Our sense of sight is complex. It needs the eyes and brain to work together to give us the ability to see the world around us.
Our vision works by the cornea and lens refracting light to focus on the retina at the very back of the eye. It is the retina’s job to convert the light into electrical impulses for sending to the brain which then produces an image. When there are imperfections in the eye, it can prevent the light from focusing on the retina. The faults usually relate to the shape of the eye.
Myopia
Myopia or nearsightedness occurs when the light is focused in front of the retina rather than directly on it. The cornea may be too curved or the eyeball too long.
Nearsighted people can often read or work on the computer without a problem but have trouble seeing the board at school or driving.
Symptoms of myopia include squinting, eye strain, headaches and feeling tired when driving or playing a sport. Myopia usually begins in childhood and stabilises in early adulthood, but for some people, it can progress with age. The incidence of myopia has increased worldwide in recent years. It is thought the more prevalent use of computers by children and a genetic predisposition may be the causes.
Myopia can be corrected with glasses or contact lenses which are either worn all the time or only when clear distance vision is required like when driving or watching a movie. Glasses and contact lens prescription for myopia begin with a minus sign. The higher the number that follows, the more nearsighted the wearer is.
Laser surgery is an option for some people with myopia. For others wanting to avoid surgery, Corneal Refractive Therapy or Orthokeratology is an option. Wearing rigid contact lenses while sleeping changes the shape of the cornea temporarily allowing the patient to see without contact lenses or glasses during the day.
Hyperopia
A farsighted person has hyperopia which occurs when light is focused behind the retina. People who are farsighted can see people in the distance but have difficulty reading a book in front of them. The eyeball is shorter than normal. Some children diagnosed with hyperopia will outgrow it as the eye may lengthen as they grow. Hyperopia is less common than myopia.
Hyperopia can be treated with glasses or contact lenses which change the way the light rays bend into the eyes. Prescriptions for glasses and contact lenses for people with hyperopia begin with plus numbers. Glasses may be worn all the time or only during close up work. Laser surgery is another option for treating hyperopia.
If you have any symptoms or difficulties seeing clearly, see an optometrist for a test to see if you have myopia or hyperopia.
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