Contact Lenses

What is the contact lens?

Contact lenses are prostheses that can be placed on the outer surface of the eye, such as the cornea and sclera, and can be used for correcting or treating refractive errors.


What are contact lens types?


Development of contact lenses; Some sources refer to contact lenses dating back to the Renaissance, but the first definition belonged to British astronomer John Frederick William Herschell in 1845. The first contact lens was made by Xavier Galezowski in 1886 to facilitate wound healing after cataract surgery. The first contact lens for keratoconus patients was produced by Eugene Kalt in France in 1888. Significant developments in lens design were made by the Hungarians under the leadership of Joseph Dallos in the 1930s. Until the 1930s, the only material used for contact lenses was glass, but from that date a plexiglass, polymethylmethacrylate (PMMA), a very lightweight material compared to cama, entered this area and allowed the lens to stay on the cornea only. In the same year, the first rigid gas permeable lenses, Celluloid (cellulose acetate butyrad) lenses, were used for the first time. The beginning of the modern lens age is considered to be the use of the corneal lens of the name Solexlens by PM Kevin Tuohy in 1948 in humans. The 1950s were the beginning of a very important process with the introduction of hydrogel lenses (including water) made of polymerized hydroxyethylmethacrylate (HEMA). This first soft lens was produced in Prague by Otto Wichterle, Daroslav Lim and Maximillian Dreifus. The spin-cast machine, which allows the mass production of these lenses, was again the invention of Wichterle in 1966. In the 1970s, a significant development in rigid lenses has been made of rigid gas-permeable lenses (RGP), CAB, Silicone acrylate, and then fluorocarbon materials that can replace oxygen instead of oxygen-free PMMA material. At the beginning of the 1990s, soft lens production technology changed, and the introduction of the copying system and the use of planned monthly change lenses. Since 1996, fluorosilicone hydrogel contact lenses have increased the oxygen permeability of soft contact lenses and lenses become available at night.


For what purposes are contact lenses used?

1. Correction of the most frequent crushing defects. For this purpose, their use is an alternative to the use of glasses and the elimination of fracture defects by surgical methods and laser. Refractive errors that can be corrected by contact lens; Myopia is hyperpigmentation, hypermetropia is astigmatism, and presbiopia is the loss of sight near age. Of these 4 problems, the contact lens can provide a complete correction in the first three, while the latter is of limited utility. In addition, contact lenses are also used to provide vision for patients who have lost lens organs due to aphasic name, cataract or trauma but can not be surgically implanted with an intraocular lens, especially for infants. Another area of ??use is anisometropia. This means that there is a significant difference between the fracture defects of both eyes. The use of glasses is very problematic or impossible in patients with two or more different refractive errors between two eyes. In these patients, the problem is solved with the contact lens.


2. Cosmetic use: They are used to change eye color or to provide aesthetic appearance in patients without iris layer.


3. Therapeutic contact lens use: In many eye surface diseases, contact lenses are used to accelerate the healing period. In addition, hard lenses are used to increase visual acuity and slow the progression of the disease in keratoconus disease, a progressive disease of the cornea from its youth.


What problems can be encountered with contact lenses?

There are also great hesitations about contact lenses today. However, 80 million people in the world are still using contact lenses. The use of contact lenses in developed countries is very high. However, it is very important for users to know the problems with contact lenses. The main ones of these problems are summarized below;


Corneal infection:

It is the most important contact lens complication. Nowadays, monthly excretion has become a very rare problem by increasing the penetration of the lenses and increasing the oxygen permeability of the lenses. Reasons; 1) Incorrect lens maintenance and use of lens. (It is extremely important that the solutions used for this purpose are recommended by the Eye Doctor.) 2) Overuse of lenses that are not oxygen permeable at night (this is the most frequent reason) 3) More use of monthly change lenses over time 4) Eye conjunctivitis,