Contact lenses Dr. Nir Erdinast
Contact lenses are acrylic raw material found on the surface of the eye when contact lenses are the tears and corneal surface and soft contact lenses and are supported on the conjunctiva.
Contact lenses that the cornea and conjunctiva
Sklrliot contact lenses are large contact lenses that support the sclera (and hence scale)
Contact lens solutions
Contact lenses provide excellent cosmetic solution (without glasses) and optical correction and excellent quality to a wide range of refractive disorders (several glasses). Contrary to what people think, there are many types of contact lenses, different designs, different raw materials including soft contact lenses, contact lenses and contact lens Sklrliot.
Distribution of contact lenses
Contact lenses are divided according to the optical patch they give; According to the materials of which they are made; And the duration of use. Sometimes contact lenses provide optical correction glasses are preferable, especially in situations of high astigmatism, Anaizomtrofih, horizons and corneal disease conditions such as keratoconus and certain types of corneal scars or deformities. Nevertheless, improper use which could lead to a series of side effects and complications.
There are many types of contact lenses. They are divided according to the optical patch they give (one-bifocal lenses, multi-bifocal lenses, lenses hoes); According to their Ksihotn (soft or hard lenses); And the duration of their use (daily, bi-weekly, monthly, regular).
Types of contact lenses according to the optical Amendment
Soft contact lenses and severely classified according to the optical patch they give three main categories. This distribution is equivalent to glass lenses, but because of the contact lens in the eye is constantly in motion (rotation, blink, and the effect of gravity) contact lens design more complex.
1. Single bifocal contact lenses
Contact lenses are the most common and simplest design cost. These contact lenses can be crafted books (pellets) or a school (non-spherical) with a flat structure gradually approaching ranked as far as the scope of the lens. Every single bifocal contact lenses are with a single optical focus (usually distance or near). Most lenses are sold to consumers are contact lenses myopia (minus lenses) and therefore the range of numbers of these lenses range than contact lenses of farsightedness (plus contact lenses).
2. The serial contact lenses for astigmatism
Almost half (47%) of the components of the soft contact lens itself has astigmatism greater than or equal to 0.75 diopters at least one eye. Today there are a variety of options are available to fit contact lenses for patients Astigmtiim. Serial contact lenses are now available in a variety of raw materials, assembly and modes of paging frequencies. Serial contact lenses can find all kinds of raw materials: hydrogel, and silicone hydrogel contact lenses gas permeable (RGP). If the source is corneal astigmatism (astigmatism Kornialit), contact lenses directories are a great option. These contact lenses provide visual quality is very good and relatively easy to fit, but they are less comfortable soft contact lenses. In cases of high astigmatism Kornialit adjustment of contact lenses may be unstable. Other options to consider are hybrid contact lenses, contact lenses with a larger diameter, and in exceptional cases, contact lenses Sklrliot difficult. All an option for astigmatism contact lenses Kornialit high.
Serial soft contact lenses very diverse and have many stabilization methods. Truncated stabilization method is the first method that is used to stabilize the soft contact lens in the eye. This method of cutting the lower part of the lens horizontally so that part of it rests on the lower lid. Technology Prism Ballast second stabilization method was used to stabilize the serial contact lenses. By this method there is condensation at the bottom of the lens used in weight in order to stabilize the lens. The Prism Ballast designs have improved since then, and have created a lens with an optical area without a prism and a lens edge profiles thinner with higher oxygen supply. Thin Zone stabilization system there are areas of very thin at the top and bottom of the lens that helps to stabilize. The central part of the lens can be produced in the coming thick contact lens similar libraries and bones, which leads to improving the comfort and performance of your oxygen supply, but sometimes it hurts rotational stability.
Prism Ballast designs newer trying to minimize the interaction with the lower lid, undermines the stability of the lens. There is evidence that recent improvements in contact lens designs Prism Ballast improve some aspects of performance, such as Prism Ballast modern design exhibit fairly good stabilization speeds but are affected by gravity and condensation under the lens interferes with the lower eyelid. Accelerated Stabilization method is a method of assisted stabilization in stabilization zones 4 and a thin lens profile (that does not interfere with the lower eyelid). This method is an easy and fast stabilization time from the moment that make up the eye lens. In addition, rapid stabilization system is not affected by gravity as Prism Ballast designs.
3. Multi-Contact Lens fugitive (multifocal)
Multi-Contact Lens fugitive: These special contact lenses that are designed primarily to the use of age 45 and over with presbyopia (which does not have the ability to focus near). These lenses give the ability to repair the distance, intermediate zone (eg computer) and near (reading).
