What Is Keratoconus?
Keratoconus is a corneal eye condition affecting around 1 in 2000 people. The disease weakens the cornea making it thinner and causing it to change shape.
Usually the condition starts to manifest itself from the early teens upwards but can show signs earlier in life.
Signs And Symptoms
Frequent visual prescriptions changes, blurred vision or glasses that are not correcting vision are the initial signs of keracotonus.
Other symptoms include:
- Light sensitivity.
- Eye strain, pain and irritation.
- Halo around lights and difficulty driving at night.
Theories regarding the cause of keratoconus are few and only a number of contributing factors can be associated with the disease.
Genetically less than 1 in 10 or patients have a blood relative with the condition and more commonly will be an isolated case within a family.
Eye rubbing damages corneas with keratoconus and patients with allergies (atopic disorders) are at a higher risk. Atopic disorders include hay fever, eczema, asthma and food allergies.
Poor fitting contact lenses can also be a possible cause.
It is also thought that corneas affected by keratoconus are unable to naturally repair day to day damage by means of cell metabolism (free radicals). Structural damage of the cornea causes it to bulge due to the free radicals not being flushed away efficiently, thus producing tissue damage.
Degenerative conditions, like Fuch’s endothelial dystrophy, happens as the ageing process causes the lining of the cornea to deteriorate. Cells weaken and clearance of fluid causes keratoconus.
If an opthalmist suspects a patient to have keratoconus he will perform an examination with a slit lamp. This will detect:
- Corneal thinning.
- An iron coloured ring around the cone (Fleischer’s ring).
- Cone scarring (Apical scarring).
The curvature of the cornea will also be checked by shining a pattern of light across the eye to detect the reflection on the cornea.
Most patients affected by keracotonus will only experience mild symptoms which are treatable by prescription glasses or contact lenses. However, if the disease progresses corneal laser treatment or transplants may be required. Which procedure will be successful will depend on which part of the cornea is affected.
PK (Penetrating Keratoconus) is the removal of the damaged cornea. This full thickness transplant is then replaced by the donated cornea under local or general anaesthetic and stitched into place.
Partial thickness transplants can also be performed where only part of the cornea is removed and replaced.
ALK and DALK procedures work in the same way as PK but only replace the outer layers of the cornea. These are suitable for transplants on the front portion of the cornea and stitches are also used to fix the donated cornea.
DSEK and DMEK surgery replace the inner layers of the cornea. Patients need no stitching in these procedures as a temporary air bubble is used to hold donated tissue.
Corneal Collagen Cross-Linking
Abnormal anchoring fibrils that secure and stabalise the cornea can cause the bulging, steeping and irregular shape of the cornea present in keratoconus. To improve these corneal problems, collagen cross-linking surgery may be performed.
This treatment involves prescription riboflavin drops being administered to the cornea. Ultraviolet light activates the drops increasing the collagen cross-linking with the cornea, thus strengthening it.
The procedure can be performed in two ways:
1. By removing the corneal epithelium (a thin layer covering the eye’s surface) allowing the riboflavin to penetrate quickly.
2. By Transepithelial Corneal Cross-linking, leaving the epithelium on and allowing a longer period of time for the riboflavin to penetrate.
This procedure is used to slow down the progression of keracotonus and diminish the requirement for corneal transplants. Glasses and contact lenses may still be needed after surgery but sight will be greatly improved.
Patients will benefit from the cross-linking procedure due to:
- Recovery time being cut as no cutting implement is being used.
- Rejection of donated tissue and corneal transplants are no longer relevant.
- The risk of infection is greatly reduced due a non-stitching correction.
Always consult a medical professional to investigate which treatment or surgery will be beneficial to your individual circumstances.