Dry eyes and dry eye problems are a very common eye condition that can affect eye health and vision. Dry eye is a chronic condition in which there is an insufficient quantity or unhealthy quality of tears to lubricate and nourish the eye. Dry eye often goes undiagnosed and untreated, despite being a very common and treatable disease. As the population ages, its prevalence is also increasing. Currently between 20 and 25 million Americans suffer from dry eyes. Women are more prone to suffer from dry eye disease. This includes 3.2 million women over the age of 50 and 15% of all Americans over age 65.
What is the Tear Film?
When you blink, a film of tears spreads over the eye, making the surface of the eye smooth and clear. Without this tear film, good vision is not possible. The tear film consists of three layers, each with its own purpose:
- An Oily Layer
- A Watery Layer
- A Mucus Layer
The oily layer, produced by the Meibomian Glands in the eyelids, forms the outermost surface of the tear film. Its main purpose is to smooth the tear surface and reduce evaporation of tears.
The middle watery layer makes up most of what we ordinarily think of as tears. This layer, produced by the lacrimal glands in the eyelids, cleanses the eye and washes away foreign particles or irritants. The inner layer consists of mucus produced by the conjunctiva. Mucus allows the watery layer to spread evenly over the surface of the eye and helps the eye remain moist. Without mucus, tears would not stick to the eye. Anytime you do not produce enough tears, or if tears evaporate or drain too quickly, the symptoms of dry eyes may become present.
What are the Symptoms of Dry Eyes?
The symptoms of dry eyes include a scratchy, dry, sandy or gritty feeling that can be accompanied by a stringy, clear, white discharge with noticeable pain and redness. Dry eye creates additional risk of corneal infection, as the tear film, which serves as a protective mechanism and contains a number of antimicrobial components, is deficient. The most common dry eye symptoms include:
- Stinging or burning eyes
- Grittiness or scratchiness
- Stringy mucus in or around the eyes
- Discomfort when wearing contact lenses
- Blurred or Fluctuating Vision
- Pain
- Light Sensitivity
- Tired Eyes
- A feeling of a foreign body or sand in the eye
- Excess tearing
- Redness of the eye
- Heavy eyelids
- Increased eye irritation from smoke or wind
- Decreased tolerance of reading, working on the computer, or any activity that requires sustained visual attention
Visual tasks can cause excessive evaporation of tears from reduced blinking. These tasks include prolonged periods of reading or computer use. Excess tearing from “dry eye” may sound illogical, but it can be understood as the eye’s response to discomfort. If the tears responsible for maintaining lubrication do not keep the eye wet enough, the eye becomes irritated. Eye irritation prompts the gland that makes tears (called the lacrimal gland) to release a large volume of tears, overwhelming the tear drainage system. These excess tears then overflow from your eye.
Excessive Evaporation of Tears
There are a number of factors that can cause an excessive evaporation of your tears such as exposure to forced hot air heat at home or at work, dry climate in general, air travel, reduced blinking from contact lens wear, reduced blinking from looking at a computer screen or reading for long periods of time, air pollution or even just blowing your hair dry. Your tears may evaporate too quickly if you suffer from low-grade eyelid inflammation, called Blepharitis. Within your eyelids are tiny tubular glands called Meibomian Glands. Inflammation of the eyelids, from Blepharitis, or a condition called Rosacea can cause the Meibomian Glands to stop functioning properly and decrease the production of the secreting their oily film.
About Meibomian Gland Dysfunction (MGD)
Meibomian Gland Dysfunction (MGD) is a common cause of dry eye as without the oily layer being present it is very likely tears will evaporate too quickly. This is an especially common problem for perimenopausal women, as it is believed that 75% of women in this age group have some presence of facial rosacea. This, along with the general hormonal changes occurring during this time, makes perimenopausal woman particularly susceptible to dry eyes. Further, your tear film may evaporate too quickly if the tears are not properly spread and replenished over the surface of the eye because of poor eyelid movement. This may be due to a number of factors including:
- Improper or incomplete closure of your eyes during sleep
- Eye “bulging” conditions that may be related to thyroid problems
- Loss of tone or shape of the eyelids so that they turn in or turn out, called entropion and ectropion.