Refractive Errors

Overview

Refractive errors are conditions where the shape of the eye prevents light from focusing correctly on the retina, the light-sensitive layer of tissue at the back of the eye.

Eye doctors can prescribe eyeglasses or contact lenses to help people with refractive errors see clearly.

Types of Refractive Errors

Nearsightedness (Myopia)

The most common symptoms of nearsightedness include:

• Trouble seeing things that are far away
• Needing to squint to see clearly
• Eye strain — when the eyes feel tired or sore
• Some people with nearsightedness get headaches, though this is less common. People with mild nearsightedness may not notice any symptoms.

Nearsightedness happens when the eyeball grows too long from front to back, or when there are problems with the shape of the cornea or lens. These problems make light focus in front of the retina instead of on it. Anyone can be nearsighted, but the risk is higher for people with family members who are nearsighted. Nearsightedness usually starts between ages 6 and 14 and gets worse until the early twenties. 

People with severe nearsightedness may be at higher risk for other eye conditions, like retinal detachment which occurs when the retina is pulled away from its normal position.

Farsightedness (Hyperopia)

The most common symptoms of farsightedness include:

• Trouble seeing things up close
• Eye strain
• Headaches, especially when reading

People with mild farsightedness may not notice any symptoms.

Farsightedness happens when the eyeball grows too short from front to back, or when there are problems with the shape of the cornea or lens. These problems make light focus behind the retina instead of on it. A person is more likely to be farsighted if other family members are farsighted.

Astigmatism

The most common symptoms of astigmatism include:

• Blurry vision
• Needing to squint to see clearly
• Headaches
• Eye strain
• Halos and glare around lights at night

People with mild astigmatism may not notice any symptoms.

Astigmatism happens when the cornea or lens has a different shape than normal. Doctors do not know what causes astigmatism, and there is no way to prevent it. Some people are born with astigmatism, but many develop it as children or young adults. Some people may also develop astigmatism after an eye injury or eye surgery.

Presbyopia

Presbyopia is the age-related loss of near focusing ability, usually beginning in the early to mid 40s. Symptoms of presbyopia include:

• Trouble seeing things up close
• Needing to hold reading materials farther away to focus on them
• Eye strain
• Headaches

Presbyopia gets worse over time, but it usually stops getting worse after age 65.

As a person ages, the lens in the eye gets harder and less flexible, and it stops focusing light correctly on the retina. This makes nearby objects look blurry. Presbyopia is different from farsightedness, another refractive error that also makes it hard to see things up close.

Diagnosis

Refractive errors can be diagnosed by a simple, painless eye exam. Regular eye exams are important because people with mild refractive errors may not notice any symptoms. This is especially true for children, who may be less likely to realize their vision is not normal.

Treatment and Management

The most common treatments for refractive errors are eyeglasses or contact lenses. Doctors can also use surgery to treat refractive errors in adults. Surgery can change the shape of the cornea so it can focus light correctly.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on refractive errors.

Find Treatment

An eye doctor can perform an eye exam to check for refractive errors and prescribe the right treatment.

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH supports research on the causes, prevention, diagnosis, and treatment of eye disorders.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.