Vision changes and problems can be caused by many different conditions. One of the most common conditions which is treatable is a refractive error.
A refractive error occurs when the shape of the eye prevents light from focusing directly on the retina. This can be caused by a number of things, such as the length of the eyeball being too long or too short, changes in the shape of the cornea, or a result of aging.
There are four types of refractive errors:
• Hyperopia
• Myopia
• Astigmatism
• Presbyopia
What is hyperopia?
Hyperopia, or farsightedness, is a refractive error that causes nearby objects to appear blurry while distant ones are clear. It is caused by the eyeball being shorter than usual. As a result, light rays entering into the eye focus behind the retina opposed to directly on it.
What is myopia?
Myopia is a refractive error that causes nearby objects to appear clear whilst distant ones are blurry. Near sightedness (myopia) is the most common refractive error and rates of myopia are increasing. In myopia, the eyeball is too long and hence light rays focus in front of
the retina.
What is astigmatism?
An eye with astigmatism will have light rays focusing at multiple points opposed to a single one. This causes vision to be blurred or distorted to some extent at all distances. It is caused by an irregularly shaped cornea.
What is presbyopia?
Presbyopia naturally occurs with age. Like hyperopia, presbyopia causes near vision to be blurry. It usually occurs after the age of 40. Presbyopia, in the absence of any other refractive error, can sometimes be treated with over-the-counter reading glasses. There is no way to slow down or reverse presbyopia.
Simple vision problems that are left untreated can spiral out of control and become more serious. Many eye diseases have no early warning symptoms or cause any early changes in vision. A detailed eye assessment is vital to pick up the cause for early changes in vision.
What are the signs that you may need glasses?
Aside from age ruining the “no glasses party”, there are some other warning signs you should be aware of. Simple vision problems that are left untreated can spiral out of control and become more serious. Here’s a list of warning signs you should watch out for that could indicate a problem:
- You have a hard time seeing objects both at a distance and up-close. This is a sign that you may have astigmatism.
- Blurred close-up vision, which can be a sign of hyperopia, also know as farsightedness.
- Objects at a distance are out of focus. This is usually diagnosed as myopia, or nearsightedness.
- Your eyes take longer to adjust from dark to light surroundings and vice versa.
- Your eyes don’t adjust to the dark at all and you have difficulty seeing at night.
- Squinting all the time, especially when reading, working with small objects or working in front of a computer.
- Painful eye strain or eye fatigue, especially when driving, watching TV and playing video games.
- Frequent headaches, especially when exposed to bright light.
- You see halos around light sources.
- You’re seeing double.
Having one or more of these symptoms doesn’t always mean you have an eye problem and need to wear glasses. Nonetheless, when you notice any of these symptoms, schedule an appointment with an optometrist immediately to ascertain what ails your eyes. Who knows, you might be lucky enough to add a fancy new accessory to your daily attire.
A refractive error can be diagnosed during a routine eye examination. Testing usually consists of asking the patient to read a vision chart while testing an assortment of lenses to maximise a patient’s vision. Special imaging or other testing is rarely necessary.
Refractive errors are commonly treated using corrective lenses, such as eyeglasses or contact lenses. Refractive surgery (such as LASIK) can also be used to correct some refractive disorders.
It is vital that you know the reason your vision is changing. If your vision changes as a result of a disease or disorder, delaying your eye exam could have severe and permanent consequences. A common and dangerous misconception is that if you are seeing well then you don’t need to have an eye exam.
Many eye diseases have no early warning symptoms or cause any early changes to your vision. An oculo-visual assessment by a licensed professional is the only way to truly know if your eyes are in fact healthy. And healthy eyes are the key to maintaining good site throughout life. On the other hand, if your vision changes are not due to an eye-health related issue, maximising your vision can go a long way to improving your quality of life and productivity: you won’t struggle to read the newspaper/computer screen, no more squinting to recognise faces or see road signs as you travel. It is important to note that an optometrist just doesn’t aim for 20/20 vision, but rather clear, comfortable binocular vision.
It is not uncommon for people who would benefit from vision correction to not even be aware of it. They have become accustomed to substandard vision as has slowly declined over time.
Dr Kavitha a/p Palaniappan
Consultant Ophthalmologist
MBBS (Manipal), MS (Ophthal) UKM
Pantai Hospital Ayer Keroh, Melaka
