Moisture chamber glasses are an old and often overlooked idea for relief in moderate to severe dry eye. They are mentioned in the DEWS report as being an evidence based treatment strategy. So I am doing a special feature on them here at Dr Wet.
So I have started with most basic type of moisture chamber goggle – the swimming goggle. Cheap and readily available here in Perth. I set up a test to record their effectiveness.
The basic set up was to find out how much they could increase my tear break up time. Normally we measure this by instilling fluroscein (that is the orange dye) then we look under high magnification with a blue light to see how long the tear film stays intact before it breaks down. This is called the tear break up time. In a normal person this would be over 10 seconds, moderate dry eye around 5 seconds and in severe dry eye 1 or 2 seconds. When the tear film breaks down 2 things happen: firstly the vision goes filmy this is because you need a nice smooth intact tear film in order to see clearly. The second thing that happens it that it hurts! When bare cornea is exposed to the air there is a significant sensation of burning and stinging.
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This stinging burning sensation is the basis of another way of measuring tear break up. It is called the non invasive break up time (NIBUT). This test works for about 70% of dry eye sufferers who still have normal sensation in their cornea. There is a small group who’s corneas have adapted to their condition by becoming somewhat numb. We call these people “ damagers”. Their corneas are all scratched up and yet they don’t feel a thing.
You could work out your non invasive break up time ( assuming you are not a damager) right now. All you have to do is blink and start counting .. one thousand and one, one thousand and two, one thousand and three etc… when your vision first starts to go filmy and your eyes start to burn so that you have to blink. That is your non invasive break up time.
So here is my set up. On a chilly Perth morning I am in my study with the fan heater blowing hot air on me – pretty challenging environment. Best of four and I average 8 seconds non invasive break up time, which is not bad. Then on go the swimming goggles with a few drops of water in them. Over time this creates a very humid environment. Within 5 mins the goggles have all steamed up and my break up time is now 22 seconds, by 10 mins there are drops of water forming on the inside of the goggles and I can hardly see a thing but my break up time is 38 seconds. I take off the goggles and 5 mins later my break up is back to 7 seconds.
This demonstrates very well the role of humidity and evaporative stress on the break up of the tear film. In fact this goggle test is one way to determine if person symptoms are due to dry eye or corneal neuralgia. There are some who complain of the symptoms of dry eye and yet their eyes look pretty normal. No amount to drops or any other dry eye treatment helps the situation. So if you wear goggles as described and your don’t start to feel even a little better then it is a clue the problem isn’t dry eye.
So my next step is to order some moisture chamber goggles when they arrive I am going to repeat the test. I have a look online and these look like a good place to start. For a start they look reasonable. They could be worn in an office environment and certainly at home. They can also fit prescription lenses.
So I’ll report back when they arrive. If you want to make sure you don’t miss the update then sign up for our news letter.