what is dry eye?
If you have dry eye — also called dry eye disease or dry eye syndrome — it means something has gone wrong with some part of your tear system or tear film, resulting in compromised eye comfort, eye health, and/or vision.
The tear film, when healthy, is an amazing fluid that normally coats the surface of your eyes and the insides of your eyelids, helping to ensure your eyes are always comfortable and protected and your vision is stable and clear. But suppose something in the system breaks down. The water-producing lacrimal glands are damaged or diseased and don't produce enough water. Or the oil-producing meibomian glands are inflamed and not secreting enough oil to keep your tears from evaporating. Or the goblet cells are depleted, not generating enough mucous to anchor the tears to the eye surface. Or the eyelids aren't closing completely and your tears are evaporating faster than they can be replaced. What happens?
Without healthy, plenteous tears your eyes become uncomfortable and you may have blurry or fluctuating vision, among other things.
For patients, the experience of dry eye tends to be all about sensation. Contact lens discomfort, gritty, irritated or light sensitive eyes send people to their eye doctor. In more severe cases, persistent burning sends them back frequently and goads them through a variety of treatments. The life impact of that burning sensation and other forms of discomfort on people with dry eye is often profound. Among many other things, it can, and did, turn a dry eye drug with a surprisingly low success rate into half-billion-a-year blockbuster.
Of course, nearly everyone occasionally experiences mild dry eye symptoms (irritated, scratchy, gritty or watery eyes) under certain circumstances. That is what people commonly understand the term to mean. But dry eye is a heterogeneous disease — that is, a catch-all term for many things — and traverses a wide spectrum of symptoms and severity. Even when it is not medically serious enough to affect the vision, dry eye can cause an extremity of constant discomfort with a profound impact on function and quality of life, understood only by those who suffer from it. Thus, dry eye is a convenient but medically inaccurate, misleading and in many cases trivializing term that we are stuck with.
If the idea that dry eye could be crippling sounds improbable to you, try holding your eyes open for 60 seconds. Then ask yourself what it might be like for your eyes to feel that way all day.
how prevalent is dry eye?
How many people get dry eye?
5 to 50% of people get dry eye, according to the most current and extensive review of existing research (See TFOS DEWS II Epidemiology report, Abstract).
Why such a wide range? Sounds crazy, doesn't it? It's complicated. Here are just a few of the reasons:
- There is no commonly accepted rule for how to measure it. Every study is different.
- There's a broad spectrum of severity and a lot of overlap with other conditions.
- Geography plays a role. For example, people living at high altitudes, in dry climates and in polluted cities are more subject to dry eye.
- Ethnicity plays a role. For example, Asians are considerably more subject to dry eye than non-Asians.
What are the risk factors for dry eye?
You are more likely to have dry eye if you:
- Are female
- Are older
- Use a computer
- Wear contacts
- Are Asian
- Have meibomian gland dysfunction
- Have Sjogrens syndrome, or a connective tissue disease
- Are frequently exposed to pollution, low humidity; sick building syndrome
- Use any of the following medications: antihistamines, antidepressants, anxiolytics, isotretinoin
There are many, many, MANY more things associated with dry eye ranging from thyroid disease to refractive surgery (e.g. LASIK, cataract surgery). These are just some of the most common and most thoroughly documented contributors.
Source: TFOS DEWS II Epidemiology Report
What are the symptoms of dry eye?
What is dry eye like from the patient's perspective?
Here are some of the most common sensations or experiences people with dry eye report. This list starts with those most likely to be experienced by people with mild dry eye and progresses towards those more likely to be experienced when dry eye is moderate or severe:
- Watery eyes
- Eyes that tire easily, especially when using a computer, watching TV or reading
- Contact lens discomfort or intolerance
- Eyes easily irritated by wind, fumes, smoke, fragrances, etc.
- Fluctuating vision
- Blurred vision, especially in the early morning or late in the day
- Scratchy or gritty feeling eyes
- Achiness or soreness
- Foreign body sensation (feeling of something in the eye, but nothing's there)
- Sensitivity to light
It is important to note that symptoms of dry eye can overlap with or even be confused with other conditions, such as ocular allergy, lagophthalmos (incomplete eyelid closure, resulting in too much tear evaporation) and even recurrent corneal erosions.
How is dry eye diagnosed?
