What can you do about uncomfortable eyes?
As the population ages, there are more and more men and women with dry eyes. About 10 percent of the population have dry eye, which tends to be more common in people with fair complexions, dry skin, or rosacea. Antihistamines, oral contraceptives and other medications also cause dry eye, as do environmental factors such as working in artificial climates and on computers. Most people with chronic eye irritation however, ultimately turn out to have either dry eye or blepharitis (eyelid inflammation).
Dry eye is caused by loss of water from the tear film with an increase in tear film osmolarity (salt content). Any condition that sufficiently decreases tear production, or increases tear evaporation, will result in dry eye.
- Tear production can be decreased by lacrimal gland disease, as seen in Sjögren’s syndrome, or by any condition that decreases corneal sensation (like LASIK laser eye surgery).
- Tear evaporation can increase as the palpebral fissure width (the distance between the
lower lid and upper lid) increases, or as tears lose their oil layer due to a dysfunction of
the oil glands in the eyelids. These oil glands are called meibomian glands, and the oil
they produce normally retards tear film evaporation, they gradually lose function with
age, or more rapidly from posterior blepharitis or meibomitis (inflammation of the
Increased tear film osmolarity, no matter what the cause, results in the following.
- Osmotically dehydrates the eye surface;
- Increases desquamation (peeling off) of the corneal and conjunctival epithelial cells;
- Containing conjunctival goblet cells. Conjunctival goblet cells are the mucous-producing cells on the eye surface that provide the natural lubrication for the eye;
- Decreases corneal glycogen levels; corneal glycogen is the energy source for corneal healing.
- The loss of ocular surface glycoproteins necessary for tear film stability.
Blepharitis can be divided into two major types:
- Anterior blepharitis is less common and is characterized by a dandruff-like process that occurs at the base of the lashes. (This is different from the crusting seen on the eyelashes in the still more uncommon type of anterior blepharitis caused by staphlococcal aureus).
- Posterior blepharitis is the most frequent type of blepharits and involves an inflammatory process centred around the meibomian glands; this inflammatory process can spread throughout the lid margin and spill over to involve the ocular surface as well. Ultimately inflammation involving the meibomian gland leads to scarring, causing increasing dysfunction of the meibomian glands.
The following factors help us decide on the cause of your discomfort:
- Character. What does the irritation feel like? Is it a sandy-gritty feeling, burning, foreign of the eyes? Do the eyes itch?
- Location. Where is the irritation located? Is it on the surface of the eye, in the eye, on the lid margin, or on the skin?
- Diurnal variation. Are the symptoms worse at any particular time of day? Patients typically have difficulty with this question. It helps to ask people what their symptoms are like upon awakening, at the breakfast table, at lunch and after dinner in the evening. Are they worse on awakening in the morning and then late in the day?
- Onset. Did the symptoms start suddenly, or did they develop gradually? Do symptoms occur in clearly delineated episodes or is this a continuous problem?
- Duration. How long have the symptoms been present?
- Aggravating factors. Wind, smoke, low humidity (i.e., airplane cabins), reading, watching TV, contact lens wear, artificial tears?
- Alleviating factors. Hot compresses, eye closure, high humidity, artificial tears?
Dry eye and posterior blepharitis are the two most common causes for chronic eye irritation. Dry eye is caused by loss of water from the tear film, resulting from either decreased tear production or increased tear film evaporation. The resultant increase in tear film osmolarity causes the changes on the eye surface responsible for the symptoms of dry eye. Posterior blepharitis causes eye irritation from inflammation, and leads to the development of meibomian gland dysfunction.
The primary goal of dry eye treatment is to help remediate the ocular surface and facilitate a more normal environment. The primary goal of meibomitis treatment is to reduce inflammation. This can be achieved by hot compresses and lid massage and, when necessary, systemic treatment. By determining the cause or causes of chronic eye irritation we can employ effective treatments to treat it; using eye drops inappropriately may make the condition worse in the long term – in spite of the short term relief they offer. When in doubt seek advice.