How to recognize and treat a corneal cone
Non-specific symptoms of corneal cone can make the diagnosis too late. If there have already been cases of the disease among our loved ones, or if the deterioration of visual acuity is accompanied by symptoms such as the halo effect around the light source and blurring of the image, and subsequent changes of glasses are not effective, it is essential to ask an ophthalmologist to diagnose the disease.
Corneal cone diagnosis includes:
- in-depth interview,
- Assessment of visual acuity to distance,
- Keratometry (measurement of the curvature of the cornea),
- Retinoscopy (examination of the refractive state of the eye),
- Slit-lamp examination of the cornea,
- corneal topography.
During a routine eye exam, the early form of corneal cone may go unrecognized. Modern diagnostic devices make it possible to detect the cone even at the stage when it is still in its infancy. Corneal cone develops most dynamically in two age groups: adolescents and those in the 30-35 age range. The progression of the cone can proceed very quickly and rapidly, but after such a marathon, it can also stop and no longer develop further.
Treatment of corneal cone in its mildest phase is often reduced to the use of glasses or contact lenses. However, as the disease progresses, these become insufficient. The patient has to change glasses/lenses frequently, and is still unable to achieve the desired quality of vision. This is because corneal cone is not a visual defect, but pathological changes within the cornea proper and subsequent layers. The abnormal structure of the cornea results in its thinning. The pressure in the eyeball causes the thinnest part of the cornea to bulge out, taking just the shape of a cone.
During the examination, the doctor notices the following changes:
- Paracentral convexity of the cornea with associated stippling
- Deposition of iron deposits within the basal layer of the corneal epithelium – Fleischer’s ring
- V-shaped protrusion in the lower eyelid with the eyes down – Munson’s sign
- damage to Bowman’s layer
- Fine striae formed in the cornea under tension – Vogt lines
To assess the condition of the patient’s eyes, a comparison is made between the results of an individual corneal topography, such as from a year ago and from the current examination. Depending on the changes that have occurred during this time, measures are taken to stop the changes occurring in the cornea.
Corneal cone therapy proceeds in two stages:
- Stopping the progression – and in some cases reversing – of lesions.
- The aim is for the patient to achieve the greatest possible visual acuity. If the corneal relief is small, soft contact lenses are used, when the relief is large hard lenses come into play.
CROSS-LINKING (named after the effect it produces) – also known as cross-linking of bonds, cross-collagenization of the cornea or CXL – causes the cornea to stiffen and increase its mechanical resistance.
Stiffening of the cornea is accomplished by increasing the number of bonds between the collagen fibers that build it. It occurs under the influence of UVA irradiation of the cornea. In order to increase the sensitivity of the superficial layers of the cornea to UVA radiation, it is soaked in a special photosensitizing substance, riboflavin (vitamin B2). Clinical studies confirm that the action of riboflavin contributes to slowing or stopping the disease and, in some cases, its regression. Thus, the procedure makes it possible to bypass corneal transplantation.
