Visual impairment is recognized as one of global significant health problems which have a serious impact on the personal, economic, and social life of an individual. Globally, there are at least 2 billion people who suffer from visual impairment and almost half of these cases could have been addressed and prevented.

Many people can be affected by visual impairments including young children, with causes such as uncorrected refractive errors, cataract, glaucoma, diabetic retinopathy and many more. In this post we will be looking at types of refractive errors including their common causes and possible ways to prevent them.

What are refractive errors?

Refractive error of the eye is a very common vision problem where the shape of the eye keeps light from focusing on our retina, which is a light sensitive layer of tissue in the back of our eyes. This will prevent us from being able to see clearly and focus on the images from the outside world, resulting in blurred vision.

What are the types of refractive errors?

There are four major types of refractive errors, which are: 

• Short sightedness, also known as myopia, where close objects are clear but distant objects look blurry. Usually, short sightedness is inherited and often discovered during childhood and it will progress throughout adolescence. Even though short sightedness usually starts in children, it can affect adults as well.
• Long-sightedness, also known as hyperopia. In contrast to myopia, hyperopia makes nearby objects look blurry. Hyperopia can also be inherited. Children often have hyperopia, which may lessen in adulthood.
• Presbyopia. Presbyopia happens due to the aging of lenses in the eye, which affect middle-aged or older adults. The lens is more rigid and less flexible, losing its ability to focus images on the retina. Presbyopia causes a person to have trouble seeing things at close range and this is a normal part of aging.
• Astigmatism. Symptoms of astigmatism are blurry and distorted vision. The clear front layer of our eyes known as cornea is usually smooth and equally curved in all directions. When light enters our eyes through the cornea, it is focused equally on all planes or in all directions. People with astigmatism will have cornea or lenses that are having different shapes than normal resulting in distorted images formed.

Most people will experience one if not more, of these conditions in their lifetimes. 

What are the symptoms and signs of refractive errors?

Blurred vision is the most common symptoms of refractive error, while some people may also experience symptoms such as:

• Double vision 
• Squinting 
• Headaches 
• Feeling tired and sore of the eyes 
• Trouble focusing especially looking at computers 
• Reduced concentration 

However, some people might suffer from refractive errors without even knowing it as they do not have any symptoms. Refractive errors can be detected by an eye care professional during regular eye examination therefore it is important to get eye exams done regularly and start treatment as early as possible. 

What are the risks and causes of refractive errors? 

Several groups of people are more likely to be affected by refractive error such as those with family history of refractive errors and aging. There are also a few environment factors that will increase the risk of refractive errors as well, such as:

• Long periods of work in front of a digital screen, which will increase digital eye strain. 
• Spending long hours indoors with inadequate sun exposure. 
• Inadequate regular sleeping hours. 

The main cause of refractive error is due to the inability of light to focus on our retina and form a clear image, and there are three main factors that affect this focusing ability: 

• Aging of the lens in the eye that loses flexibility to focus light onto retina.  
• Eyeballs that are too short or too long to focus light properly. 
• Abnormalities in the shape of the cornea resulting in distorted images. 

How to prevent refractive errors? 

Although refractive errors of the eye cannot be prevented, it can be managed well through early diagnosis via eye examination. Treatment options may include: 

• Wearing glasses. Prescription glasses are the safest and simplest way to correct your vision. 
• Wearing contact lenses. These are worn directly on the eyes to correct your sight, which are more practical while undergoing physical activities as compared to prescription glasses. 
• Undergo laser eye surgery. Laser eye surgery can reshape the shape of our cornea and make vision clearer. 
• Undergo intraocular surgery. This type of eye surgery involves an implant of intraocular lens, which is a thin plastic that replaces our natural lens. This new artificial lens is shaped perfectly and will remove any refractive errors. 

See your doctor for eye exams regularly and inform your doctor if your vision gets worse even after treatment. Eating healthily, including the right type vitamins and minerals such as Lutein, fish oils, and  Bilberry that are good for eye health may also help in your eye care.  Also, minimizing screen time to reduce digital eye strain are good habits that should be practiced to maintain eye health as well.  

Reference

1. Refractive errors. Refractive Errors | Kellogg Eye Center | Michigan Medicine. (n.d.). Retrieved August 12, 2022, from https://www.umkelloggeye.org/conditions-treatments/refractive-errors
2. Refractive errors: Types, signs, causes, and treatment. MyVision.org. (2022, February 26). Retrieved August 15, 2022, from https://myvision.org/eye-conditions/refractive-errors/
3. U.S. Department of Health and Human Services. (n.d.). Refractive errors. National Eye Institute. Retrieved August 13, 2022, from https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/refractive-errors