The cornea is the outermost layer of the eye. It is the transparent, domeshaped surface that covers the front of the eye. It plays a vital role in focusing your vision, accounting for approximately two-thirds of the eye’s total optical power.
What is keratoconus?
Keratoconus is a vision disorder that results from an irregularly shaped cornea, which prevents light from focusing correctly on the retina. In keratoconus, the normally round cornea becomes thin and bulges outward like a cone. This abnormal shape prevents light from entering the eye and being focused correctly on the retina, causing distortion of vision and resulting in blurred vision and sensitivity to bright lights.
In its earliest stages, keratoconus causes slight blurring and distortion of vision, as well as increased sensitivity to glare and light. These symptoms usually appear in the late teens or late 20s. As it progresses, the cornea bulges more, and vision may become more distorted; your eyeglass prescription may also change. Keratoconus may progress for 10-20 years and then slow in its progression. There are no medicines that can prevent the disorder from progressing.
Each eye may be affected differently. In a small number of cases, the cornea may swell, causing a sudden and significant decrease in vision. The swelling occurs when the strain of the cornea’s protruding cone-like shape causes a tiny crack to develop. The swelling may last for weeks or months as the crack heals and is gradually replaced by scar tissue. If this sudden swelling does occur, your doctor can prescribe eyedrops for temporary relief.
Symptoms of keratoconus include:
Distorted vision at all distances
Glare
Ghost images – the appearance of several images when looking at one object
Multiple changes to eyeglass prescription
Your doctor can determine the presence of keratoconus using a slit lamp evaluation or by examining the surface of the cornea through corneal topography.
There is no known cause for keratoconus, although experts have theorized many causes, including preexisting medical conditions, heredity, allergies, and eye rubbing. It is a gradual, slow-moving disease, which typically starts in the late teens to early twenties and may continue for several years.
Eyeglasses or soft contact lenses may be used to correct the mild nearsightedness and astigmatism that is caused by the early stages of keratoconus.
As keratoconus progresses, other treatments may include:
Specifically-designed soft contact lenses: Custom soft contact lenses that are designed to help correct keratoconus
Rigid gas permeable contact lenses: Gas permeable (GP) lenses are used to adequately correct vision for irregular corneas by covering or masking them with the smooth outer surface of the contact lens. The contact lenses must be carefully fitted, and frequent checkups and lens changes may be needed to achieve and maintain good vision.
Scleral contact lenses: larger diameter lenses that vault over the entire cornea. Like the GP lenses, scleral contact lenses must be carefully fitted, and frequent checkups and lens changes may be needed to achieve and maintain good vision.
Corneal cross-linking (CXL): UV light and eye drops are used to help stiffen your cornea
Corneal transplant: In cases where contact lenses cannot correct the irregular shape of the eye, surgical options are available to repair the cornea. Laser surgery is not an option, however, as there is a high probability of further damaging the cornea.
