Eyecare - Your eyes
Kings Langley - 12 High Street, Kings Langley, WD4 8BH

Your eyes
Normal Vision (Emmetropia)

In the human eye there are two powerful focusing elements, the cornea (clear window to the eye) and the crystalline lens. They have the ability to focus light on to the retina (at the back of the eye) from all distances. When an object has to be viewed close, such as reading a book, the lens changes shape and the power of the eye increases bringing the print into focus. The lens relaxes and decreases power to see objects further away. In some ways the eye is similar to a camera. The cornea is the lens and the retina is the film or image capture.

Short sight (Myopia), Nearsightedness

Occurs in over 25% of the population. The length of the eyeball is too short and so objects are blurred as light rays fall short of the retina. Corrective lenses will place the image back on the retina, giving clear sight.

Long sight (Hyperopia), Farsightedness

Objects appear more blurred the closer they are to the eye, as the length of the eyeball is too long and hence light rays fall 'behind' the retina. Corrective lenses will place the image back on the retina.

Astigmatism

Is caused by a distortion in the shape of the cornea. Normally the cornea is spherical like a soccer ball, but an astigmatic cornea is like a rugby ball. Vision will appear blurred at all distances, usually with accompanying short or long sightedness. Similar corrective vision can be acheived as in other defects of sight.

Presbyopia

Affects all individuals from the age of around 45 years. In presbyopia the lens loses some of its elasticity and cannot change shape enough to focus on near objects. If the person already has sight correction when presbyopia occurs then varifocal glasses, contact lenses or separate pairs of glasses will be required.