Dear Doctor: My eyes are so dry, they often feel as if I have sand in them. I use drops, but they don't always work. Is there anything else I can do? And will this hurt my vision over time?

Dear Reader: No doubt you're frustrated. If it's any comfort, your doctor probably is too. People suffering from dry eyes are frustrated because of the constant irritation; doctors are frustrated because they don't have a miracle cure. The symptoms of dry eyes vary. Like you, many patients complain of a gritty or sandy sensation. Some also report red or watery eyes, a burning feeling, light sensitivity, blurred vision or a combination of these symptoms. Paradoxically, excessive tearing can also be a sign of dry eyes. Rarely, however, does prolonged dry eyes lead to scarring of the cornea or permanently altered vision.

That's fortunate, because 14.5 percent of Americans report having regular dry eye problems, and the likelihood increases with age. The condition is more common in women, especially those undergoing menopause, as well as in people with certain chronic illnesses such as diabetes and Parkinson's disease. People who have had laser eye surgery, wear contacts or use medicated eye drops also have a greater rate of dry eyes, as do people who have allergies.

As for treatment, it's important to look at the possible cause. Some medications, such as antihistamines, antidepressants, niacin, estrogens and the arrhythmia drug amiodarone can cause dry eyes. So can the autoimmune disease Sjogren's syndrome, which leads to inflammation of tear ducts, death of cells in the ducts and decreased formation of tears. Sjogren's, which is accompanied by dry mouth, can be diagnosed with blood tests and other screenings that evaluate production of tears and saliva. Other conditions can affect the tear ducts as well, such as sarcoidosis, lymphoma and diabetes.

Eyelid health is also important. Normally, Meibomian glands in the eyelid produce an oily substance that prevents tear evaporation and helps trap tears upon the eyeball. Inflammation of the lid margin, termed blepharitis, causes these glands to malfunction, leading to dry eyes. Treatment of blepharitis includes lid scrubs (using baby shampoo and a warm wet cloth), lid massage, warm compresses and artificial tears.

Speaking of artificial tears, these drops add viscosity to the fluid surrounding the eye and thus maintain a natural tear covering the eye. Adding one drop to each eye three to four times per day will improve symptoms. Note that some people have sensitivity to the preservatives in artificial tears, so using preservative-free tears may be helpful.

For people with inflammatory conditions such as Sjogren's syndrome or blepharitis, the immunosuppressive eye drop cyclosporine, applied twice a day, can significantly improve the symptoms of dry eyes.

A newer eye drop, lifitegrast, decreases inflammation in the eye, with twice-a-day application leading to significant improvement of symptoms. Note, however, that the medication can also cause eye irritation and taste abnormalities.

Not all treatments are drug-related. Omega-3 fatty acids with EPA, DHA and flaxseed oil can enhance tear production, decrease tear evaporation and improve overall symptoms. Similarly, diets deficient in omega-3 fatty acids have been linked to increased rates of dry eyes.

In summary, give artificial tears a try, and increase your intake of omega-3 fatty acids. Also, please see an ophthalmologist. He or she can determine whether an inflammatory disorder, such as blepharitis or Sjogren's, is the cause of your symptoms.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm 79 years old and recently contracted mumps. I've never been so ill, and in fact, I am still suffering the aftereffects. Please help other older adults understand whether they should get the mumps vaccine.

Dear Reader: Although mumps is nowhere near as common in the United States as it once was, outbreaks continue to occur. Last year, mumps cases hit a 10-year high with 6,366 reported to the Centers for Disease Control and Prevention. In 2012, there were just 229 cases. By contrast, prior to 1967, when the mumps vaccination program was launched, about 186,000 cases were reported each year. However, that number is probably too low due to underreporting.

Mumps is caused by a virus that spreads via contact with saliva or mucus from the mouth, nose or throat of an infected person. It is carried via airborne droplets from the upper respiratory tract through coughing, sneezing or even talking. The virus can also be transferred through shared items like plates, cups and cutlery, and on objects or surfaces that have been touched by the unwashed hands of the infected person.

As with many contagious diseases, the infected person begins shedding the virus before symptoms become apparent. He or she will continue to be contagious for up to five days after becoming visibly ill. These symptoms include fever, headache, body aches and pains, exhaustion and lack of appetite. Swollen and tender salivary glands in front of one or both ears give sufferers the puffy cheeks and swollen jaw that is associated with the disease. Some patients experience hearing loss, but it is rarely permanent.

