What are Refractive Errors?
Refractive errors are common visual problems that result in blurred vision. Myopia (short-sightedness), hyperopia (long-sightedness), astigmatism and presbyopia are the different types of refractive errors.
Refraction is the bending of light as it passes through one object on to another. Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then focused onto the retina. The retina converts light rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see.
Who is affected?
Refractive errors can affect both children and adults. However, it is important to detect refractive errors in children so as to avoid the development of lazy eyes.
Individuals who have parents with certain refractive errors may be more likely to get one or more refractive errors.
Types of refractive errors
1 Myopia (Short-sightedness)
Myopia is a type of refractive error where objects up close appear clearly, while objects far away appear blurry. With myopia, light comes to focus in front of the retina instead of on the retina.
2 Hyperopia (Long-sightedness)
Hyperopia is a type of refractive error where distant objects may be seen more clearly than near objects. However, people experience hyperopia differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant hyperopia, vision can be blurry for objects both near and far.
Astigmatism is a refractive error in which the eye does not focus light evenly onto the retina, which is the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out.
Presbyopia starts to affect most adults over the age of 40, when they progressively find it difficult to focus on near objects. This often impacts on activities like reading and knitting. This occurs when the natural lens gradually loses it elasticity as we age. It is this elasticity that permits multifocality in the eyes.
Spectacles and contact lenses are the most common visual aids used to correct refractive errors. However, due to convenience and safety issues, more people are turning to refractive surgery which includes ReLEx® SMILE, LASIK, PRK, implantable contact lens and refractive lens exchange.
Symptoms & signs
Blurred vision is the most common symptom of refractive errors. Other symptoms may include:
- Double vision
- Glare or haloes around bright lights
- Eye strain
- Poor night vision