There are three main designs that give vision centers simultaneously. The designs are kind of fragile, Joint Center and a-books. Breaking design uses a central area which is targeting objects by breaking away from the light and close-by diffraction. Since equal amounts of light passing through both distance element and through the close of the lens element, designs Difrktibiim have no dependency on the dead. To reach the vision Fonktzinlit on all lenses simultaneous expanding design cost to be centered and have low traffic during blinking.
A-lens design school there is a gradual change of curvature along one of the surfaces (front or rear) based on the geometry of conical sections. Flattening rate (Eccentricity) greater than one bifocal lenses and therefore created a positive force growth toward the peripheral portion of the lens. Some of the designs are so close to the center of the highest positive force is the geometrical center and decreases in intensity towards the perimeter.
Concentric designs or Anolariim built from the area Anolari centers which, in most cases, provides powerful control with the power to close a ring around the region remotely. There are also drawings of the center soon. God’s designs are spherical and concentric tend to rise during a closer look. This has led to an effect of increased relative optical power. There are two designs breathe hard lenses and soft contact lens materials.
Types of contact lenses according toughness
1. The contact lenses
Lenses are also difficult as oil – the raw material has Modlos (stiffness) high and small for soft contact lenses. Small diameter lens cornea and lens are more likely to be emitted in relation to a soft lens. All contact lenses are lenses fixed (annual). These lenses names primarily to correct special situations such as astigmatism high (a condition in which there is a taller cylinder), Anaizomtrofih (a big difference in number between the two eyes), horizons (lack of the lens in the eye, as a result of surgery to remove a cataract which is not implanted intraocular lens, or loss of lens background trauma, or lack dislocated lens or lens of birth). More complex situations in which contact lenses are diseases in which there is a distortion of the cornea, such as keratoconus, Aktzih, scarring of the cornea, and Pelucid marginal Degenaration.
2. Soft contact lenses
Soft contact lenses are larger, water and soft chelate much more here very comfortable lineup. Large soft contact lens corneal diameter.
Concepts related to soft contact lenses:
Percentage of water: the percentage of water inside the lens. Measured as a percentage.
Toughness: Toughness attribute describes the raw material of the lens – measured modulus
Precipitation: waterproof lens capability – usually measured contact angle
Beyond oxygen: the ability to transfer oxygen to the cornea lens – measured by a coefficient called Dk
Soft contact lenses are divided into two main types:
Soft contact lens type Hidorg’l
Hidorg’l type of contact lenses (and non-commercial behalf: polyHEMA) Soft contact lenses are the most common. These lenses cost very low stiffness, and have the ability to absorb water. Type of hydrogel contact lenses is very dependent on water transport oxygen. As we increase the percentage of water in the lens to oxygen exceed offenses.
Contact lens type Hidorg’l protein deposits more attractive (compared to contact lenses silicone hydrogel type).
Soft contact lens-type silicon Hidog’l
Silicone hydrogel lenses were launched in 1998 and since then their use has increased. Contact lenses Silicone hydrogel-type high oxygen transferring outstanding. Initial development of the silicone hydrogel designed for use in the assembly and hold (sleep with contact lenses), but shortly afterwards professionals continued to use these drawings of daily compounding.
Cleaning of contact lenses
Hydrogen peroxide solution in combination: a solution containing hydrogen peroxide (usually up to 3%). The lens disinfection is carried out after the contact lens induced according to the manufacturer’s instructions, the time required for cleaning. Today there are many companies that offer cleaning solution of hydrogen peroxide in one step (washer iron tablets).
The versatile solution: a solution that put the lens after each use. There is no need to add a liquid antiseptic solution is also designed for soaking and disinfection. In some of the solutions versatility joint material is also available proteins. When no skimmer multifunction solution, you may want to purchase an enzyme pills and use a period of time recommended by the optometrist, ophthalmologist or producer. In recent years, manufacturers add Lobrikntim (lubricants and wetting) into solutions to help assemble a more pleasant of the lens (Figure 1).
Soap: Designed for daily cleaning of the lens by teaching professionals (after a diagnosis of lipid accumulation). There are soap surfactant materials that help with mechanical abrasion to remove residues.
Enzyme pills: designed for cleaning lenses when there is no permanent solution knuckle protein material. They are used usually fixed lenses, and daily disposable lenses, and since these do not tend to accumulate in sediment that need Bnikoim. Use it under the provisions of professionals.
