You may have heard your optician use such terminology as ‘astigmatism’, ‘myopia’, ‘hypermetropia’ and ‘presbyopia’. Not everyone understands what these terms mean. You should never be to afraid to ask your optician to explain a term you don’t understand but to help, below are some quick explanations of these common conditions.
Astigmatism is the optical term for more than one point of focus. It occurs when the surface of the cornea or crystalline lens is not spherical. Light from an object may focus on the retina in one direction but not the other. An astigmatic eye has curves that are steeper in one direction than the other, like a rugby ball. A normal, spherical eye has curves that are the same in all directions, like a football. A person with astigmatism will have distorted vision.
Myopia it is more commonly referred to as ‘short sightedness’. It is where the image is formed in front of the retina. This could be because the eye is too long, or the cornea or crystalline lens bends the light too steeply. A myopic person has blurred vision when looking at objects in the distance, and clearer vision when looking at objects close to them.
Hypermytropia is often referred to as ‘long sightedness’. It is where the image is formed behind the retina. This could be because the eye is too short, or the cornea or crystalline lens does not refract the light enough. A hypermetropic person has blurred vision when looking at objects close to them, and clearer vision when looking at objects in the distance.
With presbyopia, the elasticity of the lens is gone, causing light to be focused behind the retina.
This can lead to blurring and an inability to focus on objects close to the eye.
There are several classic symptoms associated with presbyopia: These include a need to hold books at arms length; difficulty focusing on small close objects; the need for brighter, direct light when reading; having to take off your glasses to see close objects (if you are short-sighted); fatigue, headaches or eye strain when reading.
The good news is that if you have any of these conditions, your optician should be able to correct the problem.
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.