Contacts have come a long way since Adolf Fick invented the first scleral contact lenses in 1888. They were rigid, covered a large portion of the eye, and could not be worn for more than a few hours at a stretch. In 1949, a patent was made in the United States for the corneal lens, which could be worn for 16 hours.
Since then, a constant pursuit of comfort and effectiveness has attracted enormous R&D resources towards contact lens technology. For instance, CooperVision, the maker of clariti contact lenses, spent over USD 55 million in a single year alone for bettering lens design and manufacture.
It has resulted in soft lenses which are cheaper, fit better, and have a low adjustment period. Read on to learn more about these eye-opening miracles.
Why contact lenses?
Compared to glasses, contacts provide a wider range of vision as they sit right on top of your cornea. They are ideal for sports and other physical activities. They are unaffected by weather conditions and do not fog up as glasses do.
How do they work?
Contacts are essentially prescription lenses that sit on top of a thin film of tear over your cornea. They correct the refractive error in your eye by deflecting the incoming light appropriately. A spherical lens bends light evenly no matter its orientation. So, it functions just as well, even if it rotates around your cornea.
However, such rotation can be a problem for people who have astigmatism as they need a lens with a different focus along the horizontal and vertical axis. The toric soft lenses are meant to do precisely that. They can be slightly weighted at the bottom to keep them oriented in the right direction.
People with presbyopia need lenses with multiple focal lengths. It helps them focus on things at varying distances – near, intermediate, and far. Much like the progressive lenses in spectacles, multi-focus contacts have a gradual change in focal lengths. It allows the wearer better visual acuity over a greater range of distances.
What materials are used?
The first contacts that gained popularity were made of polymethyl methacrylate or PMMA. They were durable but impermeable to gas. Wearers would feel discomfort after a few hours, as their eyes were being deprived of oxygen.
By the 1970s, the invention of gas-permeable materials allowed lenses with higher breathability. The wearer could wear these rigid lenses for hours together with the slightest discomfort. However, a user would take weeks to adjust to it properly, and it was very rarely suitable for children.
As a result, by the late 1990s, lens makers started using silicone hydrogel for manufacturing soft, disposable lenses. The ‘hydro’ part of the material – basically water- transmits much more oxygen than rigid permeable lenses, making the soft lens incredibly light and comfortable. Some lenses are so ‘breathable’ that they can be worn even while sleeping.
Exposure to UV rays is the leading cause of corneal damage and age-related blindness in Australia. Contacts with UV blockers in them can prevent harmful UV rays from injuring your cornea. Doctors advise using sunglasses in conjunction with UV blocking lenses, as they protect your entire sclera, not just the cornea.
Manufacturers of contact lenses, like the clariti contact lenses, understand that disposable lenses generate vast amounts of plastic waste. They offset it by facilitating plastic collectors in coastal towns to collect ocean-bound plastic and prevent it from reaching the sea. For every lens they manufacture, they ensure that the same amount of plastic is prevented from polluting the marine ecosystem.
Contact lenses have come a great way and are now affordable, comfortable, and highly effective. They are safer and more hygienic than ever before. If you have vision problems, visit an optometrist and get guidance on the right pair of contacts for you!