 3rd VISITS). The third column (subtraction map) is green (no difference). The cornea is unchanged.
RIGHT EYE ORBSCAN (4th VISIT)
RIGHT EYE PENTACAM (4th VISIT)
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE (between 3rd and 4th VISITS). There is no change.
LEFT EYE ORBSCAN (2nd VISIT)
LEFT EYE PENTACAM (2nd VISIT)
LEFT EYE ORBSCAN (3rd VISIT)
LEFT EYE PENTACAM (3rd VISIT)
PENTACAM DIFFERENTIAL MAPS : LEFT EYE (between 2nd and 3rd VISITS). The third column shows the absence of significant change between the 2nd and 3rd examinations: this demonstrates stability of the keratoconus.
LEFT EYE ORBSCAN (4th VISIT)
LEFT EYE PENTACAM (4th VISIT)
PENTACAM DIFFERENTIAL MAPS : LEFT EYE (between 3rd and 4th VISITS). There is no progression.
RIGHT EYE ORBSCAN (5th VISIT)
LEFT EYE ORBSCAN (5th VISIT)
RIGHT EYE PENTACAM (5th VISIT)
LEFT EYE PENTACAM (5th VISIT)
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE 
PENTACAM DIFFERENTIAL MAPS : LEFT EYE This case reveals a very common cause of eye rubbing (and therefore keratoconus) : Allergic conjunctivitis, a condition where the eyes are red, swollen, blurred, watery and severely itchy, due to a sensitivity to allergens that are known or unknown. Quality of life can be poor for these patients as there is a constant need to rub their eyes to alleviate the symptoms, but rubbing usually aggravates the symptoms, resulting in a vicious circle of ocular discomfort. The first-line therapeutic solution for allergic conjunctivitis includes topical antihistamines and mast cell stabilisers, but many patients subsequently require topical or even oral corticosteroids, and other topical immunomodulators (e.g. cyclosporine A or tacrolimus). It is important to treat the underlying allergic conjunctivitis to stop the patient’s urge to rub the eyes and prevent the onset or progression of keratoconus.
The asymmetry of keratoconus development in this case may be related by the habit of preferentially rubbing the left eye with the knuckles, whereas the right eye was rubbed less often and with the pulp of the index finger.
The patient should be made to understand that despite the pleasurable sensations evoked by eye rubbing, the habit is in fact damaging to the cornea, and can result in irreparable damage. Chronic intense eye rubbing can also induce laxity of the eyelid. This loss of elasticity of the eyelid is a less serious problem, but it can compromise the ocular surface and exacerbate the ocular pruritus.
This case is very informative and demonstrative of the direct causal effect of eye rubbing in the genesis of keratoconus. Allergy is a classic risk factor for the disease, but this association exists probably because allergic patients tend to rub their itchy eyes more often and more vigorously than non-allergic patients.
The cessation of eye rubbing and proper allergy therapy are the keys in the prevention of the onset and/or evolution of keratoconus.
