In a myopic, or short-sighted eye, the eyeball is not spherical but instead is too long, tending towards the shape of an egg. This means light rays entering the eye are unable to focus on the light-sensitive part of the eye called the retina. In high myopia, the excessive elongation of the eyeball leads to degeneration of the retina and in particular to the macula, which has the highest concentration of light sensitive cells that interpret colour images.
Macular holes are small and develop at the centre of the macula. Symptoms of macular holes are similar to that of age-related macular degeneration. In the early stage of a macular hole, people may notice a slight distortion or blurriness in their straight-ahead vision. Straight lines or objects can begin to look bent or wavy. Reading and performing other routine tasks with the affected eye become difficult. Although some macular holes can seal themselves and do not require any treatment, surgery is necessary in many cases to help improve vision.
Diabetic macular oedema (DMO)
DMO is the most common cause of vision loss in diabetics. Oedema is a build up of fluid under the macula caused by leaky blood vessels. DMO is a complication of diabetic retinopathy and results in a condition very similar to wet AMD. Download Diabetic Macular Oedema for further information about this condition.
Retinal vein occlusion (RVO)
RVO is one of the most common causes of sudden, painless, unilateral (affecting one eye) loss of vision. Although it can occur at almost any age, it typically affects older people. The condition means one of the veins draining blood out of the eye has become blocked, causing blood and other fluids to leak into the retina, which then causes bruising and swelling as well as lack of oxygen. This interferes with the light receptor cells and reduces vision.
For further information visit www.moorfields.nhs.uk