Do you have difficulty reading road signs? Do you get headaches from reading a book or taking notes? If yes, you may be experiencing vision impairment due to a refractive error.
Causes of refractive errors occurs when the shape of the eye prevents light from focusing directly on the retina. This can be caused by many 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
Myopia
Myopia, also known as nearsightedness, is a common type of refractive error where objects close to the eye appear clear, but objects farther away appear blurry. Nearsightedness is extremely common.
Symptoms of nearsightedness
- People experience blurry vision when looking at faraway objects
- Eyestrain when trying to focus on distant objects
- Squinting to see far-off objects
- Headaches
Causes
Myopia occurs when the eye is slightly longer than normal or when the cornea, the clear front surface of the eye, has too much curvature. As a result, the light entering the eye is not focused properly on the retina, the light-sensitive tissue at the back of the eye, and the image of distant objects appear blurred. People with myopia can see things up close, but not at a distance. It is typically corrected with glasses, contact lenses, or refractive surgery.
Hyperopia
Hyperopia, also known as farsightedness, is a common type of refractive error where objects that are far away appear clear, but objects that are up close appear blurry.
Symptoms
- Difficulty focusing on objects that are up close, such as when reading or working on a computer
- Eyestrain or headaches after prolonged periods of near work
- Blurry vision at all distances
- Squinting to see objects more clearly
- Eye fatigue or discomfort
Causes
Hyperopia occurs due to the length of the eyeball being substantially shorter than usual. As a result, light rays entering the eye focus behind the retina rather than directly on it.
Astigmatism
Astigmatism is a type of refractive error that occurs when the cornea (the clear, front surface of the eye) is unevenly curved. This causes light to be focused at multiple points on the retina (the light-sensitive tissue at the back of the eye), resulting in blurry or distorted vision.
Causes
The most common cause of astigmatism is an irregularly shaped cornea, but it can also be caused by an unevenly shaped lens inside the eye. Astigmatism can be present at birth, or it may develop later in life due to certain health conditions, such as keratoconus (a condition in which the cornea becomes thin and cone-shaped).
Astigmatism is usually corrected with glasses or contact lenses that have a special lens curvature to counter the irregular curvature of the cornea. In conditions like keratoconus surgery may be required to stop the progression of irregular astigmation.
Presbyopia
Presbyopia is a condition that affects vision as people get older. Symptoms of presbyopia include difficulty reading small print, eye strain when doing close work, and the need to hold reading materials farther away to see them. Presbyopia is a natural part of the aging process and cannot be prevented, but it can be corrected with glasses or contact lenses that have a special lens power to help the eye focus on nearby objects.
Cause
It is caused by the loss of elasticity in the crystalline lens of the eye, which makes it difficult to focus on objects up close. Presbyopia typically begins to develop around the age of 40 and continues to progress with age.
It is very important to have regular eye checkups, especially if you have refractive errors. These conditions can affect your ability to see clearly and can lead to vision problems if left untreated. Regular eye exams can help detect these conditions early on, allowing for appropriate treatment to prevent further vision loss.
During an eye checkup, the doctor will perform a variety of tests to evaluate your vision and check for any signs of a refractive error. They may also check for other eye conditions and diseases, such as glaucoma, cataracts, and macular degeneration. It is important to follow the doctor’s recommendations for treatment and to have regular follow-up exams to monitor your eye health.
