The images you see to the left illustrate how easy it is to diagnose macular degeneration. Called an Amsler Grid or Amsler Chart, it’s recommended by ophthalmologists that everyone over the age of 60 keep one on hand.
To check your sight: hold the grid at your normal reading distance, cover one eye and look at the dot in the centre. If any of the lines appear wavy, are missing or blurred, please contact your eyecare professional immediately.
The earliest changes occur at the level of the Bruch’s membrane, which is like a waterproof membrane between the retina and the underlying choroid, followed by retinal pigment epithelium (RPE) and the photoreceptors of the eye.
The retina functions like a busy photochemical processing plant that generates chemical residue waste products. In the early stages, the Bruch’s membrane starts to thicken in patches or mounds called drusen. They can vary in different people in size, amount, age of onset and can differ in the type of fat (liquid) that forms around them (this is not related to obesity issues). This is the beginnings of age-related maculopathy (ARM). The larger drusen, especially those that grow larger and merge, can progress to become a more severe macular degeneration.
There are two types of macular degeneration – wet and dry. Currently it’s not possible to know which eye will be affected, or which type may develop.
Depending on the specific form of macular degeneration, symptoms will vary with the most obvious being blurred vision, shadows or missing areas of vision and distorted vision (straight lines appearing wavy, for example).
Discerning colours can also be difficult, particularly detecting darks from other darks, or light from other lights. Slower adaptation to dark conditions after being exposed to bright lights may also be noticeable – for instance, entering a darkened room after being out in bright sunlight.
Macular degeneration won’t lead to absolute overall blindness, but the loss of central vision represents the loss of the most important vision for reading text or numbers, recognising faces, driving and independent living. Therefore, it’s important to seek attention urgently if you believe you may be suffering from macular degeneration.
There are three primary causes of age related macular degeneration: age, family history of macular degeneration and smoking. There are other possible factors such as exposure to ultra violet light and genetic predispositions.
The main measures for management of macular degeneration involve prevention and early detection.
The simple way to check yourself is to look at an Amsler chart (sometimes called an Amsler Grid), which is readily available free from Vision Eye Institute clinics.
It’s important to test each eye separately, making sure you wear your glasses. Cover the other eye when checking.
For wet macular degeneration, the mainstay of treatment – intravitreal injections of drugs that shrink abnormal blood vessels and dry up the abnormal macular fluid (oedema) – represents one of the truly significant advances in medical history.
Wet macular degeneration used to be a fast track to legal blindness until as recently as 5-10 years ago, but with intravitreal injections, it is now possible to prevent further vision loss in 95% of macular degeneration patients and improve vision significantly by up to 40%, thanks to the use of repeated intravitreal injections of drugs. This requires early detection and early intervention as well as the use of repeated intravitreal injections of drugs.
Some patients’ macula don’t dry up with intravitreal injections, and such eyes may require photodynamic therapy (PDT) in addition to injection treatments.
For wet macular degeneration, it has been an exciting new era. Although there are no cures available, treatment does suppress the problem for a period of time. So, at present, any wet macular degeneration patient will require ongoing treatment.
For dry macular degeneration, although there is no specific treatment, the aim for the future is to re-grow the worn out macula and repopulate it with new macular tissue. Ongoing research is attempting to solve this, but in the meantime, low vision aids are helpful in aiding the atrophic ‘dry’ macular degeneration to see as much as possible.