What is Keratoconus?
Keratoconus is a common corneal condition occurring in more than 1 in 1000 people. The condition typically starts in adolescence and early adulthood with an uncertain cause.Progression is unpredictable, but in extreme cases, vision deterioration can require corneal transplant surgery.
Corneal cross-linking (CXL), a newly FDA-approved treatment for keratoconus, uses a combination of ultraviolet-A light irradiation and application of riboflavin (vitamin B2) eye drops to stabilize the cornea. Two members of the USC Roski Eye Institute faculty have been at the forefront of advancing CXL treatment for keratoconus. The cornea is the clear surface on the front of the eye. It is usually a regular spherical dome and is responsible for focusing images. The cornea consists of layers that are linked to each other by collagen. If the collagen cross links are lost due to keratoconus, there is a progressive corneal thinning and stretching. Keratoconus causes the cornea to bulge forward, producing an irregular cone shape that distorts how images are focused. Due to the irregular corneal shape it can be difficult to correct vision with glasses or soft contact lenses.
Signs and Symptoms
Early signs of keratoconus are usually blurred vision and frequent changes in eyeglass prescription, or vision that cannot be corrected with glasses. Other symptoms include increased light sensitivity, eye strain and irritation with excessive eye rubbing. Keratoconus symptoms usually appear during the late teens and early twenties.
Although the cause of keratoconus is unknown, it is believed that the risk factors include: eye rubbing, a family history of keratoconus, genetic predisposition, certain systemic disorders such as Down Syndrome that can affect approximately 50 percent of family members. It can also be a random event. It affects men and women in equal proportions and is bilateral in 90% of patients.
Research at USC Roski
Farhad Hafezi, MD, PhD, Adjunct Clinical Professor of Ophthalmology at the USC Roski Eye Institute and Professor of Ophthalmology at the University of Geneva, Switzerland was among the earliest investigators in Europe to study and utilize CXL both in the laboratory and in patients with progressive keratoconus and post-LASIK ectasia.
J. Bradley Randleman, MD, Professor of Ophthalmology and Director of the Cornea, External Disease, and Refractive Surgery Service at USC, was a principal investigator for both of the FDA-sponsored US clinical trials that generated the data leading to CXL approval in 2016. The two have co-authored multiple publications on CXL and co-edited the first academic textbook on the topic, Corneal Collagen Cross-Linking, in 2013. A second edition came out in late 2016.
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