What is a Contact Lens
A contact lens is a medical device and can be worn to correct vision, as well as for cosmetic or therapeutic reasons. Nowadays contact lens can be either corrective or non -corrective in nature depending on the usage of the lens. A cosmetic or colour contact lens without any prescriptive power or non-corrective contact lenses are used to change the look or colour of a user’s eyes. Unlike corrective contact lenses, they do not correct vision. To date cosmetic or colour contact lenses can be corrective or non-corrective in function. Both corrective and non-corrective contact lens are regulated as medical devices by the Medical Device Authority (MDA). According to the Medical Device (Declaration) Order 2017. All contact lenses, even purely cosmetic ones, require a prescription. They must be properly fitted and prescribed by a Licensed Eye Care Professional.
TYPES OF CONTACT LENSES
Daily Disposables Contact Lens
Daily disposable contact lenses are single-use lenses that are removed and discarded at the end of each day, and a fresh pair of lenses is applied to the eyes the next morning.
Monthly Disposable Contact Lenses
Monthly disposable contact lenses are contact lenses that can be worn daily for up to a month or 30 days. Unlike daily disposable lenses, the monthly disposable contact lenses are reusable, and after each day usage, you are to clean, disinfect and store them in fresh contact lens-care solution till next day for wearing again. Monthly disposable contact lenses are normally long-lasting and more durable.
Coloured Contact Lenses
Coloured contact lenses are designed to mimic the appearance of the iris or the coloured part of the eye. The iris is a blend of different coloured lines and shapes, so in order to capture a likeness, coloured contact lenses are created using dots and lines for a natural look. Coloured contact lenses can be referred to as cosmetic contact lenses whereby the wearer can change their eye colour for everyday wear or special occasions. Coloured contact lenses can come in the form of non-prescription (plano) or with prescriptive power.
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By definition, a custom-made contact lens is any soft, gas permeable (GP) or hybrid lens design that is specially made to order, with multiple design parameters that can be manipulated. Most of these custom-made contact lenses are indicated for hard to fit eyes. Other lens designs also are available — including lenses fabricated for use in special situations, such as correcting for keratoconus. Custom-made contact lenses often are designed to be worn for much longer period (a year) as compare to frequent replacement contact lenses. This makes proper daily lens care even more important to keep the lenses clean and comfortable.
Rigid Gas Permeable (RGP) & Hard Contact Lenses
Rigid gas permeable (RGP) contact lenses are made from a firm, oxygen-permeable polymers material. A Rigid Gas Permeable contact lens is able to cover the natural shape of the cornea with a new refracting surface. This means that a spherical RGP contact lens can correct corneal astigmatism. RGP contact lenses can also be made as a front-toric, back-toric, or bi toric. RGP lenses can also correct corneas with irregular geometries, such as those with keratoconus or post-surgical ectasias. In most cases, patients with keratoconus see better through RGP lenses than through glasses. RGP lenses are more chemically inert, allowing them to be worn in more challenging environments than soft lenses.
Soft Contact Lenses
Soft contact lenses are made of soft, flexible plastics. The flexible plastic is combined with water to allow oxygen to pass through the contact lens to the cornea. This increases comfort and maintains eye health. Soft contact lenses may be easier to adjust to and are more comfortable than rigid gas permeable lenses. The soft flexible plastic material or hydrogel rely on their water content to transmit oxygen through the lens to the cornea. Higher water content lenses will allow more oxygen to the cornea. The latest silicon hydrogel contact lenses have extremely high oxygen permeability characteristics that they are even approved for overnight wear (extended wear). Current brands of soft contact lenses are either traditional hydrogel or silicone hydrogel. Because of drastic differences in oxygen permeability, replacement schedule and other design characteristics, it is very important to follow the instructions of the eyecare professional on prescribing contact lenses.
