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Refractive Error

A defect in the focusing of light on the retina.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Refractive Errors

Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. The length of the eyeball (longer or shorter), changes in the shape of the cornea, or aging of the lens can cause refractive errors.

What is refraction?

Refraction is the bending of light as it passes through one object to another. Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see.

What are the different types of refractive errors?

The most common types of refractive errors are myopia, hyperopia, presbyopia, and astigmatism.

More about Refractive Errors NIH - National Eye Institute

What works? Research summarized

Evidence reviews

Corneal refractive surgery and phakic intraocular lens for treatment of amblyopia caused by high myopia or anisometropia in children

OBJECTIVE: A systematic review of literature was performed to compare various visual function parameters including the final visual acuity outcome and/or adverse events between corneal refractive surgery (CLRS) and phakic intraocular lens implantation (p-IOLi) in the treatment of refractive amblyopic children.

Screening for Visual Impairment in Older Adults: Systematic Review to Update the 1996 U.S. Preventive Services Task Force Recommendation [Internet]

Impaired visual acuity is common in older adults. Screening for impaired visual acuity in primary care settings could identify older adults who are unaware of or do not report vision problems, and lead to interventions to improve vision, function and quality of life.

Glaucoma: Diagnosis and Management of Chronic Open Angle Glaucoma and Ocular Hypertension

This guideline covers adults (18 and older) with a diagnosis of chronic open angle glaucoma or ocular hypertension and those with chronic open angle glaucoma or ocular hypertension associated with pseudoexfoliation or pigment dispersion. In addition, the guideline will cover populations who have a higher prevalence of glaucoma and may have worse clinical outcomes including people with a family history of glaucoma, younger people (<50 years) and people who are of black African or black Caribbean descent. Options for pharmacological, surgical, laser and complimentary or alternative treatments are considered in terms of clinical effectiveness and cost effectiveness.

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Summaries for consumers

Amblyopia in children: Overview

In some children one eye is favored by the brain because it provides a better image. If this happens, the other eye is neglected from childhood on, and it does not get the chance to fully develop. This is known as amblyopia or “lazy eye.”

Amblyopia in children: Treatment options for amblyopia

There are different options for treating amblyopia in children, mostly depending on the type and severity of the condition.Some children only have one eye that focuses properly. This is known as amblyopia or "lazy eye" and is caused by the eyes sending two different images to the brain, which can happen when a child has strabismus (a squint) or is more nearsighted or farsighted in one eye than the other. The brain then ends up preferring the information coming from the stronger eye and neglecting the other.The severity of amblyopia largely determines the kind of treatment needed. The standard treatment options are:Glasses to correct refractive errors (nearsightedness or farsightedness, distorted vision).Eye patching (occlusion therapy): The stronger eye is covered with an eye patch for several hours a day. Children who wear glasses can fit the patch over one of the lenses. This is done to encourage the weaker eye to work harder so that vision improves. The word occlusion comes from Latin and means "closed."Drug therapy: Eye drops containing atropine or a similar drug are used to temporarily blur vision in the "good" eye. They relax the muscles in the eye so that the lens will not focus for a few hours.

Treatment of amblyopia (lazy eye) caused by strabismus (squint) with patching or optical treatment (glasses or penalisation) or both

Review question: Treatment of amblyopia (lazy eye) caused by strabismus (squint) with patching or optical treatment (glasses or penalisation) or both.

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Terms to know

Astigmatism
A disorder of the vision, usually due to a misshapen cornea, such that light does not focus correctly on the retina causing a blurred image.
Cornea
The transparent part of the eye that covers the iris and the pupil and allows light to enter the inside.
Hyperopia (Farsightedness)
A disorder of the vision where the eye focuses images behind the retina instead of on it, so that distant objects can be seen better than near objects.
Lens
Myopia (Nearsightedness)
The condition in which the individual does not see far distances clearly.
Presbyopia
Presbyopia is a slow loss of ability to see close objects or small print. It is normal to have this as you get older. People with presbyopia often have headaches or strained, tired eyes. Reading glasses usually fix the problem.
Retina
The light-sensitive tissue lining at the back of the eye. The retina converts light into electrical impulses that are sent to the brain through the optic nerve.

More about Refractive Error

Photo of a young adult

See Also: Comprehensive Dilated Eye Examination

Other terms to know: See all 7
Astigmatism, Cornea, Hyperopia (Farsightedness)

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