How Do Tears Work?
When you blink, a film of tears spreads over the eye. This keeps the eye’s surface smooth and clear. The tear film is important for good vision.
The tear film is made of three layers:
- An oily layer
- A watery layer
- A mucus layer
Each layer of the tear film serves a purpose.
The oily layer is the outside of the tear film. It makes the tear surface smooth and keeps tears from drying up too quickly. This layer is made in the eye’s meibomian glands.
The watery layer is the middle of the tear film. It makes up most of what we see as tears. This layer cleans the eye, washing away particles that do not belong in the eye. This layer comes from the lacrimal glands in the eyelids.
The mucus layer is the inner layer of the tear film. This helps spread the watery layer over the eye’s surface, keeping it moist. Without mucus, tears would not stick to the eye. Mucus is made in the conjunctiva. This is the clear tissue covering the white of your eye and inside your eyelids.
Normally, our eyes constantly make tears to stay moist. If our eyes are irritated, or we cry, our eyes make a lot of tears. But, sometimes the eyes don’t make enough tears or something affects one or more layers of the tear film. In those cases, we end up with dry eyes.
Dry Eye Symptoms:
- You feel like your eyes are stinging and burning.
- There is a scratchy or gritty feeling like something is in your eye.
- There are strings of mucus in or around your eyes.
- Your eyes are red or irritated. This is especially true when you are in the wind or near cigarette smoke.
- It is painful to wear contact lenses.
- You have lots of tears in your eyes. Having a lot of tears in your eyes with “dry eye” might sound odd. But your eyes make more tears when they are irritated by dry eye.
Dry Eye Causes
- People tend to make fewer tears as they get older due to hormonal changes. Both men and women can get dry eye. However, it is more common in women—especially those who have gone through menopause.
- Blepharitis (when eyelids are swollen or red)
- Entropion (when eyelids turn in); ectropion (eyelids turn outward)
- Being in smoke, wind or a very dry climate
- Looking at a computer screen for a long time, reading and other activities that reduce blinking
- Using contact lenses for a long time
- Diseases such as diabetes, rheumatoid arthritis, thyroid disease, parkinson’s and rosacea
- Taking certain medicines, such as:
1. Diuretics (water pills) for high blood pressure
2. Beta-blockers, for heart problems or high blood pressure
3. Allergy and cold medicines (antihistamines)
4. Sleeping pills
5. Anxiety and antidepressant medicines
6. Heartburn medicines
It is advisable to tell your ophthalmologist about all the prescription and non-prescription medicines you take.
Dry Eye Diagnosis and Treatment
It usually begins with a detailed eye exam. The eyelids, the surface of the eyes, as well as the blink rate is checked.
There are many different tests that help diagnose dry eye such as Ocular surface staining, TBUT, Schirmer’s, Meniscometry that measures the quality or the thickness of tears, how quickly you produce tears and how effectively they wet the eyes.
How Is Dry Eye Treated?
Artificial tear eye drops that are like your own tears. You can use artificial tears as often as you need to. If you use artificial tears more than six times a day or are allergic to preservatives, you should use preservative-free tears. This is because if the tears with preservatives are used a lot, these chemicals may start to irritate your eyes.
Punctal plugs (tiny silicone or gel plugs) can be inserted in your tear ducts to block them. This makes your natural tears stay in your eyes longer. These plugs can be removed later as needed. Punctal cautery can be done as a permanent solution.
Treating Dry Eye Culprits
Eyelid problems like MGD (Meibomian gland dysfunction) and Blepharitis can be treated with warm compresses on the eyes, massaging the eyelids, using eyelid cleaners like baby shampoo and night time ointments to decrease inflammation. Steroid eye drops are usually added to break the cycle of inflammation.
Omega-3 fatty acids can be added as a dietary supplement (pill or tablet). They are found naturally in oily fish (such as salmon, sardines, tuna, trout, and anchovies), and in flaxseeds.
Dry Eye Prevention Tips
- Try not to use a hair dryer, if possible. Avoid using facial cosmetics and hair dye as the vapors from them can further irritate the eyes.
- Stay away from very warm rooms. In the winter, add moisture to the air with a humidifier. Or put a pan of water near your heater or radiator.
- Protect your eyes from drying wind by wearing wrap-around glasses outside.
- 20-20-20 rule – For every hour of reading or watching TV, take a break and look away from the screen (at a distance of at least 20 feet) for at least 20 seconds and blink frequently (20 times/minute).
- Avoid cigarette smoke and alcohol.