Do you suffer from gritty, burning, red eyes? Do they feel dry, or sometimes excessively watery? Then you’re not alone. Estimates are that more than three million women over 50 and over 1.5 million men over 50 are affected by dry eye syndrome. The prevalence increases with age. You can see that women are twice as likely to be affected than men.
The eye is bathed in tears for a number of reasons. The tears help keep the delicate tissues on the surface from drying out and becoming irritated. The tears themselves contain antibacterial enzymes to protect from infections, and protect the eye from dust and dirt. A smooth, wet ocular surface allows for clearer vision since the cornea is more transparent when it’s wet.
The tear film covering the eye is actually made up of three distinct layers:
1) Mucin layer, produced by the conjunctiva (the clear membrane that covers the whites of the eye;
2) Watery layer, produced by glands in the eyelid and by the lacrimal gland in the outer corner of each eye; and
3) Oily layer, produced by meibomian glands in the eyelids. This outermost layer protects the other two and keeps the tears from evaporating.
Dry eyes can be caused by an abnormality of any of these three layers. Often, people have a problem of more than one of these layers, so you’ll see that the treatments noted below are directed at the specific underlying cause. Dry eyes can be caused by temporary, self limited conditions or more chronic diseases.
Regarding the mucin layer, the goblet cells of the conjunctiva may be temporarily damaged following acute inflammation, such as conjunctivitis (pinkeye), allergy, or chemical exposure from something splashing in the eyes. After the irritation resolves, the eyes may still feel dry for a few weeks until they recover. The conjunctiva may also be permanently damaged from chronic infections, autoimmune diseases, reactions to medications or injury.
The next layer – the watery layer of the tears – may also be adversely affected by numerous conditions. Hormonal changes associated with aging and menopause decrease tear production. Thyroid conditions, and certain medications such as antihistamines, beta blockers, diuretics and anti-depressants may result in fewer tears. Chronic inflammation of the lacrimal glands due to autoimmune diseases such as rheumatoid arthritis or Sjogren’s syndrome can cause dry eye.
The outermost layer of the tears prevents the tears from evaporating. The oil-producing meibomian glands are lined up in rows, and empty through small pores in the eyelid “rim”. Abnormalities of these glands are called “blepharitis” and may be caused by acne, seborrhea, allergy, chronic eyelid infections, or hormone variations. Blepharitis may also lead to styes or chalazia, which are infections or cysts in the eyelids.
Did you know that dry eye is the most common cause of tearing? That’s because in addition to producing a baseline level of tears all the time to keep the eye lubricated, there is a reflex by the lacrimal gland to produce tears quickly when the eyes are irritated. This helps to flush them out and protect them if something gets in them, or wind, smoke, or fumes bother them. A dry eye will also cause the same reflex!
Dry eyes are usually diagnosed by the history and the clinical exam. I am often asked by patients, “do my eyes look dry”? Frequently, the answer is no, but that doesn’t mean they’re not dry! When there are no objective findings, we’re glad because that means there has been no damage. Most cases of dry eye are uncomfortable and irritating but not dangerous. However, severe dry eye can cause vision loss. We look for redness, uptake by special dyes placed in the eye, rapid evaporation of the tears, “punctate erosions” or pits on the surface of the eye, abnormal blood vessels, and scarring. Sometimes we’ll perform a Schirmer’s test, in which tiny paper rulers are placed in the lower eyelid and tear production is measured. We also check for any problems with the eyelid position as sometimes an incomplete blink from Bell’s palsy or abnormal eyelid position will cause the eye to be exposed and dry. We check to see if the eye is bulging out from a tumor or thyroid disease, which may keep the eyelids from protecting it properly.
If your eye doctor determines that the cause of your symptoms is dry eye, the treatment will depend on the cause and the severity. Most often we start with nonprescription artificial tears. These can be used as often as necessary. There are many brands, but they should specify “lubricant eye drops”. The differences among them is in the extra ingredients which are purported to stabilize the tears. Try different ones to see what works for you, but avoid drops that are for allergy or “get the red out” because those can have a drying effect. If the redness is due to dryness, then just artificial tears alone will help. Some people use the artificial tears only as needed, but for frequent dry eye symptoms I recommend using the drops on a regular basis: breakfast, lunch, and dinner, or on some other schedule you’ll remember!
Protecting the eyes and avoiding exacerbating conditions is important. Avoiding smoke, fumes, dirt and dust, and wearing eye protection when you need to be in those environments is important. When we stare at a computer or concentrate intensely, we blink less often and our eyes dry out. Taking a break every fifteen minutes or so for a minute or two, remembering to blink, or putting in artificial tears will help symptoms.
Blepharitis is treated with hot moist towels applied to the closed eyelids for 5 minutes several times a day, but most importantly at bedtime. This helps to “melt” the solidified oil in the oil glands of the eyelid. Then gently massage your eyelids right at the level of the eyelashes, and this helps to express the oil. Often this technique, in addition to artificial tears, brings much relief within a few weeks. Sometimes we’ll add antibiotic eyedrops or ointment, antibiotic pills if associated with acne rosacea, and short term topical steroids. A recent study reported in the journal Ophthalmology demonstrated that oral consumption of omega-3 fatty acids (180 mg EPA and 120 mg DHA twice daily for 30 days) is associated with an improvement in dry eye symptoms.
If artificial tears, hot compresses, eye protection and blinking don’t improve symptoms, we might consider punctual plugs. These are tiny silicone plugs that are placed in the puncta (tear ducts) located in the inner corner of each upper and lower eyelid. These allow the tears that you do make to drain more slowly and keep the eye wetter longer. A prescription eyedrop, Restasis (cyclosporine A) is used as a treatment for chronic dry eye and works by decreasing inflammation and increasing natural tear production. Restasis takes some time to have an effect and must be used twice a day regularly and long term to sustain its benefits, and often is used in conjunction with artificial tears and punctual plugs.
Although dry eye is often a chronic condition, the symptoms can be decreased with appropriate therapy. Work with your eye doctor to alleviate the discomfort and irritation, especially now that winter is coming and the heat is on, adding to the dry conditions!
eye drop photo © 2013 American Academy of Ophthalmology