Results of our online study

Cessation of Eye Rubbing to Halt Progression of Keratoconus: Two-year Follow-up

BACKGROUND

Keratoconus is a condition whose origin has long been unknown. Through our clinical interactions with thousands of keratoconus patients over the years, we strongly believe that the origin of keratoconus may no longer be an enigma, and that eye rubbing is the all-important causative factor for this disease.

Despite the cumulative evidence, it is difficult to formally prove this assertion. For one, it is not possible, due to ethical reasons, to conduct a prospective study where patients are asked to rub their eyes vigorously and repeatedly to determine if keratoconus could be induced. However, it is possible to take advantage of the large number of keratoconus patients seen and monitored at our Institution to study the impact of eye rubbing on not only the genesis of the disease but also on its progression. If our assumption that eye rubbing is responsible for the onset and evolution of the disease is correct, then the cessation of eye rubbing must, at least in the early and moderate forms, arrest the progression of keratoconus.

A novel and effective way of monitoring clinical cases and sharing their progress is to document them prospectively in an open fashion online.

This is what we have done on this website.

The idea of building this keratoconus and eye rubbing portal came about in late 2016. Since then, whenever a patient is newly diagnosed with keratoconus by our team of doctors, or when a patient with known keratoconus presents to us for a routine review, the collection of the necessary clinical data including relevant photos and video recordings for the study is initiated, and the information uploaded to this website.

This website now displays more than 100 cases of keratoconus. Each case is thoroughly analyzed, at inclusion and at subsequent visits. The statistics and percentages reported here will be updated over time, and this series of cases will constitute the core of a future publication in a peer-reviewed medical journal.

AIMS

The study aims to determine the following:

1/If there is a correlation between eye rubbing and keratoconus in terms of laterality, frequency and intensity.
2/If there is a correlation between sleeping position and keratoconus
3/If stabilization of keratoconus is achievable through the cessation of eye rubbing alone: this is the most important point.

METHODOLOGY

This prospective cohort study included consecutive patients, aged between 15 and 50 years and diagnosed with keratoconus at the Rothschild Foundation (Paris, France). Patients were instructed to stop rubbing their eyes indefinitely, on their first visit. We ensured that criterion was respected during the follow-up at 1, 3, 6, 12, 36, 48 and 60 months. The main outcomes measures were related to the visual performance (visual acuity), and more specifically to parameters altered in case of progressive corneal deformation. The measured curvature of the cornea is labeled « keratometry » and is variable over its total surface area.

  • The distance best corrected visual acuity (BCVA): This parameter indicates the level of sharpness of the retinal image, for an eye which is best spectacle-corrected. In keratoconus, the corneal deformation causes a reduction of the optical quality of the cornea. The best visual acuity that the human eye is capable of (without or with spectacles) is 20/10. If the corneal deformation exceeds a certain level, the amount of irregular astigmatism (which cannot be corrected by spectacles) can cause a loss of some lines of best visual corrected acuity.
  • The maximum keratometry (Kmax): this parameter indicates the degree of central steepening of the central cornea. In keratoconus, the cornea undergoes a permanent deformation, which is characterized by a central steepening, and peripheral flattening. An increase in a Kmax value can significate a progression of the keratoconus.
  • The minimum keratometry value (Kmin): as for the Kmax, an increase in the value of this parameter can indicate a progression of the keratoconus.
  • The average keratometry value (or mean keratometry value, Kmean): as for the Kmax, an increase in the value of this parameter can indicate a progression of the keratoconus.
  • The simulated keratometry value (SimK): this value is usually a good estimate of the degree of corneal astigmatism. The deformation of the corneal dome always results in some level of astigmatism. An increase in the sim K value can suggest the progression of the keratoconus.
  • The corneal cylinder/astigmatism (Cyl):this parameter is another estimate of the level of corneal « toricity » (absence of revolution symmetry, whose optical consequence is induction  of astigmatism).  The progression of the corneal deformation results in an increase of the Cyl (for « Cylinder ») value.
  • The central corneal thickness (CCT) values:in keratoconus, the effect of repeated eye rubbing triggers a cascade of combined mechanical and enzymatic events which results in a reduction of the central thickness of the cornea.

