Hyperopia (long-sightedness)

In a long-sighted or hyperopic patient the eye is normally too short for the focussing power of the eye. Light rays enter the eye from a distant object and are focussed on a point behind the retina, resulting in an out-of-focus or blurred image. 

The focussing ability of an eye is determined by the curvature of the cornea (front surface), the power of the crystalline lens, and the eye’s overall length.

The eye has the ability to increase its focussing power. The shape of the cornea and the length of the eye are fixed, but the crystalline lens is flexible, and we can bring objects into focus by accommodating. Using muscles surrounding the crystalline lens, the lens is squeezed into a more curved shape which focusses the light onto the retina. This process (known as accommodation) is normally used to allow the eye to focus on near objects. Using this mechanism, small amounts of hyperopia can be tolerated without any discomfort. Consequently, parents may not be aware that their child is long-sighted. This is the reason why children should be checked by an ophthalmologist / optometrist prior to school, to ensure that any small errors are not going to interfere with their ability to learn to read, for example.

Larger amounts of hyperopia may result in discomfort, or even in one of the eyes turning inwards. This can be corrected with either glasses or contact lenses.

Small amounts of hyperopia that have not caused any symptoms in earlier years may become problematic as we get older. The crystalline lens in the eye becomes progressively less flexible as we age, and it becomes more difficult for us to squeeze the lens into the shape required to focus clearly. The error may not be discovered until later in life, but probably was there from early years, masked by the flexibility of the crystalline lens. Again, these errors can be corrected with glasses or contact lenses.

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