Visual impairment almost ended Steven Holcomb's career as a athlete, but he came back to win an Olympic gold medal in the 2010 bobsledding competition in Vancouver. By the time his vision had deteriorated to 20/500, he announced his retirement. But his coach helped him find a doctor willing to perform an experimental surgical procedure.
Keratoconus was Steven's diagnosis. This is a condition similar to astigmatism, where the cornea is “out of round”. In astigmatism, which is very common, the cornea is shaped like the side of a football. In keratoconus, the cornea is shaped like the end of a football.
Mild cases of keratoconus can be corrected with glasses or ordinary contact lenses. For other patients, hard contact lenses may be sufficient. For still more correction, patients may use piggy-back hard contacts on top of soft contact lenses. If these are not enough, then surgical options are available.
Steven Holcomb spent seven years getting eye exams and new contact lenses every few months. Rapid changes in vision are characteristic of keratoconus. When his refractive error was too much for external contact lenses, his doctor implanted an extra set of plastic lenses in his eyes. Intraocular lenses are widely used for cataract patients, whose natural lenses have become cloudy and are replaced. When the eye's natural lenses are left in place, the additional plastic lenses are called “phakic”, and are often used to correct high degrees of near-sightedness. Steven now has 20/20 vision.
Treatments for keratoconus in clinical trials include:
1. Orthokeratology contact lenses. These lenses reshape the cornea. Fitting them for keratoconus is considered a medical procedure and is covered by many health insurance plans.
2. Intacs corneal ring. This option is FDA approved for myopia (near-sightedness). It is a surgical procedure that is reversible, since the rings can be removed for future vision correction options. Corneal rings are appropriate for mild to moderate vision correction.
3. Collagen crosslinking with riboflavin and UV light.
4. Excimer laser ablation.
5. Sulfur hexafluoride.
6. Deep anterior lamellar keratoplasty (DALK).
7. Lamellar transplant with lyophilized corneas.
8. Penetrating keratoplasty with IntraLase or vacuum trephine.
References:
Steve Holcomb's story:
http://olympicsblog.dallasnews.com/archives/2010/02/hairopoulos-after-eye-surgery-us-bobsled.html
Clinical trials:
http://clinicaltrials.gov/ct2/results?term=keratoconus
Intacs corneal implants:
http://www.getintacs.com/
Orthokeratology contact lenses:
http://www.allaboutvision.com/contacts/orthok.htm
Other treatment options:
http://www.keratoconus.com/10.html
Clyde K. Kitchen, M.D., “Fact and Fiction of Healthy Vision: Eye Care for Adults and Children”, Praeger, 2007.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.