HEALTH One reason for blurred vision

Macular Degeneration causes the middle of the visual field to appear blurred, as shown in this simulation.

Missing the middle bit?


Áine Higgins

Macular degeneration causes loss of central vision and is the leading cause of registered vision impairment for people over 50 in the western world.
The eye is like a camera. The front part is clear and contains the lens that focuses light onto the retina at the back, which is like the film in the camera. In the centre of the retina lies the macula, an area the size of a grain of rice, which contains the cells that process the fine detail and colour of what you see. The rest of the retina lying outside the macula processes your peripheral vision.

What is macular degeneration?
Macular degeneration (MD) causes the macula to deteriorate. If it occurs later in life, it is called age-related macular degeneration (AMD). It leads to varying degrees of visual impairment and will impede daily activities such as reading, driving, recognising faces and working with fine detail. It does not lead to total blindness, since peripheral vision is not lost.
As the macula has many roles in providing us with fine and detailed vision a significant amount of waste products are generated in this area. Ordinarily these waste products are carried away efficiently by cells at the back of the eye therfore ensuring this vital region is kept clear and healthy. When macular degeneration begins this waste disposal system breaks down. This leads to waste accumulation, cell destruction and disruption of central vision.

Two types
There are two types of MD – dry or wet. Dry MD is the steady deterioration of the cells of the macula. Onset and progression is normally gradual. Unfortunately, there is currently no treatment for Dry MD, but those with the condition can be considerably helped by the use of low vision aids. Giving up smoking, maintaining a healthy diet and/or the use of nutritional supplements may stabilise or slow down development of both types of MD.
Wet MD results from the growth of abnormal blood vessels lying behind the macula. These vessels leak fluid causing damage and scarring to the macula itself, leading to loss of central vision. Wet MD often starts suddenly and can progress very quickly.

Symptoms
Macular degeneration is not painful. In the early stages your central vision may only be slightly blurred or distorted, with individuals reporting difficulty performing details tasks such as sewing or reading small print. Straight lines appearing wavy is also an indication of changes occurring at the macula. Macular degeneration usually involves both eyes, although one may be affected long before the other. This sometimes makes the condition difficult to notice as the sight from the “good” eye is compensating for the loss in the affected eye.

What are the risk factors?
Several factors increase the risk of MD. Smoking roughly doubles the risk, while high-fat diets, sun exposure and age also increase the chances of developing MD. Genetics can also play a part, with first-degree relatives of patients with wet MD being more prone.

Prevention
If you smoke stop now! Also, try to eat a diet rich in green leafy vegetables, wear sunglasses when outdoors, and go for regular eye examinations, so that early changes can be detected and early treatment started.
If you have noticed a sudden change in your vision, ring an optician straight away to book an appointment and explain your symptoms. The optician can then refer you direct to a retinal specialist at the most suitable clinic. For suspected Wet MD, a patient should be seen urgently, within a week if possible. For Dry MD, the change will be more gradual and a patient should receive an opthalmic assessment within three months.

Aine Higgins is an optician based in Mongey’s Opticians, Castlebar and Ballinrobe. She was the first Irish optician to be nominated for the UK and Ireland Optician of the Year 2009.