The primary endpoint was the absence of evolution of keratoconus, with worsening defined as an increase of Kmax > 1.0D, and/or an increase of topographic astigmatism > 1.0D, and/or a decrease of the central corneal thickness > 5% from baseline. The statistical analysis was made by an independent statistician using paired student t-test.

All patients with a positive eye rubbing history are instructed to stop rubbing their eye(s) immediately. Those with an unhealthy sleeping posture are instructed to alter their sleeping position or prescribed eye shields. Patients who deny eye rubbing or are unaware of their habits are interrogated again at subsequent visits, and the accompanying relatives are questioned when necessary to corroborate their stories

Also, all patients with a positive eye rubbing history are instructed to stop rubbing their eye(s) immediately. Those with an unhealthy sleeping posture are instructed to alter their sleeping position or prescribed eye shields. Patients who deny eye rubbing or are unaware of their habits are interrogated again at subsequent visits, and accompanying relatives are questioned when necessary to corroborate their stories.

RESULTS
Evolution of Best Corrected Visual Acuity (BCVA) after cessation of eye rubbing in patients with keratoconus

There no decrease or a significant increase in BCVA at 3 years compared to baseline.

The size of the sample for the follow-up at 4 and 5 years is not large enough yet to ascertain the stability of this parameter.

logMAR chart keratoconus evolution.Evolution of the Best Corrected Visual Acuity (BCVA) expressed in the LogMAR unit. The lower the number, the better the visual acuity. 20/20 vision is equivalent to 0.0 logMAR, and acuities higher than 20/20 have a negative value. There was no statistically significant change in the visual acuity of our patients up to 3 years after the cessation of eye rubbing and/or protection of the eyes at night time.
Evolution of maximum keratometry and minimal keratometry after cessation of eye rubbing in patients with keratoconus

The average values of the Kmax (maximal curvature of the central cornea) and Kmin (minimal curvature of the central cornea) remain significantly stable at 3 years compared to baseline

The size of the sample for the follow-up at 4 and 5 years is not large enough yet to ascertain the stability of this parameter.

Evolution of the corneal curvature analyzed with the minimum (Kmin) and maximum (Kmax) curvature of the central cornea (as would be measured by a keratometer). There are no significant changes over the first 3 years after cessation of eye rubbing.
Evolution of mean keratometry and simulated keratometry after cessation of eye rubbing in patients with keratoconus

The average values of Kmean (mean value of the curvature within the central zone of the cornea) and SimK (simulated keratometry) remain significantly stable at 3 years compared to baseline

The size of the sample for the follow-up at 4 and 5 years is not large enough yet to ascertain the stability of this parameter.

Evolution of topographic astigmatism (cylinder) after cessation of eye rubbing in patients with keratoconus

The average values of Cyl (indicative of the level of corneal astigmatism/toricity) remain significantly stable at 2 years compared to baseline

The size of the sample for the follow-up at 3, 4 and 5 years is not large enough yet to ascertain the stability of this parameter.

Evlolution of the magnitude of the anterior corneal astigmatism (cylinder: Cyl). There is no significant change in the corneal astigmatism after cessation of eye rubbing.
Evolution of central corneal thickness (CCT) after cessation of eye rubbing in patients with keratoconus

The average values ​​of CCT (central corneal thickness, in µm) remain significantly stable at 4 years compared to baseline

The size of the sample for the follow-up at  5 years is not large enough yet to ascertain the stability of this parameter.

Results as graphs
CONCLUSION

Our on-going analysis of these cases has so far strongly supported the hypothesis that eye rubbing is the root cause of keratoconus.

There is a striking correlation between the more advanced side of keratoconus and the side that is rubbed more, as well as the sleeping position.

Complete cessation of eye rubbing has resulted in stabilization of the corneal deformation (average follow-up: 2 years). Interestingly, progression is only seen in patients who admit to being unable to abandon their eye rubbing habit.

If these results are confirmed in the future, it will enable us to conclude that the corneal deformation and thinning which are hallmarks of keratoconus are initiated and aggravated by the act of vigorous and repeated eye rubbing.


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