Water Repellent Lenses for Glasses
Do You Need Water-Repellent Lenses?
You’re out and it starts drizzling. The rain-drops cover your glasses and you have to clean them - an annoyance you really don’t need!
Luckily, there are water-repellent coatings, also known as 'hydrophobic' coatings, which literally means fear of water, a very fitting name.
Switching to such lenses with a coating like Crizal can help avoid problems with water, rain, and sweat on our glasses, which can hinder our vision and be an irritation. You can see the same hydrophobic properties on the wings of different kinds of insects. A dragonfly can travel unhindered when it’s raining, as its wings are able to repel the water droplets with their hydrophobic coating.
What Are Water-Repellent Coatings?
Water-repellent coatings like Crizal prevents water droplets from sticking to the lens. This is achieved by adding a layer on at the top of the coating that allows water )and for that matter oil) to bead on the surface. The more the water beads the easier it is for drops to slide off the lens. This can be tested by placing a water drop on a lens sitting flat on a table and then titling it slowly until the water drop rolls off. The smaller the angle when the drop slides, the more effective the 'hydrophobic layer". The optimum angle is around six degrees. These lenses are ideal for people who wear their glasses all the time as it makes the lenses easy to clean and they stay clean longer.
How Does The Hydrophobic Coating Actually Work?
Imagine droplets of water running down a particular surface. When the surface is very "wettable", the droplets spread somewhat and stick to the surface. But then there are surfaces like on the lotus leaf which is rough, covered in tiny little protrusions, inhibiting the water droplets to join so run down and off the surface. This hydrophobic property create surface tension, and inhibit the surface from being covered, this is the same principle used on lenses, so water is repelled.
When Would I Need Water-Repellent Lenses?
Water-repellent lenses are useful for everyone who wears glasses:
- If you work outside or perform outdoor activities that would increase your chances of being in the rain
- If you’re an athlete and sweat sticks to your glasses and blurs your vision
- but most of all this type of coating make lenses easier to clean and keep clean
To find out how to get a lenses that are water repellent, visit your nearest optometrist.
Annoyed by the water droplets on your glasses?
Talk to an optometrist and learn more about water repellent lenses today