Assembly and cleaning contact lenses by type
Hard lenses: Mounting a period of one to two years, to the point where the lens is more suitable for assembly, whether because of lens wear and tear, or due to a rise in the register. The disinfection is a daily soap. At the end of each period of assembly must be sent to the laboratory for cleaning lenses.
Daily lenses: Mounting a single day only – no need fumigation (except for sleeping during the day in which to store the lenses in solution).
Bi-weekly lenses: contact lenses for a period of two weeks – daily disinfection with MPS (multi-purpose solutions) except certain types of contact lenses silicone hydrogel type which is not recommended in the MPS. If there are accumulations of secretions protein protein remover should be added every few days.
Monthly lenses: contact lenses for a period of one month. Daily disinfection with MPS (except for certain types of contact lenses silicone hydrogel type which is not recommended in MPS or hydrogen peroxide in combination soap.
Three-monthly lenses: Mounting a period of up to three months. Daily disinfection combined with hydrogen peroxide soap.
Annual contact lenses: Mounting a period of 12 to 15 months. Daily disinfection combined with hydrogen peroxide soap and removes proteins.
Important note: In any case do not wear contact lenses any sleep. Even if the lens bi weekly or monthly, it is absolutely forbidden to sleep with the lenses. Sleep with any contact lens is very dangerous and can cause serious infections of the cornea and the danger of impaired vision.
Contact lens complications
Contact lenses are the most effective cosmetic alternative to glasses however keep in mind that they are still in constant interaction with the surface of the eye, so they can cause complications. Careless use of contact lenses, especially sleep with contact lenses can cause very severe damage to the eyes. Great accessibility of contact lenses and perception as a shelf may dim for contact lens wearers alertness and awareness of eye health changes that may occur following the use of non-contact lens careful.
Complications of contact lenses for contact lens wearers can be connected to a wide variety of reasons, against the backdrop of one or more of the following:
Inflammatory – allergic (hypersensitivity and toxic)
Metabolic (lack of oxygen passage)
All contact lenses complication involving the cornea may cause irreparable damage to eyesight. Against the background of complications are considered the most serious infections among contact lens wearers and often involve the cornea. If feel eye pain accompanied by sudden red, glare and sensitivity to light (photophobia), eye discharge and itchy and blurred vision – a must remove the lenses immediately and contact an ophthalmologist to examine urgently, preferably in an emergency room medical center big eyes. These situations may indicate the involvement of the cornea and is very important for providing adequate treatment as early as possible.
Against the background of infectious complications
Contact lenses among young people is the leading cause of infectious corneal inflammation. This is the most serious complication, which can lead to vision loss or a significant decrease in vision due to corneal scarring. Most cases of infectious keratitis associated bacteria, some of which the most violent and can cause destruction of the cornea within a few days. More than half of the cases involved a bacterium Hfsaodomons Airoginozh. This bacterium has developed resistance to high antibiotics, and found many sources. Hfsaodomons bacteria found in water, plants, soil, nostrils and the flora of the skin, and in fact is the most common bacteria and most accessible person. This is the same bacteria that causes ear infections, pneumonia and urinary tract infections. Other bacteria cause infections of the cornea in light lenses are Stafilokokim (Staph. Epidermidis and Staph. Aureus), and streptococci (Strep. Pneumonia). So contamination may be more rare causes such as Akntambh (Figure 2) and mushrooms.
This complication usually develops in one eye, and is the result of the evolution of microbes under the lens, especially if the lens remains in the eye during sleep, or when the lens disinfection method was not adequate. It is a common complication soft contact lens wearers kind Hidorg’l. When a small ulcer is reflected foreign body sensation, itching, discomfort and lacrimation. When Advanced ulcer is manifested in intense pain, redness substantial, multi provision and decreased vision. These signs often appear after morning awakening from sleep with contact lenses. The appearance of these symptoms require an urgent appeal to the emergency room eyes.
Against the background of inflammatory complications – are allergic
Red Eye as a result of contact lenses
This complication is called Contact Lens Acute Red Eye = CLARE, and is an inflammatory response of the eye surface usually in one eye (10% of cases are in both eyes). This inflammation is characterized by redness with infiltrates that may appear in the volume of the cornea. The incidence is between 5% to 30% of contact lens wearers and is very common in a long lineup of lenses type Hidorg’l. Complaints of mild to moderate pain, photophobia (sensitivity and pain upon exposure to light) and lacrimation.
