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
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.