What are the symptoms, causes and treatment of Keratoconus?

Keratoconus is an uncommon condition in which the normally round, dome-like cornea becomes thin and develops a cone-like bulge

• Keratoconus literally means “cone-shaped cornea”
• It is derived from the greek word for cornea (‘kerato’) and cone shaped (‘conus’)
• It also results in the irregular surface of the cornea which cause a distortion of the image which is projected to the brain
• It makes some activities difficult, such as driving, typing on a computer, watching television or reading

Causes of Keratoconus

The causes of keratoconus is still not known

Some researchers believe that genetics play a role, since an estimated 10 percent of people with keratoconus also have a family member with the condition

Recent research on keratoconus shows that enzymes imbalance in the cornea causes the weakening of the eye tissues

This imbalance cause the weakening and the increase in size of the cornea. This is due to the oxidative damage caused by free radicals

Keratoconus also is associated with overexposure to ultra violet light from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation

Symptoms

Keratoconus usually affects both eyes, though symptoms in each eye may differ. Symptoms usually start to occur in people who are in their late teens and early 20s and may include:

• Blurring of vision
• Distortion of vision
• Increased sensitivity to light
• Glare
• Mild eye irritation

Treatment

In the early stages of keratoconus, eyeglass or soft lenses may help, but as the disease progresses and the cornea thins and becomes increasingly more irregular in shape, glasses and regular soft contact lens designs do not provide adequate vision correction.

Types of treatment:

• Custom soft contact lenses
• Gas permeable contact lenses
• “Piggybacking” contact lenses
• Hybrid contact lenses
• Scleral and semi-scleral lenses
• Intacs
• Corneal cross linking
• Topography-guided conductive keratoplasty
• Corneal transplant

Custom soft contact lenses

• These lenses are designed specially to ameliorate the vision from mild to moderate keratoconus
• Measurements of the cornea is taken into detail and contact lenses are made on order

Gas permeable contact lenses

• Gas permeable contact lenses are lenses made up of rigid materials
• They are quite uncomfortable
• It enables the lenses to curve over the irregular cornea to give a regular surface for the proper refraction of light so as to improve the vision

“Piggybacking” contact lenses

• Because of the uncomfortability of the gas permeable contact lenses, some eye care practitioners prefer “Piggybacking”
• It is two different types of contact lenses in the same eye
• It is the placing of a soft contact on the cornea before fitting the gas permeable lenses

Hybrid contact lenses

• These lenses are combined of two portions ; a highly oxygen permeable rigid centre and soft peripheral
• The central gas permeable zone of the lens vaults over cornea for increased comfort, and it provides crisp optics
• The peripheral soft, usually made of silicone hydrogel material provides greater oxygen transmissibility

Scleral and semi-Scleral lenses

• They are large diameter gas permeable lenses, where the periphery and edge of the lens rest on sclera
• Scleral lenses cover a larger portion of the sclera compared to semi scleral lenses which cover a smaller area

Scleral and semi-Scleral lenses

• These lenses don’t apply pressure to the cornea, hence providing a more comfortable fit
• They are more stable than conventional gas permeable contact lenses, and they move with each blink because they cover only a portion of the cornea

Intacs

• These surgically applied tiny plastic inserts are placed just under the eye’s surface in the periphery of the cornea
• Intacs help in reshaping the cornea for a clearer vision
• These implants have the advantage of being removable and exchangeable

Corneal cross linking

• It strengthens corneal tissue to halt bulging the cornea in keratoconus
• With epithelium-off cross linking , epithelium is removed to allow entry of riboflavin into the cornea , which is then activated with UV light
• With epithelium- on method (transepithelial cross linking), the corneal surface is left intact
• This method requires more time for riboflavin to penetrate cornea but include less risk of infection, less discomfort and faster visual recovery

Topography-guided conductive keratoplasty

• Recent research has been done using radio waves so as to make the irregular surface of a disease cornea smooth