By Steve Roberts 

Ortho-k lenses  which are only worn while sleeping can be the perfect solution to one of winter's perennial problems for glasses wearers - having their glasses steam up as they move from indoors to outdoors or vice versa on a cold day. Essilor - a major spectacle lens manufacturer - recently carried out a survey which revealed that 4 in 5 spectacle wearers find fogged lenses a problem when moving between indoor and outdoor temperatures. This frustrating phenomenon happens because the lenses are warmer or colder than the air they encounter thus leading to condensation on the surface. The fogged-up lenses which result can also be fraught with danger as a sudden loss of vision can lead to falls or collisions - especially on the kinds of slippery surfaces that are encountered on winter days.

Whilst companies like Essilor have striven to develop new designs of spectacle lenses which can deal with this type of condensation problem, the solution can prove expensive for glasses wearer given the typically high costs of the lenses. Other solutions such as chemical sprays need to be applied continuously to ensure that the condensation problem is minimised. So it is good news for short-sighted glasses wearers to know that ortho-k lenses avoid this problem completely. These small, custom-designed contact lenses are only worn at night and correct short-sight by gently flattening the surface of the cornea to ensure light will focus directly on the retina rather than in front of it.

The correction effect of ortho-k lenses  lasts for more than 24 hours after they are removed each morning so that the wearer enjoys perfect lens-free daytime vision until the lenses are reinserted at night before going to bed. This unique new treatment for shortsightedness offers all the benefits of laser surgery but without the surgery and is particularly attractive for people who play sports or those daytime contact lens wearers who suffer from dry and irritated eyes due to working in air-conditioned environments - especially if this involves staring at computer screens for extended periods. So for glasses wearers, you can forget about fogged-up glasses - indeed, you can forget about glasses completely - by switching to ortho-k lenses .

Check if you are suitable for overnight ortho-k corrective contact lenses .