Refractive Errors
Source: MedlinePlus Health Topics, U.S. National Library of Medicine
What are refractive errors? The cornea and lens of your eye bend (refract) light rays to focus them on the retina. Refractive errors happen when the shape of your eye prevents light from focusing correctly on the retina. This causes blurry vision. Changes in the eye's shape affect how light rays bend and focus, leading to vision problems. What causes refractive errors? Refractive errors can happen when: The eyeball is too long or too short. The cornea changes shape. The lens becomes less flexible as you age. Each type of refractive error is different, but they all make it hard to see clearly. What are common refractive errors? Four common types of refractive errors include: Nearsightedness (myopia) , blurred vision when looking at faraway objects. Farsightedness (hyperopia) , blurred vision when looking at close-up objects. Astigmatism , blurred or distorted vision at all distances, which can make night vision harder. Presbyopia , difficulty seeing things up close because the lens becomes less flexible with age. It affects adults in middle age and older and often begins around age 45. Who is at risk for refractive errors? Anyone can have refractive errors. It's the most common type of vision problem. You may be more likely to have one if other family members wear glasses or contact lenses . Most types of refractive errors start in childhood or are present at birth. Presbyopia is different. Nearly everyone develops it as they age, typically starting around age 45. What are the symptoms of refractive errors? Sometimes you may not notice vision changes right away, which is why regular eye exams are so important. The most common symptom is blurred vision. Other symptoms may include: Double vision Haziness Glare or halos around bright lights A need to squint to see clearly Headaches Eye strain or tired eyes Difficulty focusing when reading or using a computer If you already wear glasses or contact lenses and notice these symptoms, you may need a new prescription. Tell yo