This complication is called IK (Infiltrative Keratitis), which are small inflammatory infiltrates, especially the volume of the cornea, the region bordering on, or about 1 mm into the cornea from the area bordering. These infiltrates are clusters of white blood cells, reaching the cornea with tears or from the bordering Depp, in response to bacteria and sediment on the surface of the lens. There are many symptoms include red eye, lacrimation, mild to moderate irritation in the eye, and slight pain.
Papillae upper eyelids – Giant papillary conjunctivitis
This complication is caused by constant friction between the conjunctiva tarsal covers the upper eyelid and the lens (Figure 3) .. This friction Gormm trauma constant of the conjunctiva, and the appearance of inflammatory response in allergic conjunctivitis against the lens, and also against the cleaning solution of the lens (some lenses ). The lens material combined with protein deposits on contact lenses forming the allergic response. Complication characterized by multiple papillae in size up to 1 mm on the inside of the eyelid. When turning the lid see small clumps looking rough. Weddings are both multiple mucous discharge, itching, foreign body sensation and discomfort wearing contact lenses, lens removal increases precisely.
Exposure to toxic foreign substances
Multi-purpose solutions or Multi Purpose Solutions (MPS) (one bottle systems) have been created to allow a combination of cleaning, washing and disinfection. Cement was compounded in recent years, new materials to remove proteins from the lens. In addition, these solutions have preservatives are bacteria-killing substances, such as Polyaminopropyl Biguanide, Polyhexanide hydrochloride, Folikoatrniom-1, and other materials. These substances can cause toxic reaction and hypersensitivity among contact lens wearers. Preservatives such as thimerosal first generation and chlorhexidine, when used in high concentrations, causing strong reactions of hypersensitivity soon as the lenses. The complaints are discomfort and foreign body sensation, and sometimes a burning sensation and redness easy. In most cases no complaints whatsoever.
Against the background of traumatic complications
Drooping eyelid (ptosis)
This type of complication is defined as being traumatic or common mechanical components and hard contact lenses. While blinking (10-15 times per minute) slightly injured eyelid hard contact lens damage accumulates with time to drooping of the eyelid in one or both. Railway contact lenses is the most common cause drooping eyelids young people.
Injuries to the cornea
Hard contact lens or a soft contact lens may damage the cornea rigid. The dynamic movement of the lens in combination with the lens stiffness leads to repeated injury of corneal epithelial (erosions) and scratch the cornea epithelium (Figure 4). Symptoms are often mild pain and blurred vision and injury cases is front and center of the pupil. Sometimes the injury is created at installation or the removal lens.
These pills contain Lucyna (originating in tears) generated from the lens (lens dribble them) and can reach the size of the corneal epithelium directs our damage. In acute cases interfere with vision Hmotzin balls.
Changing the structure of the cornea
This complication called corneal warpage and causing a change in topography of cornea and irregular astigmatism (irregular structure of the surface of the cornea, with targeted areas of high curvature than usual). This condition can be diagnosed using a computerized mapping of the cornea. Complication caused by mechanical stress of the lens combined with corneal edema. The symptoms are blurred vision and halos.
Corneal epithelium defect located at the top
Lens grown relatively rigid cost can have greater mechanical effect on the corneal surface, causing an eclipse corneal epithelium located in the top or in a foreign language: (SEAL) Superior epithelial arcuate lesion.
Conjunctival epithelial suspension
This complication is called Conjunctival epithelial flaps (CEFs) and appears in the contact lenses with edge profile (scope lens) with a single design or is gradual. Profile sharp edge of lens will make cuts in the conjunctiva in the composition of the contact lenses daily disposable.
Against the background of metabolic damage
Metabolic damage belong to a broader range of damages as a result of lack of oxygen to the contact lenses. Offences oxygen soft contact lens type Hidorg’l and some hard lenses are high. In these cases, corneal changes may occur against the background of hypoxia (oxygen connected tissue). Complications include:
New blood vessel growth in the cornea
Blood vessel growth in the cornea (corneal Neovascularization) are caused due to the release of growth factors of blood vessels (VEGF) as a result of passage of oxygen.
Corpuscles accumulated layer of dead cells in the epithelium, especially epithelium Hbzli response to hypoxia.
Edema is caused in response to hypoxia, and occurs because transition anaerobic respiration cells, involves the accumulation of lactic acid products in the stroma of the cornea, Struma water penetration to balance the osmotic pressure, and corneal edema formation. Complaints of decreased vision, halos and blind.
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