RGP contact lenses are designed for extended wear. Put an RGP lens in and you can leave it there – overnight, all week and even, is some cases, for a full month – without worrying about irritation or an increased risk of developing eye infections. They’re also custom made to fit your eye.
R.G.P. stands for Rigid Gas Permeable. RGP lenses are rigid because they are made to be reworn. They’re stiffer than the soft lenses people generally refer to when they talk about ‘contacts’, so they won’t tear easily and are excellent at correcting astigmatism, an optical defect caused by a cornea or lens that isn’t spherical. It most often leads to blurry vision – an irregularly shaped eye can’t bring a single point into sharp focus – but astigmatism also triggers headaches and, in some cases, chronic fatigue. RGP lenses are so good at correcting the condition precisely because they’re rigid. While you’re wearing them, your cornea and lens are pressed into the right shape and held there.
RGP lenses are gas permeable because your eyes need to breath. They’re narrower than ordinary contacts and made of materials that are highly oxygen permeable (RGP lenses are also called oxygen permeable lenses), so your eyes function normally while you’re wearing them. In the past, lenses intended for continuous wear increased the possibility of contracting an eye infection. Sometimes – after long periods of continuous use – they also led to acute irritation. The reason was simple: the organisms that irritate and cause infections thrive in warm, moist environments, exactly like the environment underneath a contact lens. To fight these organisms, your body would normally increase the oxygen supply to the affected area, in this case the cornea, but the lenses made this impossible. Peoples’ eyes were literally suffocating, and doctors eventually decided that no contact should be worn overnight – until RGP lenses came along.
Today, laser eye surgery (or LASIK, to those in the know) is often prescribed for astigmatism. And with good reason: LASIK is a low risk, permanent solution. It can give you 20/20 vision in the course of a short, painless procedure – but it isn’t for everyone. Some people are not good candidates for LASIK: you might be younger than 18 or have a condition that makes LASIK impossible. Others just can’t swallow the idea of surgery, however uninvasive, on their eyes. The choice is personal, but worth making because, either way, you’ll once again have perfect vision from the moment you open your eyes in the morning, until the moment you close them at night.
Peter V Anderson is an ophthalmologist based in Shanghai. His articles are intended for reference purposes only, and a qualified eye care specialist should be consulted before you make any decisions that might affect your eye health.