An Inside Look at the Eye
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The condition usually begins between the ages of 10 and 25. Both eyes are always affected, causing major changes in vision and requiring frequent changes in prescription for eyeglasses or contact lenses in many people. The cause is unknown, but people are more likely to develop keratoconus if they have any of the following:
Another family member who has keratoconus
A tendency to develop many allergies (sometimes called atopy)
A tendency to vigorously rub their eyes
Lax eyelids
Certain connective tissue disorders (for example, Ehlers-Danlos syndrome Ehlers-Danlos Syndromes Ehlers-Danlos syndromes are rare hereditary disorders of connective tissue that result in unusually flexible joints, very elastic skin, and fragile tissues. These syndromes are caused by a defect... read more
, Marfan syndrome Marfan Syndrome Marfan syndrome is a rare hereditary disorder of connective tissue, resulting in abnormalities of the eyes, bones, heart, blood vessels, lungs, and central nervous system. This syndrome is caused... read more 
, and osteogenesis imperfecta Osteogenesis Imperfecta Osteogenesis imperfecta is a hereditary disorder that disrupts the proper formation of bones and makes bones abnormally fragile. This disorder is caused by mutations in certain genes. Typical... read more 
)Disorders that are apparent at birth and cause poor vision (for example, Leber congenital amaurosis, retinopathy of prematurity Retinopathy of Prematurity (ROP) Retinopathy of prematurity is a disorder of premature infants in which the small blood vessels in the back of the eye (retina) grow abnormally. Retinopathy of prematurity is strongly associated... read more , and lack of an iris in the eye)
Treatment of Keratoconus
Contact lenses
Ultraviolet light treatments
Corneal ring segments
Corneal transplantation
Contact lenses often correct the vision problems better than eyeglasses. There are many designs of contact lenses (for example, rigid gas permeable, hybrid, scleral) that may be tried depending on the abnormal shape of the cornea. Some may be well tolerated and give good vision. But, sometimes the change in corneal shape is so severe that any contact lenses either cannot be worn or cannot correct vision.
Ultraviolet light treatments that stiffen the cornea (called collagen cross-linking) are useful in early keratoconus to prevent further progression.
The insertion of corneal ring segments (objects that change the shape of the cornea to help correct refraction) seems to improve vision by allowing people to better tolerate wearing contact lenses. Corneal ring segments prevent certain people from needing corneal transplantation.
In severe cases, corneal transplantation Corneal Transplantation Corneal transplantation (keratoplasty) is a common and highly successful type of transplantation. A scarred, severely painful, perforated, misshapen, or cloudy cornea (the clear layer in front... read more may be needed to restore vision.
