This is the condition that develops when the cornea which is the round dome-shaped part of the eye thins resulting in the cone-shaped bulge to occur. This can affect the transparency of the cornea that impairs the ability to focus properly resulting in poor vision. This condition is estimated to affect around 1 in 1,000 individuals and appears to be common among the Asian heritage.
Causes
To produce the visual images, the light travels into the cornea, to the retina and then to the brain. The normal shape of the cornea is round in the center and flat towards the outer edge. Individuals with this condition have the cone shaped cornea with an irregular surface which can distort the image projected onto the brain. Although the exact cause of Keratoconus is not known, research indicates that it can be associated with allergic diseases such as asthma, Down’s syndrome and Marfan’s disease. The genetic factor appears to play a role as around 1 in 10 people with this condition also have parents who exhibit this disorder. This usually occurs among individuals in their late teens or early 20s that continues to deteriorate over a period of 10 to 20 years.
Symptoms
This condition can affect both the eyes which can cause very different vision between the eyes. Accordingly, the symptoms differ in each eye which can also change over time. As the cornea shape changes and thins, it can result in scars and loss of transparency thus affecting the eye’s ability to focus. The early stage includes mild blurring, eye redness, itching, slightly distorted vision and sensitivity to light. The later stage of this condition can include more blurred or distorted images, increased nearsightedness and the inability to wear contact lenses as they may not fit properly. This condition usually takes time to progressively deteriorate although in some cases it can also get worse quickly. The cornea can also scar, losing its smoothness and become less clear which can create the distorted and blurry vision.
Diagnosis
This condition can be diagnosed with the routine eye examination. The ophthalmologist will examine the eye and measure the curve of the cornea which can indicate the change in the shape. The tests may include vision (reading chart), refraction (Spectacle test) and corneal scan (pentacam).
Treatment
The treatment for this condition in the early stage can consist of spectacles or soft contact lenses to correct vision. When the cornea becomes thin, rigid gas permeable contact lenses are required. If the individuals have difficulty with contact lenses, a procedure known as phototherapeutic keratectomy or nebulectomy may be initiated that removes the scar from the cornea making the individual more contact lens tolerant. In the severe cases, the corneal transplant may be required when the contact lenses become ineffective. As this condition takes time to deteriorate, these individuals are often advised for repeat assessment for up to five years.
References
http://www.keratoconus.com/10.html
https://www.aao.org/eye-health/diseases/keratoconus-diagnosis
