Refractive errors are the most common vision problems. These include myopia, hyperopia, and presbyopia. These problems arise when the shape of the eye hinders light from focusing directly on the retina. Refractive errors can be caused by changes in the shape of the cornea, length of the eyeball or aging of the lens.
Refraction and Vision
Refraction refers to the bending of light which occurs when the light is passing through one object to another. The refraction of light as it passes through the cornea and the lens brings about vision. This light is focused on the retina. Once the light hits the retina, it is converted into messages that are then transmitted to the brain through the optic nerve. The brain interprets the signals into images.
Vision problems arise when the light is not focused directly on the retina. These problems mainly affect people above the age of 35. The signs and symptoms of vision problems include haziness, double vision, eye strain, headaches, squinting and glare around bright lights.
The common vision problems (refractive errors) are discussed below.
Myopia
This is a refractive error in which close objects appear clear but objects that are farther away appear blurred. It is also referred to as nearsightedness. This problem occurs when the eyeball is too long. This leads to light focusing at a point in front of the retina, instead of directly on it. This results in blurry vision.
Myopia affects approximately 30% of Americans, according to the American Optometric Association. This condition is mainly diagnosed between the ages of 8 and 12. At this age, the eyes are growing and thus the shape of the eye can change. Visual stress has also been linked to the development of this condition.
The signs of this condition include pain in the eyes, headaches, squinting and blurry vision for faraway objects.
Myopia can be treated through:
• Corneal refractive therapy.
• Refractive surgery: This involves reshaping the cornea to ensure it focuses light directly on the retina.
• Corrective lenses: These include contact lenses and glasses. These work to shift the focus of light as it enters the eye, focusing it directly on the retina.
Hyperopia
This is a condition in which one can clearly see objects that are far away but have blurry close-up vision. It is also known as farsightedness. Hyperopia occurs when light is focused behind the retina. It occurs when the eyeball is too short or when the lens or cornea has an abnormal shape.
This problem affects about 5-10% of the US population, according to the National Eye Institute. The signs of this condition include blurry vision for close objects, headaches, and squinting.
Hyperopia can be treated through:
• Eyeglasses and contact lenses: These change the way light enters the eye, providing better focus.
• Refractive surgery: Involves changing the shape of the cornea to provide better focus. However, this is not as safe as wearing glasses as it may bring about various complications.
Presbyopia
This is a condition in which one is not able to focus up close. This vision problem is brought about by aging. As one ages, the natural lens in the eye hardens. This prevents light from focusing directly on the retina. Also, the muscle fibers around the lens are affected, making it difficult to focus in up close objects.
Signs of presbyopia include difficulty reading small print, eye strain, headaches and problems seeing close objects. These signs are mainly experienced by those above the age of 40.
Presbyopia can be treated through:
• Non-prescription lenses: if approved by your optometrist
• Prescription lenses: This is the next option if non-prescription lenses fail. Visit an optometrist for the most appropriate lens.
• Surgery.
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