Suspicious forms of Keratoconus
Suspicious forms of Keratoconus ("Keratoconus suspect") belong to the group of corneal anomalies that are grouped under the name of » subclinical keratoconus « : Their diagnosis is based on the specular topography of Placidowhich reveals anomalies, which, without being sufficiently pronounced to make the diagnosis of Keratoconus, evoke the possibility of a intermediate form, little or no progressive disease. One speaks for example of form fruste in front of a topographical picture very little modified on one eye, while the other one has a frank Keratoconus. We know today that this type of asymmetry between the right and left eyes of the same patient is explained by a difference between intensity and/or frequency and/or duration of the eye rubbing.
There are no clinical signs of affection outside of a possible refractive anomaly (the examination to the slit lamp is normal, the cornea is transparent, the best corrected visual acuity retained).
Myopia and a Astigmatism of corneal origin (typically oblique or inverse direction) are often associated with the infra-clinical forms of keratoconus.
Generally, the presence of an allergic terrain (atopy) is often noted in the patient concerned and/or the notion of overwork, chronic fatigue, intense studies, prolonged work on screen, stress, etc. These elements have in common to promote the occurrence of itching (pruritus) marked ocular,... which caused the realization of eye rubbing repeated.
These frictions, beyond a certain frequency, intensity duration, can cause in the long term a permanent deformation of the cornea which, when it is weakly pronounced, is akin to what is designated as a suspicious form of keratoconus.
The keratoconus itself is no other than the marked and permanent corneal deformation, which is itself the translation of repeated mechanical stress (rubbing).
Suggestive signs of a suspicious form of keratoconus
In the absence of an automated detection index, the suspicion of the presence of an infra-clinical keratoconus may be evoked before:
-one asymmetry of the cornea: A more accentuated camber in lower or inféro temporal than in superior, a deviation of the most arched hemi-meridians (SRAX)
-reduced corneal thickness (ex: 500 microns and less for the minimum thickness)
-A lower deflection of the most fine point of the cornea (maps of thickness/tomography)
-a topographical discordance between the earlier rise and the subsequent elevation of the cornea (see article dedicated to the corneal elevation of suspicious forms of Keratoconus)
-a discordance between topographic aspect of the right eye and the left eye (low enantiomorphism)
-a (boost) evolution of the topographical anomalies in time.