What does the eye consist of and how does it work?
Vision, the most important of human senses, is the source of our brain supply with a multitude of information, impressions, images and shapes. The eye, despite its very small size, consists of various parts, each of which has its own competence. The overall operation of the eye is reminiscent of that of the camera.
In particular, the rays of light enter thecornea and concentrate on the crystalline lens passing through the opening of the daughter, we aim to focus and capture as a picture on the retina. Then, this image passes to the brain and is decoded. Consequently,To properly and clearly transfer an image of the outside world to the brain, a perfect "cooperation" between the cornea, the lens and theretina. However, the length of the eye may vary and affect the focus of the image and its formation before or after the retina, thereby causing so -called refractive abnormalities.
What are refractive abnormalities?
Refractive abnormalities or otherwise irregularities of the eye are myopia, astigmatism, hypermetropia and presbyopia.
What is myopia and how is it treated?
Myopia is the refractive anomaly in which the image of the eye from the outside world does not focus, as it should, on the retina, but in front of it.Symptoms a myopic has are blurred when looking away while vision remains clean when looking close.
Myopia is considered the most common refractive abnormality and, under normal conditions, occurs during school age either because the length of the eye is longer than normal, or because the curvature of the eye is greater than normal, or because of both of these factors. It is also known that myopia may be hereditary, especially in high degree cases.
Myopia is treated and corrected either with glasses of vision where negative eye lenses ("divergent lenses"), either with contact lenses or refractive surgery withExcimer Laser.
What is hypermetropia and how is it treated?
Hypermetropia is the refractive anomaly in which the image of the eye receives does not focus, as it should, on the retina but behind it. The symptoms of a hypermetropa are blurred when it looks close, while a gradual decrease in distant vision is observed.
Under normal conditions,Hypermetropia occurs either because the length or curvature of the eye is smaller, or because of both of these factors. Most hypermmetry under the age of 35 are able to see clearly without the need for a correction of the problem. However, due to the decrease in the adaptive ability of the eyes due to time (and zeroed at the age of about 60), the ability to vision nearby is significantly limited, while various symptoms such as reading tiredness, headaches, weakness concentration et al.
Hypermetropia It is treated and corrected either with glasses of vision where positive ophthalmic lens ("converging lenses") are placed, either with contact lenses or refractive surgery with Excimer Laser.
What is astigmatism and how is it treated?
Astigmatism is the refractive anomaly in which the eye -taking image does not focus on a specific spot on the retina but on two lines perpendicular to each other ("sturm conical").
The symptoms of one with astigmatism depends on the degree they have. If, for example, the degree is very small, no vision problems arise because the adaptive ability of the eyes neutralizes the problem of refractive abnormality. Nevertheless,As the degree grows older, vision becomes blurred, images are not clearly distinguished while still causing tiredness in the eyes, especially when reading or using a computer.
Usually, astigmatism occurs due to disturbances in the curved curved and rarely due to lens convex disorders.In most cases astigmatism does not change throughout a man's life and occurs at birth. Consequently, over the years, the increase in the degree of astigmatism is not due to refractive anomaly but to a decrease in the adaptive ability of our eyes.
There are two kinds of astigmatism: Thesmooth who is easily corrected, as well as theabnormal astigmatism (which may be due to keratoconus, wounds or keratitis), whose correction is more difficult to achieve. Finally, there is a possibility that astigmatism will coexist with myopia or hypermetropia or even being "mixed" (say, hypermetropia with myopic astigmatism).
AstigmatismIt is treated and corrected either with glasses of vision where cylindrical eye lenses or spherical cylinder (when there is myopia or hypermetropia), or with contact lenses (soft or semi -hard, as appropriate), or with a refractive laser surgery..
What is presbyopia and how is it treated?
Presbyopia is a normal refractive abnormality and evolution of the visual system whichIt appears to all people over 40 years of age and is due to changes in the crystalloid lens of the eye.
The crystalline lens is extremely elastic to contribute to the proper focus of images at all distances. As the years go by, however, this lens gradually becomes inelastic resulting in the ability to adapt the vision, and in particular at close distances.
Symptoms of presbyopia are eye fatigue and headaches after working nearby, while this refractive abnormality can coexist with myopia, hypermetropia or astigmatism.
End,The correction of presbyopia is carried out either by vision glasses (single -folded, duplicates or multifocal), eitherwithcontact lenses (multifocal or simple in conjunction with the Monovision method, in which one eye is used to see the other one away), eitherby surgery (with Excimer Laser or using multifocal intraocular).