Keratoconus (from Greek: kerato- horn, cornea; and konos cone), is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal gradual curve.
Keratoconus is not a blinding disease in the truest sense of the word. The earliest signs of keratoconus are usually blurred vision and frequent changes in eye glasses prescription, or vision that cannot be corrected with glasses at all. Keratoconus requires a diagnosis from a competent eye doctor or opthamologist or Consultant trained not only in recognising the symptoms of KC but also observing the signs of keratoconus through direct measurement as well as inspection of the cornea at a microscopic level using a slit lamp. Topographies and pachmetry tests are also used.
The classic signs of keratoconus that the doctor will see when examining your eyes include:
- Corneal thinning
- Fleischer’s ring (an iron colored ring surrounding the cone)
- Vogt’s striae (stress lines caused by corneal thinning)
- scarring at the apex of the cone
The doctor will also measure the curvature of the cornea. This is done by:
- Keratometry: an instrument that shines a pattern of light onto the cornea. The shape of the reflection of the pattern tells the doctor how the eye is curved.
- Corneal topography: a computerised instrument that make three-dimensional “maps” of the cornea
Tiny fibres of protein in the eye called collagen help keep the cornea in place and keep it from bulging out. When these fibres become weak, they cannot hold the shape of the cornea which becomes more cone shaped over time. New research suggests the weakening of the corneal tissue that leads to keratoconus may be due to an imbalance of enzymes within the cornea. This imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, causing it to weaken and bulge forward.
Risk factors for oxidative damage and weakening of the cornea include a genetic predisposition, explaining why keratoconus often affects more than one member of the same family. The exact cause of keratoconus is uncertain, but has been associated with detrimental enzyme activity within the cornea. A genetic link seems likely, as the incidence rate is greater if a family member has been diagnosed.
Keratoconus also is associated with overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation from allergies. Other research suggests a hormonal link may exist. The condition happens more often in people with certain medical problems, including certain allergic conditions. It’s possible the condition could be related to chronic eye rubbing. Most often, though, there is no eye injury or disease that can explain why the eye starts to change.
Keratoconus can cause severe distortion of vision, with multiple images (ghosting), streaking and sensitivity to light (halos).
It is often diagnosed in the patient’s teenage years and gets worse in the twenties and thirties. As keratoconus is bilateral in over 95% of cases, affecting both eyes, the deterioration in vision can affect the patient’s ability to drive or read normal print, operate machinery, computers and so on. In most cases, corrective contact lenses are effective enough to allow the you to continue to drive legally and likewise function normally, which includes continuing to work, play sports and live a normal life.
Further progression of the disease may require surgery including intrastromal corneal ring segments (Intacs, ferrara rings), corneal collagen cross-linking (CXL, C3R) or corneal transplantation/ corneal graft. However, despite the disease’s unpredictable course, keratoconus can often be successfully managed with little or no impairment to the patient’s quality of life.
WHO GETS KERATOCONUS?
Keratoconus affects around one person in 500, and is more prevalent in black and Asian communities, and people with Down’s Syndrome often have keratoconus. Keratoconus has also been linked to several other eye diseases, including retinitis pigmentosa, retinopathy of prematurity and vernal keratoconjunctivitis, as well as systemic diseases such as Leber’s congenital amaurosis, Ehlers-Danlos syndrome, and osteogenesis imperfecta.
There also seems to be a higher prevalence of keratoconus in those with autism and Aspergers. This can make wearing lenses and getting the right treatment options a little harder.
Laser vision correction surgery such as LASIK– can be dangerous for people with Keratoconus. Anyone with even a small degree of keratoconus should not have LASIK surgery. Very often people are diagnosed with KC when they go to find out about having LASIK. Some people with thin or weak cornea have LASIK and then develop corneal ecstasia which presents like keratoconus and can be treated in the same way.
Keratoconus can be tricky to live with but with the right treatment you can live a normal life, even if you have to adapt some things as you go. It should not rule your life. Read positive real life experiences about living with keratoconus from people from all over the world, and gain insight into this condition, You are not alone with the original #kcfamily
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