How doctors of optometry can diagnose a rare disorder
Fabry disease is a rare genetic disorder, but one of its hallmark signs is easily visible in the cornea during a routine exam. Doctors of optometry who are able to diagnose this often overlooked disease can help patients receive critical treatment.
Fabry disease, which is estimated to occur in 1 in 40,000 live births, is a lysosomal storage disorder in which the enzyme that normally breaks down a particular fatty substance called globotriaosylceramide is defective. This causes the fat to build up over time in blood vessels, which can lead to kidney damage, heart disease and stroke. Fabry disease symptoms usually show up in childhood as pain and discomfort in the hands and feet. Symptoms include the inability to sweat, spontaneous diarrhea and a dark red rash in the area from their navel to their knees. Patients may go undiagnosed for 15 to 20 years or more.
It is not difficult to discover—if doctors know what to look for. Nearly all patients with Fabry disease have corneal verticillata, a golden-brown "whorling" pattern typically seen in the inferior corneal epithelium during a regular exam.
"The whorling is very thin, half a micron thick, so it has no effect on acuity," says Albert Morier, M.A., O.D., an associate clinical professor of ophthalmology at Albany Medical College in New York.
Certain medications, such as the anti-malarial chloroquine and heart drug amiodarone, also can cause whorling, so doctors should rule out prescription drug use as a cause. However, patients may be taking amiodarone for heart issues related to undiagnosed Fabry disease. Doctors should refer the patient to a genetic specialist, who will conduct DNA testing to confirm Fabry disease. There is no cure, but patients can benefit from enzyme replacement therapy.
Make a diagnosis, make a difference
Leslie O'Dell, O.D., diagnosed a teenage girl and her mother with Fabry disease after hearing a lecture about it. "You couldn't miss the whorling pattern [in the girl's eye], so I switched to look at her mom and saw it in her, too," says Dr. O'Dell, director of the Dry Eye Center of PA at Wheatlyn Eye Care in Pennsylvania.
Both mother and daughter experienced burning in their hands and feet when they had a fever, and an elderly female relative had died of kidney disease that had been attributed to diabetes. After Dr. O'Dell referred both patients to a genetic specialist, they started on enzyme replacement therapy. Five years later, Dr. O'Dell says, "It's making a big difference in how they feel, and the daughter is able to go away to college."
Chris Shiomos, O.D., who practices in Syracuse, New York, diagnosed a 36-year-old female patient after noticing the whirling in both her eyes. The patient said her whorling had been spotted often since she was 12 years old—for 24 years—but no clinician ever knew what caused it.
Dr. Morier, who travels the country to present on Fabry disease, credits the late James Riley, O.D., of Wilton, New Hampshire, for calling doctors' attention to the disorder. Over 10 years ago, Dr. Riley discovered the whorling in a female patient in her 60s and diagnosed Fabry disease. After that, 43 members of her family were also identified with the genetic mutation.
"An optometrist making a diagnosis and acting on it can have a huge effect," Dr. Morier says.
Low Vision Awareness Month is a perfect opportunity to consider implementing such services in your practice and to ensure you have the right connections for necessary referrals to other doctors of optometry who provide this essential care.
Researchers found only about 30% of patients with diabetes abide by four diabetes care practices—including eye exams.