Ceri Smith-Jaynes, optometrist and Optometry Today ’s Clinical Multimedia Editor, explains the paradoxical world of dry eye
“My eyes water a lot”, says my patient. Yet, the Christmas adverts aren’t on any more and the latest Attenborough series has finished. In fact, their ‘watery’ symptoms are probably because this person has a condition called dry eye. I now need to work out how I explain this without sounding like a complete idiot who hasn’t listened to a word they’ve said.
Why dry eyes water
There are many words people use to describe their symptoms of dry eye but ‘dry’ is rarely one of them. Hot, tired, gritty, achy, blurry, itchy and watery are, with symptoms usually worsening during concentrated tasks such as reading, driving or staring at a screen.
Most dry eye is caused by the eye’s thin coating of tears evaporating before you blink. If your tears evaporate quicker than normal, your eyes get dry; if you blink less than normal, your eyes get dry. When concentrating, you blink much less, so the tears dry up and the eyelid scrapes over the desiccated surface instead of aquaplaning on a smooth film of tears. Just watch someone having a chat and count how many times they blink in a minute. Now count again as they turn back to their computer screen or phone. (Best not to let them see you staring at them; your explanation will be implausible at best).
As the tears evaporate, they become more concentrated and salty. This causes inflammation of the eye and the lids, so the eye gets hotter. The heat evaporates the tears more quickly and they become even more salty, and so the vicious circle of dry eye develops. Often the eyes will respond to dryness by flooding with tears to get wet again, hence the dry eye/watery eye paradox.
Your environment also matters. If you’re running a dehumidifier or a gas fire in the house, you’re likely to get dry eyes. Alternatively, if you’ve covered the radiators in wet washing whilst watering your tropical houseplants, your eyes won’t get as dry. If you’re spending the long winter nights playing a first-person shooter video game in six-hour bursts, you’ll get dry eyes.
Luckily there are easy things you can do to relieve symptoms:
- Blink more, especially during screen time
- Make your home or office more humid
- Drink plenty of water and eat foods rich in omega 3, such as oily fish
- Visit your optometrist who can recommend the right eye drops and investigate any underlying medical causes
Ceri Smith-Jaynes is OT’s Multimedia Clinical Editor and is an optometrist in independent practice in Lancashire