Adults who get mumps are at greater risk for complications than are children. These can include inflammation of: the membrane around the brain or spinal cord (known as meningitis), the testicles, breast tissue, ovaries or pancreas. The most serious complication is encephalitis, which is inflammation of the brain itself. It can lead to permanent disability or even death.

Mumps can be prevented with the MMR vaccine, which also confers immunity to measles and rubella. The CDC recommends two doses of the vaccine for children, the first at 12 to 15 months of age, and the second at 4 to 6 years of age. Teens and adults should also stay current on MMR vaccinations. Pregnant women should not get the vaccine, and women should wait at least four weeks after vaccine administration before becoming pregnant.

Because a number of cases of mumps have occurred in people who have had the two-dose vaccine, there is now a debate about whether immunity confers through adulthood. A recent study in the New England Journal of Medicine analyzed data from a mumps outbreak at the University of Iowa during the 2015-2016 school year. Students who had a mumps booster had a 78.1 percent lower risk of mumps than those with the just the two-dose vaccine. To address waning immunity, researchers suggest that a mumps booster may be called for.

We advocate for vaccination and help our patients stay current. And for anyone with questions or concerns about the vaccine, please do talk to your primary care physician.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: A friend of mine was diagnosed with methicillin-resistant Staphylococcus aureus, or MRSA. How does a person even contract such a disease -- and what does it do to you?

Dear Reader: Methicillin-resistant Staphylococcus aureus, or MRSA, is a bacterium that is resistant to methicillin and other penicillin-related antibiotics. These drugs normally bind to a specific protein on the bacterium, leaving it unable to produce a cell wall. MRSA, however, has a gene that produces a protein that doesn't bind to methicillin or its cousins, making it harder to defeat.

People can acquire MRSA in two ways. One is through a health care setting, either in a hospital, nursing facility, surgical center or dialysis facility. Infections acquired in those settings can manifest between 48 hours and a year after exposure. They're more likely if a patient is over-prescribed penicillin-related antibiotics (making them more resistant to the drugs); is in a room or setting next to somebody with a MRSA infection; or is on dialysis. Although hospitals take painstaking measures to ensure a sterile environment free from harmful bacteria, MRSA forms a biofilm that attaches to inert objects, such as catheters and breathing tubes. From there, it can more easily invade the body. It can also attach to the hands of health care workers and many surfaces, and, from there, make its way to patients.

The second way to acquire MRSA is within the community. Outbreaks have been noted among sports teams, in childcare centers, among military personnel and in prison populations. Even animals can carry the bacterium and pass it on to a human host. Such cases are predominately skin infections, including cellulitis, folliculitis and abscesses. The bacterium can also be passed among household members. A 2012 study of 148 MRSA-infected patients found that 19 percent of their household contacts had colonized the bacteria.

In humans, MRSA colonizes within the nose, within the throat and upon the skin. That doesn't mean it causes infections, but rather that it's lurking there, ready to cause an infection should a person's immunity be compromised. From there, it can also spread to others, who may be more susceptible. A 2010 study of hospitalized patients found that 7 percent had colonized MRSA. In two 2008 studies of health care workers in the emergency room, between 4 and 15 percent had colonized MRSA within their nose.

MRSA not only causes skin infections, but can lead to pneumonia, infections of the bone and within joints, infections of the heart valves, and urinary tract infections. The infections can seep into the blood and pass to multiple organs. In 2005, MRSA led to an estimated 18,500 deaths in the United States.

All is not lost, however. The spread of MRSA can be controlled in hospitals and outpatient clinics if health care workers wash their hands after seeing patients, and if they use gloves and masks when seeing patients with MRSA. In households with a MRSA-infected family member, residents should be extremely diligent about hand-washing. The antiseptic chlorhexidine is especially effective at removing the bacteria from the skin. Further, those diagnosed with colonized MRSA in the nose can take the nasal antibiotic ointment Mupirocin.

Also, I'll say it again: Limiting the use of antibiotics will decrease the chance of bacterial resistance to them -- and decrease the chance of MRSA.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)