Long Sight (Hypermetropia)
Hypermetropia occurs when light is focused behind the retina. In reality, light cannot actually be focused behind the retina. So, the lens changes its thickness (becomes fatter or more rounded) which aims to bring the light into focus on the retina – a process called accommodation.
But, people with long sight cannot accommodate fully and so the light does not focus sharply and vision is blurred. This occurs because either the eyeball is too short, the cornea is too flat, or the lens cannot become round enough.
People with a minor degree of long sight, can usually see at distance, and their near sight is clear. However, a person with long sight may get tiring of the eyes, often with a headache and vision discomfort. People with more severe hypermetropia are not able to see near objects clearly in focus. Long sight means exactly what the term suggests. You are sighted (you can see) distant (long) objects.
What causes long-sightedness?
The causes of hypermetropia are usually genetic (hereditary). Long-sightedness can occur at any age but it tends to become more noticeable above the age of 40 years.
What are the symptoms?
The main symptom is a difficulty with near vision. ‘Tiring’ of the eyes (asthenopia) is common and long-sighted people may have headaches and uncomfortable vision.
What is the treatment for long-sightedness?
The simplest, cheapest and safest way to correct long-sightedness is with glasses. Convex prescription lenses (called plus lenses) are used to bend light rays slightly inwards. The light rays then have a lesser angle to bend back to focus when travelling through the cornea and lens. As a result, the light rays focus further forward – on the retina..
These do the same job as glasses. Many different types of contact lenses are available.