Patient right profile
Case #95
The patient
Bilateral Keratoconus induced by eye rubbing
Identity : Mr M.N
First visit : 05/22/2018
Last Visit : 09/19/2018
20
Age (years)4
Follow-up (months)Mr. M.N is a 20-year-old male. He has asthma and allergy to dust mites and had to undergo desensitization treatment for his allergies in the past. He has a twin brother (monozygotic) who does not have keratoconus and they are currently living together in the same house. Mr M.N presented to us complaining of a progressive decrease in visual acuity greater in the right eye than the left.
His refraction at the first visit at the Rothschild Foundation (on 05/22th/2018) was : Right Eye (RE) 20/80 with -5.75 (-3.5 x 35 °) and Left Eye (LE) 20/32 with -3.5 (-1.5 x 145 °).
Clinical examination with the slit lamp revealed a thin cornea with Vogt’s striae (fine whitish lines in the posterior stroma) and Fleischer rings (Fleischer rings are pigmented rings in the peripheral cornea, resulting from iron deposition in basal epithelial cells, in the form of hemosiderin), in both eyes.
Corneal topography performed at our institution showed the presence of bilateral keratoconus, more pronounced in the right eye.
When first asked about eye rubbing, the patient declared that it did not occur to him that he would particularly rub his eyes, although he would sometimes do it mechanically more as a reflex action because his eyes felt itchy. We asked the patient to pay more attention to possible conscious rubbing episodes, and gave him an appointment for a review visit one month later.
During the second visit, the patient acknowledged that he had come to realize that he was rubbing his eyes way more than he had thought, in particular at the office in front of the computer screen to relieve ocular fatigue and itch or at home after removal of his rigid contact lenses.
He is left handed and he used to rub his both eyes, and preferably his right eye with his right hand. He would use his knuckles to rub both eyes, a gesture that he would perform many times a day.
His twin brother does not rub his eyes.
The patient sleeps on his right side, with the head buried in the pillow (pillow hugging).
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 him to stop rubbing his eyes, and to change his unhealthy sleeping position. We also treated his ocular allergy with anti-histamine eye drops.
Here are pictures of the patient rubbing his eyes and his profiles
PATIENT RIGHT PROFILE
PATIENT LEFT PROFILE
PATIENT RUBBING HIS EYES WITH KNUCKLES
PATIENT SLEEP POSITION (ON THE RIGHT SIDE WITH THE HEAD IN THE PILLOW)
THE TWO TWIN BROTHERSHere are the Orbscan quadmaps, Pentcam maps, OPD scans, Ocular Response Analyzer (ORA) results, and Corneal OCT epithelial maps of the first visit
RIGHT EYE ORBSCAN (1st VISIT). The distortion of the right cornea is obvious, and accompanied by central thinning and increased negative asphericity of the anterior and posterior corneal surface.
LEFT EYE ORBSCAN (1st VISIT). The corneal deformation has a gross pattern similar to that of the right eye, but is less pronounced.
RIGHT EYE PENTACAM (1st VISIT). The asymmetry and central thinning parallels the Orbscan map features.
LEFT EYE PENTACAM (1st VISIT). The asymmetry and central thinning parallels the Orbscan map features.
RIGHT EYE OPD. The wavefront analysis reveals the presence of increased amounts of negative spherical aberration and vertical coma.
LEFT EYE OPD. The wavefront analysis reveals the presence of increased amounts of negative spherical aberration and vertical coma.
RIGHT EYE ORA (Ocular Response Analyzer) The height of the applanation peaks is reduced. This suggests an increased susceptibility to corneal deformation.
LEFT EYE ORA (Ocular Response Analyzer). The ORA measurement of the left eye is unremarkable, despite a slight reduction in the height of the peaks.
RIGHT EYE : EPITHELIAL MAPPING The epithelium is thicker in the paracentral area
LEFT EYE : EPITHELIAL MAPPING The epithelium is thicker in the paracentral areaDifference maps were performed at each subsequent visit. No evolution has been observed between the first and last visits. The keratoconus is stable, more than 4 months after the patient definitively stopped rubbing his eyes.
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE (between 1st and 2nd visits). The difference map (third column) and its related indices demonstrate the absence of evolution of the corneal deformation.
PENTACAM DIFFERENTIAL MAPS : LEFT EYE (between 1st and 2nd visits). The difference map (third column) and its related indices demonstrate the absence of evolution of the corneal deformation.
PENTACAM DIFFERENTIAL MAPS : RIGHT EYE (between 1st and 3rd visits). The difference map (third column) and its related indices demonstrate the absence of evolution of the corneal deformation.
PENTACAM DIFFERENTIAL MAPS : LEFT EYE (between 1st and 3rd visits). The difference map (third column) and its related indices demonstrate the absence of evolution of the corneal deformation.We have here monozygotic twin brothers with an identical genetic makeup, living in the same environment. One rubs his eyes incessantly, the other does not. The former has keratoconus, the other does not.
This case is an important example to support the mechanical (eye rubbing) theory of keratoconus genesis, and effectively debunks the current consensus that keratoconus is an inherited disease primarily caused by a biochemical abnormality, which could be transmitted genetically or occur sporadically. This however, does not imply that genes have no role in the pathogenesis of keratooconus and its progression. Genetics play a role by creating a susceptibility to corneal fragility and in the development of allergies, which cause ocular pruritus (itch), and induces the urge to rub the eyes. .
The key difference between these twin brothers is the eye rubbing habit and the resultant external force exerted on the cornea from the incessant eye rubbing. It is therefore appropriate to consider replacing the current genetic theory with that of a mechanical theory, which advocates that keratoconus is primarily a mechanical disease induced and perpetuated by chronic and vigorous eye rubbing.
The corneal dome can be likened to a shell whose equilibrium geometry depends on the difference between the intraocular pressure (exerted on its posterior surface) and the atmospheric pressure. Beyond a certain threshold, the mechanical stresses (compression and shear) conveyed by eye rubbing results in a biomechanical embrittlement, due to the rupture of the harmonious arrangement of collagen fibers, which causes an irreversible deformation of the cornea (This mechanism is analogous to the « buckling » in resistance of materials).
On this site, we wish to therefore convey the following message: that keratoconus would not appear or evolve without the action of an external mechanical force, which is conveyed by the hands (fingers, knuckles or nails) of patients who rub their eyes. Based on our experience with dozens of documented cases in this website, including this one, it appears that ocular friction (or repeated mechanical stress) is not the consequence of keratoconus or a mere risk factor, but most likely THE CAUSE of keratoconus.
The cessation of eye rubbing and treatment of allergies to curb eye rubbing are the best tools in the prevention of the genesis and/or evolution of keratoconus.
- Date 2 novembre 2018
- Tags Allergy, Asymmetric, Bilateral keratoconus, Childhood rubbing, Eye rubbing, Inferior keratoconus, Knuckles rubbing, Lens removal rubbing, Male, Pillow hugging, Rigid lens, Sleep position, Stabilization