What is macula?
Macula is situated in the centre of the retina and only 500 micrometres in diameter. It is responsible for central vision and fine details of the image. The healthy maculae enable us to carry out many everyday tasks, such as differentiate colours and faces, reading, writing, cutting food and driving etc.
Who will be the high risk macular degeneration sufferers? What are the symptoms?
The elderly and seriously short-sighted people (pathological myopia of over 600 degrees) are particularly prone to this condition. Given that the disease manifests itself in the left and right eyes at different times, the patient may first experience poor central vision or blurred vision in only one eye. Examples are failing to see clearly the route number of an approaching bus or a friend walking towards them. Distorted view, blind spots and fading colours may also appear in time. In serious cases, central vision is completely lost and sight of the other eye deteriorates.
What are the causes?
Macular degeneration is one of the degenerations of the retina. When macular cells begin to degenerate, metabolic waste will be acculumated in the retinal layers which would impair the maculars function of maintaining clear vision. This condition is known as dry macular degeneration. If it deteriorates, abnormal retinal blood vessels will proliferate and there are also chances of developing massive exudation and scar, i.e. wet macular degeneration. At this stage, macular photoreceptor cells are permanently damaged and vision will fail rapidly, until the patient becomes blind eventually.
How to carry out a preliminary self-examination :
High risk patients are recommended to carry out a preliminary self-examination with the Amsler grid :
- Place the grid 30cm away at eye level (wear appropriate glasses for near focus if you have presbyopia or refractive error).
- Cover the left eye with your hand and gaze steadily at the white spot in the centre of the grid with your right eye. (Repeat the step for the left eye).
- By keeping the eye still, you should check if there are any holes or distortion in the surrounding squares. If yes, see an optometrist for a thorough examination.
What treatments are available?
Ophthalmologists usually treat patients with photodynamic therapy or Anti VEGF to stop further degeneration by contracting the abnormal blood vessels on the retina. Moreover, These patients can also consume supplementary food that contain carotene/ Vitamin A/ lutein to prevent macular degeneration of the other eye.Examinations that can detect macular degeneration :
- Slit-lamp examination: An examination of the conjunctiva, the cornea, anterior chamber and lens.
- Intra-ocular pressure test: Testing internal pressure of the eyes. Normal intra-ocular pressure is between 10 and 21mmHg.
- Visual field test: The patient is asked to press a button when he/she sees a light. This test can detect disease of the macular and other optic nerves.
- Fundus Fluorescein Angiography (FFA): An examination of the retinal blood vessels such as the location of macular blood vessel proliferation and its seriousness.
- Ocular health examination: The patient is given eye drops to dilate the pupils.before the test. A focusing lens is used to check the macular and retina for bleeding, degeneration or diabetic retinopathy.
Jack Wong, Optometrist (Part 1)
PolyVision Eyecare (Mongkok) Centre