Eye Conditions

          

   

  

In a normal eye, the cornea and the lens each have a convex, perfectly spherical surface rather like a slice taken from a football (the lens is actually bi-convex, having both sides spherical). This optical system ensures that all of the light that enters the eye is focused sharply on to the retina.


In an astigmatic eye, the shape of the cornea (or sometimes the lens) is more oval, much like the shape of a rugby ball. In this case the cornea has two different curvatures whose ‘meridians’ or ‘axes’ are at right angles to each other. Only the light that is focused by one of these curvatures forms a sharp image on the retina. The remainder focuses either behind or in front of the retina, according to the degree of long- or short-sightedness. The result is blurred vision.


All these conditions can be corrected with spectacles or contact lenses..

Also known as short-sightedness or nearsightedness. The ability to only see objects at short distances clearly.  Myopia is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed.

Also known as long-sightedness or farsightedness. In younger patients (under the age of 40) the ability to only see objects at far distances clearly. Hypermetropia is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or the lens cannot become round enough), causing difficulty focussing on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any distance. As an object moves toward the eye, the eye must increase its optical power to keep the image in focus on the retina. If the power of the cornea and lens is insufficient, as in hypermetropia, the image will appear blurred.

Presbyopia is a condition where the eye exhibits a progressively diminished ability to focus on near objects with age. Normally over the age of 40.