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Vision Problems: Myopia, Hyperopia, Astigmatism & Presbyopia

This page looks at some of the most common vision problems, their signs and symptoms and the options for treatment. On this page you will find information for the following visual deficiencies:




Myopia or Short sightedness



What are the causes of Myopia?


Short sightedness, or myopia, has become common over recent years. Although there is no definite answer as to why more people are now developing myopia, environmental factors, like eye fatigue, caused by the extensive use of laptops, paired with a genetic predisposition for myopia, are thought to be examples of possible causes for the noticeable surge in numbers.

Myopia tends to develop during childhood and the teenage years and is more common with women than men. The condition manifests as a result of an overly elongated eyeball, which interferes with the cornea's focusing abilities, causing light rays to focus in front of the retina rather than its surface. Myopia can also occur due to the curved shape of the cornea and/or the lens, rendering the extended eyeball a poor fit. Short sightedness can also manifest as a result of both of these issues.

If your parents suffer from short sightedness, the chances of you experiencing it are increased. This condition can stabilise as children grow into adults, but can also worsen with age.



Symptoms and signs of Myopia


With myopia, you'll find it difficult to focus on things placed at a distance from you. For instance road signs or words on a blackboard may be really hard for you to read. Looking at objects that are close to you should be no problem though, like reading books, or viewing a computer screen.

Squinting is another symptom of myopia, as is eye strain, headaches and a feeling of fatigue when engaging in activities like sports or driving. If you experience these symptoms while wearing your contact lenses or glasses, get a comprehensive eye examination with your optician. You may need a stronger prescription.



Treatment for Myopia


Contact Lens

Corrective glasses, contact lenses or refractive surgery are treatments used to correct myopia. If myopia is severe, you might have to wear your corrective glasses or contact lenses constantly, but if it's moderate, you'll only need to wear them for distance viewing.

Refractive surgery is another option to consider and you may find you no longer need glasses or contact lenses after its completion. An excimer laser is often used to perform refractive surgery, which consists of two forms, being photorefractive keratectomy (PRK) or LASIK. With PRK a layer of corneal tissue is removed to flatten the cornea, allowing light rays to accurately focus on the retina. With the LASIK procedure a tiny flap is created from the plane of the cornea. The laser then removes part of the corneal tissue and the flap is returned back to its original position. LASIK surgery is the more common of the two, although it's not suitable for children or teenagers.

Onthokeratology is a non-surgical option, requiring you to wear specially designed hard gas permeable lenses at night, to reshape the cornea. When the lenses are removed in the morning, the cornea retains its new shape temporarily, allowing you to see more clearly during the day without glasses or contact lenses. Phakic Intraocular Lenses (Phakik IOLs) are somewhat like contact lenses, although they are permanent and placed inside of the eye. Also no maintenance is needed with this procedure.




Hyperopia or Long sightedness



What are the causes for Hyperopia?


Hyperopia is the medical term used for long sightedness. People experiencing hyperopia can see objects from a distance, but have difficulty focusing on objects that are in close proximity to them. This condition manifests as a result of light rays entering the eye's focus behind the retina, as opposed to hitting the retina directly. If you have hyperopia your eyeball will be shorter than normal. Children born with hyperopia often grow out of it, as their eyeballs extend to a normal size.



Symptoms of Hyperopia


Headaches or eye strain are common symptoms of hyperopia and you might find yourself squinting or your eyes may feel fatigued when performing short sighted tasks. Book an appointment with your optician for an eye exam if you are experiencing any of these symptoms, to ensure you have the correct prescription.



Treatment for Hyperopia


Glasses and contact lenses can help correct hyperopia by changing the way light rays bend into the eyes. With long sightedness you may have to wear your glasses constantly, or only when reading, working on your computer, or carrying out any other short sighted tasks.

Refractive surgery, like LASIK or Conductive Keratoplasty (CK), which is a non-laser refractive surgery, can also help to correct hyperopia, either eliminating or reducing the use of contact lenses and glasses.




Astigmatism



Astigmatism Diagram

What are the causes of Astigmatism?


Astigmatism is a condition that is often misunderstood by many. Like short sightedness and long sightedness, this condition is the result of a refractive error, which means it is not an eye health issue, but a problem with the way the eye focuses light. With this condition, light is not directed to a single focal point on the retina for clear vision. Instead multiple focal points occur in the front of the retina, behind it, or on both of these sites.

An irregularly shaped cornea or lens can be a causal factor for astigmatism. A normally shaped cornea is round like a football, but with astigmatism the cornea might resemble the shape of a rugby ball. This irregular shape disrupts light distribution, making images appear blurred. Some people are born with astigmatism, although injuries to the cornea or specific diseases can make this condition manifest.