A dry eye assessment, according to TFOS DEWS II Diagnostic Methodology Report, should include checking the following:
- Symptoms and visual disturbance (i.e. questionnaire for patient to complete)
- Tear film stability, e.g. tear break-up time
- Tear volume, e.g. tear meniscus or Schirmer test
- Tear film composition, e.g. osmolarity tets
- Damage to the ocular surface, e.g. ocular surface staining
- Inflammation of the ocular surface, e.g. redness; advanced testing methods
- Eyelid involvement, e.g. looking for specific conditions and checking to see if the lids are fully functioning and closing completely.
Your diagnosis should not just be "dry eye", which, coming from an optometrist or ophthalmologist, is about as specific as "heart disease" would be, coming from a cardiologist. Ask for details. Specifics matter. Do you have aqueous deficient dry eye (inadequate secretion of the watery part of the tears from the lacrimal glands)? Or evaporative dry eye (inadequate secretion of oil from the meibomian glands) and if so, why? And are the eyelids doing their job with complete blinks? and so on.
How is dry eye treated (medically)?
It is really important to remember that treatment should relate to your specific diagnosis (see section immediately above) — not just dry eye generally! This is a partial list of treatments that have been used for various types of dry eye:
- Supplement, trap or stimulate tears
- Artificial tears
- Biologic tears (autologous serum or others)
- Punctal occlusion (plugs, cautery)
- Secretagogues (topical or oral)
- Stimulation (e.g. TrueTear)
- Treatments for eyelid abnormalities
- Blepharitis treatments — lid hygiene, antibiotics, tea tree oil products
- Meibomian gland dysfunction treatments — compresses, expression, debridement, lipiflow, ipl, probing
- Treatments for corneal exposure
- Drops, gels, ointments
- Dry eye glasses, goggles, shields, tapes, films
- Bandage contacts
- Scleral lenses
- Anti-inflammatory drugs, e.g. steroids, cyclosporine (Restasis), tacrolimus, lifitegrast (Xiidra), lubricin; tetracyclines
- Surgeries (rare in dry eye, other than conjunctivochalasis surgery, tarsorrhaphy and other eyelid surgeries)
- Dietary modifications (hydration, essential fatty acids)
- Environmental modifications (addressing things like contact lens wear, blink rate, dry and/or polluted air, and topical and systemic medications that are drying)
- Complementary medicines (e.g. herbal treatments, acupuncture)
- Managing psychological aspects (yes, this is actually included in a proper treatment protocol)
Summarized from: TFOS DEWS II Management and Therapy
How is dry eye managed (practically)?
What practical measures and lifestyle changes do doctors recommend, or patients employ on their own, to care for their eyes and reduce the impact on their quality of life?
- Lubrication. Drops, gels and ointments are used not just to lubricate, but to keep the eyes comfortable. Plenty of people whose dryness is not clinically severe use drops frequently because their eyes are uncomfortable. Chilled drops can be extra soothing for some.
- Warm compresses. Compresses are often done for medical reasons (treating MGD), but many people do them for comfort as well.
- Cold compresses. These are helpful for pain and lid inflammation.
- Dry eye glasses, which control the micro-environment around the eyes and improve eye comfort.
- Goggles, shields, masks, tapes and films for protection while sleeping.
- Environmental controls: Humidifiers for home, office and even cars. Re-direction of all vents in home, office and car. These measures are particularly necessary in challenging climates — dry and/or high altitude, and during months when heating and air conditioning are drying out indoor air.
- Whole body hydration.
- Modifications to computer use such as lower screen positioning, justgetflux.com, and blink reminder software.
- Modifications to activities, where possible, such as avoiding excessive screen time.
What is the life impact of dry eye?
What are some of the practical challenges attending dry eye? They may include, among others:
- Difficulty getting a detailed, accurate diagnosis, which is a vital step for getting the most appropriate treatment.
- High out of pocket costs of treatments not covered by insurance as well as over-the-counter lubricant needs.
- Pain management, for those with severe symptoms.
- Driving can be difficult without fully sealed moisture chambers.
- Outdoor activities may be greatly restricted, though this can usually be mitigated with well-fitting moisture chamber sunglasses.
- Workplace challenges, from low humidity, inconveniently placed vents and poor air quality.
- Depression and anxiety are very common when dry eye symptoms are severe and persistent (even if the condition isn't considered to be clinically serious).
- Difficulties keeping our doctors thoughtfully engaged in the process of finding solutions for us. We dry eye patients tend to be considered a bit of a nuisance because (a) we are chronically unhappy, and (b) we take a lot of chair time, and (c) we don't produce much revenue, and (d) we aren't easy to figure out or fix and (e) we often describe symptoms that do not seem to match clinical test results. In other words, we're not fun or satisfying to deal with. There is a growing number of exceptional specialists paying attention to our plight, but they are still a small minority.