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36 EW FEATURE February 2011 Corneal diagnoses and systemic disease April 2012 Linking keratoconus and floppy eyelid syndrome to sleep apnea by Faith A. Hayden EyeWorld Staff Writer AT A GLANCE • Patients with keratoconus and floppy eyelid syndrome are at high risk for sleep apnea • Ophthalmologists should question patients with these conditions on their sleep habits • If a patient is suspected of having sleep apnea, he or she needs to be referred for a sleep study Does your patient need a sleep study? H as a patient ever nodded off in the exam chair or perhaps mentioned prob- lems sleeping? Does that patient have keratoconus or floppy eyelid syndrome (FES)? If so, pay attention. Keratoconus and FES are linked to sleep apnea, a dan- gerous sleep disorder characterized by breaks in breathing that's associ- ated with heart disease, stroke, hypertension, atrial fibrillation, congestive heart failure, and other deadly vascular diseases. Keratoconus, FES, and sleep apnea exist independently of each other. For example, many kerato- conus patients don't have sleep apnea, and many sleep apnea pa- tients don't have keratoconus. But it's not unusual to find a kerato- conus or FES patient with sleep apnea. What are the signs and symp- toms of sleep apnea, keratoconus, and FES? And if having one doesn't guarantee the development of the other, how are they linked? Signs and symptoms The signs and symptoms of sleep apnea are pretty well defined. They include daytime sleepiness, falling asleep while driving, and excessive snoring. The disease affects more men than women, and the National Institutes of Health estimates 1 out of 10 adults 65 and older have sleep apnea. "There's a huge epidemic of sleep apnea," said Michael A. Saidel, M.D., director, Cornea Service, University of Chicago. "It's a An example of FES Source: Francis S. Mah, M.D. major problem in the United States. It's associated with obesity and with all causes of morbidity and mortal- ity. It's a horrible disease." Keratoconus is a disease of young people and is characterized by central cornea thinning, causing the cornea to develop a cone shape. Symptoms include blurred vision and light sensitivity. "The cornea is like a bunch of layers of spaghetti, and the spaghetti has bonds between the multiple lay- ers," explained Charles Bouchard, M.D., John P. Mulcahy Professor of Ophthalmology, and chairman, Ophthalmology, Loyola University, Chicago. "In keratoconus, there seems to be a decrease in the num- ber of cells in the cornea and some elevation in inflammatory cytokines or inflammatory mediators. The thought is that over time, these col- lagen spaghetti fibers slide over each other and create that abnormal coni- cal shape." Like sleep apnea, FES is most fre- quently seen in overweight males. It's caused by a decrease in elastin in the eyelids, which allows the eyelids to be easily turned upward and be- come floppy. FES severity and symp- toms exist on a spectrum and can range from ocular redness and irrita- tion to corneal ulcer. "There's a lot of people in be- tween who have the disease, but it's under recognized because it's not symptomatic," Dr. Saidel said. What links them together? The link between sleep apnea, kera- toconus, and FES is known, but not well understood. A quick search on PubMed reveals a multitude of stud- ies linking FES and keratoconus to sleep apnea, but nothing hones in on one reason in particular. The dis- eases do have one common domina- tor: decreased elasticity and abnormal collagen. "With sleep apnea, there's ab- normal collagen and elasticity, and with keratoconus there's a collagen problem," Dr. Bouchard said. "And with floppy eyelid syndrome there's certainly alternation in elastic and collagen in the eyelids. The three diseases are linked by an abnormal- ity in collagen." Regretfully, curing sleep apnea won't help with the patient's FES or keratoconus. And of course, just be- cause a patient has keratoconus or FES doesn't mean he or she will de- velop sleep apnea. Drs. Bouchard and Saidel, however, do recommend screening all patients with FES and keratoconus for sleep apnea. "All keratoconus and floppy eyelid patients should be asked if they have trouble sleeping," Dr. Bouchard said. "Sleep apnea should be on the list of suspicious associ- ated diseases that general ophthal- mologists should be aware of. If they see keratoconus, they should think sleep apnea and ask the patient about it." A patient with keratoconus Source: Uday Devgan, M.D. Issues to go over with the patient include daytime sleepiness, prevalence of falling asleep at the wheel, and overall sleep hygiene. Obesity and dozing off in the exam chair are other tipoffs. "With those two things you should be very suspicious of sleep apnea and refer them for further testing," Dr. Saidel said. "You can't make the diagnosis of sleep apnea without having patients show they've had an episode of sleep apnea. This is typically done with a nighttime polysomnogram." Once identified, sleep apnea is treatable with continuous positive airway pressure therapy. Patients wear a mask attached to a hose and machine when sleeping that sup- plies a continuous stream of air, thus preventing apnea. "Sleep apnea is a serious dis- ease," Dr. Bouchard said. "[Patients] could die. The general ophthalmolo- gist should be aware of the associa- tion of sleep apnea, keratoconus, and floppy eyelid syndrome because patients may need a referral to a sleep study to confirm that." EW Editors' note: The doctors mentioned have no financial interests related to this article. Contact information Bouchard: cboucha@lumc.edu Saidel: msaidel@bsd.uchicago.edu