Glasses have two major functions: vision correction and eye protection.
For vision correction, we have glasses for nearsightedness, farsightedness and astigmatism. For presbyopia people, we have bifocal glasses. Recently Oxford University professor Joshua Silver invented a self-adjustable glasses using silicon oil in a thin plastic reservoir as lenses. This invention brings new hope for the poor people in the world to see the clearer world.
There are many types of glasses which are for protection purpose. Sunglasses are the most typical glasses for protecting eyes from UV rays and strong lights. Sports glasses like basketball glasses and ski goggles are two basic ones. Basketball glasses prevent sports participants from being injured. These glasses can also be worn in other sports events such as football, volleyball, tennis and safari activities. Ski goggles prevent eyes from the extensive harm of UV rays reflected by the snow and possible injuries caused by bumping.
In industrial world, there are some special glasses for field protection. For example welders need to wear special shield to prevent exposure to extra strong arc.
Modern technology brings us a brand new invisible “glasses” called contact lenses. Contact lenses free people from the inconveniences of wearing spectacles and return the natural facial beauty to the wearers.