Astigmatism can also be caused by the shape of the lens inside eye, a condition that is referred to as lenticular astigmatism. This form is different from corneal astigmatism, which is the more common type.


Symptoms of Astigmatism


If you suffer from astigmatism you'll probably experience blurred vision and objects in the distance might appear somewhat distorted. If astigmatism remains uncorrected you'll most likely suffer from eye strain and headaches. These symptoms will be exacerbated when partaking in specific tasks like reading or viewing the computer screen for a prolonged period of time.



Various types of Astigmatism


Three types of astigmatism exist, being myopic, hyperopic and mixed astigmatism. Myopic astigmatism occurs when both or one principal meridian of the eye is short sighted. Hyperopic astigmatism manifests when both of the principal meridians are long sighted and mixed astigmatism is descriptive of one meridian being short sighted and the other long sighted. As well as these classifications, astigmatism is identified as being irregular and regular.

Irregular astigmatism occurs when the principal meridians are not perpendicular to each other, while with regular astigmatism, the principal meridians are perpendicular to each other but 90 degrees apart. Regular corneal astigmatism is identified by the rugby shaped eyeball and is the most common of two.



Treatment for Astigmatism


Astigmatism often occurs with myopia and hyperopia and as with these conditions glasses, contact lenses and refractive surgery are generally used as a form of correction. A cylinder type lens can be used in addition to spherical lenses that are applied to correct short and long sightedness. This serves to correct the disproportionate powers of the eyes two principal meridians.

Glasses used to treat astigmatism contain lenses that are specifically crafted to compensate for the cornea's uneven shape. As light passes through the corrective lens, it is directed onto the retina to improve vision. Gas permeable contact lenses are effective in treating astigmatism and their hard structure makes them an ideal replacement for the cornea's surface. Soft lens prescriptions for astigmatism also consist of a sphere and cylinder power and axis designation.




Presbyopia



What are the causes of Presbyopia?


Presbyopia is a form of long sightedness that generally manifests with age. This condition can affect anyone, even if you've always had perfect eyesight and vision. Presbyopia typically begins to appear around the age of 40 and you may notice your eyesight becoming blurry when carrying out tasks like reading or sewing. If you are short sighted and wear glasses or contact lenses, presbyopia can still affect you, causing fuzzy vision with objects that are close up.

Myopia, hyperopia and astigmatism are all conditions manifesting due to an irregularity in the shape of the eyeball, as well as genetic and environmental factors. Presbyopia however differs, in the sense that it is developed as a result of aging. As you get older, the natural lens inside of your eye thickens, loosing flexibility. The lens hardens, becoming rigid with reduced elasticity and the muscle fibres that surround the lens becomes less supple. All of these factors make it a challenge for the eye to focus on objects that are placed in close proximity.



Symptoms of Presbyopia


If you have presbyopia, you will have developed a tendency to hold objects, like books and newspapers, at arm's length away in order to read the fine print clearly. Text on pages of books, newspapers and magazines will appear blurry if you try to read them at a normal distance. You might even experience eye-strain and headaches if you attempt to carry out tasks like needle work, jewellery making or handwriting, feeling quite fatigued.



Treatment for Presbyopia


Bifocal or varifocal lenses are more often used to treat presbyopia. Bifocal glasses have two points of focus, with the upper part of the lens being used to view things from a distance, while the lower functions for objects that are in close proximity. These lenses are characterised by a visible line separating both prescriptions.

Varifocals are similar to bifocals, in the sense that they can be used to view things from a distance and closer up, but there is no visible separating line. These lenses offer a more gradual transition between the two lens prescriptions and are favoured by those concerned with issues of aesthetics and personal image.

Reading glasses may also be prescribed for presbyopia. These glasses are worn whenever short sighted tasks are being carried out. You can also wear reading glasses with contact lenses, although your optician will have to prescribe those for you.

Multifocal contact lenses are another choice of treatment for presbyopia, coming in soft and gas permeable options. Monovision contact lenses, where one lens is used for distance viewing and the other for short sighted vision, are also used to treat presbyopia. With monovision lenses, the brain automatically switches to the appropriate eye for each task, although while wearing them you may experience a loss of depth of perception, as well as reduced visual sharpness.

A stronger prescription will inevitably be required over time, so it is important to get regular check-ups with your optician, to ensure your prescription is still functioning at its optimal level for your eyesight.

A PRELEX operation is the surgical option for presbyopia. This procedure removes the old and inflexible lens, replacing it with an artificial one and is performed under local anaesthetic.



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