Dry eye occurs when the eye doesn’t make sufficient tears or when tears evaporate too quickly. It’s estimated that around 30 per cent of Canadians experience ocular symptoms associated with dry eye. These symptoms include stinging or burning eyes, scratchiness, pain, or redness. Strangely enough, one of the symptoms of dry eye may be an excessive production of tears such that a patient with dry eye may have tears rolling down their face.
What causes dry dye?
The ocular surface is covered by a thin film called the tearfilm that provides lubrication to the external part of the eye and facilitates blinking. When the eye surface dries, dry spots appear within the tearfilm, exposing the nerves of the cornea to the motion of the eyelid during blinking thus causing an irritating sensation. It’s estimated that over the course of the day, we blink more than 11,500 times. For people with dry eye, each blink can be irritating and even painful.
There are many causes of dry eye that may be classified as follows:
- Environmental: The dry air in an overheated room in winter or an over-air-conditioned room in summer may be sufficient to cause dry eye symptoms. Smoky environments can also cause dryness symptoms.
- Medications: A large number of medications are associated with dry eye. These include systemic antihistamines for allergies, systemic decongestants for cold symptom relief, antidepressants, hormone replacement therapy, diuretics, some treatments for Parkinson’s disease, and some blood pressure lowering medications.
- Aging: As we age, there is a decrease in the quantity of tears we produce. This may lead to dry eye.
- Systemic disorders: Autoimmune conditions such as Sjögren’s syndrome, lupus, rheumatoid arthritis, and scleroderma may cause dry eye. Dry eye is also associated with other disorders such as diabetes, thyroid conditions, and vitamin A deficiency. Conditions such as Bell’s palsy and other forms of facial paralysis that prevent the eye from closing properly may also cause dry eye.
- Inflammatory skin and eyelid disorders: Rosacea (an inflammatory skin disease) and blepharitis (an infection/inflammation of the eyelid) may cause dry eye by affecting the production of the lipid layer of the tearfilm.
- Computer vision syndrome: When we focus on a computer screen, or a cell phone screen, for long periods, we generally do not blink as often as we should. As a result, the eye tends to dry out. Also, when we look at a computer screen, we are usually looking more or less horizontally, and, as a result, the eye surface is more exposed and may form dry spots, which can be quite irritating.
- Laser eye surgery: It has been shown that the sensitivity of the cornea may be decreased for up to six months following laser eye surgery. This loss of sensitivity can lead to a decrease in the blink reflex and thereby affect the ability of the eye to reconstruct the natural tearfilm. This may lead to continued irritation from the dry spots during this early post-laser surgery period.
- Gender: Dry eye is more prevalent among women, particularly older women. Symptoms may be particularly prevalent during pregnancy.
- Contact lenses: People who wear contact lenses tend to be more at risk for developing dry eye.
How is dry eye treated?
There is a wide range of treatments available for the control of dry eye symptoms. Not all treatments work for all people. You may need to try more than one before finding a treatment that works for you. Treatments for dry eye fall into a number of categories:
- Environmental dry eye: If your environment appears to be the cause of your dry eye, you should use a humidifier to add moisture to the air in winter and should be careful not to air condition the room excessively in summer. Make sure your workspace is not directly in front of an air conditioner vent.
- Computer vision syndrome: If working on the computer is drying your eyes out, here are a few things you can try to alleviate your dry eye symptoms:
- Raise your chair, or lower your screen. This will lower your eye lids and decrease the dryness associated with more open lids. It is recommended that the computer should be 15 to 20 degrees down from your eyes. (This may decrease any neck strain at the same time).
- Adjust the brightness of your computer screen to make it comfortable, usually about the same brightness level as the surrounding light.
- Increase the font size of your screen so that reading is more comfortable and the need to focus intensely is diminished.
- Change the font itself. Sans serif fonts tend to be more comfortable to read.
- Try the 20-20-20 rule. Every 20 minutes look at something 20 feet away for 20 seconds, and take breaks every hour or two from looking at your computer. Try closing or blinking your eyes every now and again.
- Omega-3 fatty acids: Omega-3 fatty acids have been shown to play a role in the treatment and prevention of dry eye; however, it isn’t known what effective dosages are for this essential nutrient. Omega-3 fatty acids can be found in oily fish such as mackerel, albacore tuna, sardines, anchovies and salmon. These nutrients are also available as supplements.
- Artificial tears: These eye drops, gels, or ointments may be purchased over the counter in pharmacies. Some of the formulations are preservative-free as some preservatives may cause the eye to dry out in some people who are particularly sensitive to preservatives. Artificial tears help lubricate the surface of the cornea and may be applied several times a day. People who wear contact lenses should be careful to make sure that the artificial tear they are using is recommended for use with contact lenses. Some of the preservatives used in artificial tear preparations can build up in the contact lens and can be damaging to the eye. It’s important to read the label to make sure that the product you’re selecting is recommended for use with contact lenses.
- Prescription eye drops: Depending on the extent and nature of your dry eye, your eye doctor may prescribe one of the following medications for its treatment:
- Corticosteroid eye drops: These medications are usually used if there is an inflammatory component to one’s dry eye. They’re usually used for a short time only.
- Cyclosporin eye drops: This medication is usually used for long-term treatment of dry eye. It can often take a substantial time (three months or more) before relief is experienced, but some patients may experience relief sooner.
- Lifitegrast eye drops: This medication, approved for sale in Canada in 2018, works by moderating any inflammation associated with dry eye.
- Punctal plugs (lacrimal occlusion): It’s possible to reduce the outflow of tears by blocking the tear ducts by which the tears leave the eye. These plugs, about the same size as a grain of rice, are placed in the punctum, the entry to the tear duct. They may be semi-permanent, made of silicon or similar material, or may be dissolvable, made of collagen. The semi-permanent punctal plugs may also be removed by an eye doctor if required. Punctal plugs are usually recommended when eye drops are no longer effective in controlling the symptoms of dry eye.
Dry eye symptoms can be merely irritating, or they can lead to subsequent eye infections. For this reason, it’s important to see an eye doctor if self-treatment by any of the methods suggested above doesn’t appear to be working and your symptoms are getting worse.