Eye problem demands quick work

Macular degeneration, often called age-related macular degeneration (AMD), is a chronic eye disease and one of the leading causes of vision loss among the over-50s, though women are at greater risk than men. AMD must be diagnosed early as current treatments can only stabilise it or improve some symptoms. The disease cannot be cured.

The macula is the central and most important area of the retina, the light-sensitive tissue lining the inner surface of the eye. The macula is composed of special retinal cells (the cone cells) responsible for the detailed and coloured vision that is needed in particular for reading, driving and recognising people’s faces. 

There are two types of AMD. The most common is the dry form and occurs in about 90 per cent of cases. The wet form is an advanced and more severe stage of AMD.

The cause of dry AMD is unknown. In some predisposed people, the cone cells in one area of the macula gradually lose their function and die. The affected area will induce painless blurred eyesight in the central part of the field of vision. 

The disease may not initially be noticed if only one eye is affected because the other eye may be able to fully compensate for the impaired vision. In such a case, the disease may progress towards a more serious disorder before it is recognised and this alone justifies the need to have regular eye check even if your vision appears normal. The early signs of dry AMD are the presence of yellow spots (extra-cellular particles deposit) called drusen, which will be detected during dilated eye exam.

Wet AMD is due to the abnormal growth of new vessels behind the retina. These “neo-vessels” result from a lack of oxygen and nutrients to the retina and are supposed to provide better oxygenation to the eye. Unfortunately, these vessels are fragile and often leak fluid or blood, which directly damage the macula. 

The straight lines, which appear broken or wavy, are one of the initial symptoms of wet AMD. Loss of central vision may happen rapidly if treatment of wet AMD is not promptly instituted. 

The risk of AMD increases with age although some middle age individuals may also suffer from macular degeneration. Other risk factors include family history of AMD, smoking, hypertension, obesity and high cholesterol.

AMD is diagnosed by several tests including visual acuity tests, ocular pressure test and, more specifically, with the fluorescein angiogram test to visualise the vascularisation around the retina. In addition, a non-invasive imaging test called Optical Coherence Tomography (OCT) is used to assess the various damaged areas of the retina due to the disease development.

Treatment has to be initiated as early as possible to slow down the evolution of AMD. Depending on the form and stage, treatments may include laser surgery and photodynamic therapy (a special drug injected intravenously attaches to the inner wall of the new vessels and a special light is used to activate the drug to destroy the vessels). For wet AMD, new drugs (anti-VEGF medicines) may be injected into the eye to stop the formation of new abnormal vessels. 

Most of the AMD treatments are effective in slowing down the loss of vision and in some cases even improve eyesight. However, laser surgery and injections of anti-VEGF products may have to be repeated depending on the outcome. Regular monitoring of the eyesight is essential. 

As the loss of vision cannot be reversed at the moment, prevention remains the main weapon against AMD. Healthy lifestyle and/or specific treatment should control any existing risk factors such as smoking, obesity, hypertension and high blood lipids. The most important measure remains undergoing systematic annual eye check-up from the age of 50 up. 

 

 

Dr Gerard Lalande is managing director of CEO-Health, which provides medical referrals for expatriates and customised executive medical check-ups in Thailand. He can be contacted at gerard.lalande@ ceo-health.com.