Find out what visual acuity is and how it affects your ability to see clearly. Learn about your measurement and the most common vision problems.

Visual acuity refers to the clarity and sharpness of a person’s vision. It is a measure of the eye’s ability to distinguish fine details and perceive objects clearly at different distances. Visual acuity is an essential aspect of visual function and is usually evaluated with an eye chart.

Visual acuity is a clinical measure that represents the resolving power of the eye.

Typically, visual acuity is represented by a fraction. The numerator indicates the distance at which the letter is seen on an eye chart, while the denominator corresponds to the distance at which the average eye can see the same letter clearly. For example, if a person has 20/20 vision, it means they can read the letters on an eye chart at a distance of 6 meters, which a person with normal vision should also be able to read at 6 meters.

1. A person with a visual acuity of 20/40 can see at 6 meters what a person with normal vision can see at 12 meters.
2. A person with a visual acuity of 20/200 can only see at 6 meters what a person with normal vision can see at 60 meters.

Visual acuity is usually influenced by various factors, such as the shape of the eye, the health of the cornea and lens, and possible alterations of the retina or optic nerve. Regular ophthalmological examinations play a crucial role in evaluating visual acuity and detecting any changes or abnormalities in order to provide appropriate interventions and treatments.

The Definition and Importance of Visual Acuity

Visual acuity is usually measured with a standardized eye chart known as a Snellen chart. This table consists of letters or symbols arranged in rows of decreasing size, with the largest ones at the top and the smallest ones at the bottom. A person reads the chart from a specific distance, usually 6 meters, and the smallest line of letters or symbols that she can accurately identify determines her visual acuity.

The Snellen table follows a specific way of expressing visual acuity measurements. Visual acuity is represented as a fraction, in which the numerator indicates the distance at which the test has been performed (normally 6 meters) and the denominator represents the distance at which a person with normal vision can read precisely the lineof letters or symbols. For example, if a person has a visual acuity of 20/40, it means that he can read at 20 feet what a person with normal vision can read at 40 feet.

Visual acuity is an essential component to diagnose and treat various eye conditions and refractive errors such as myopia, farsightedness and astigmatism. Its evaluation helps vision professionals to determine the proper prescription of glasses or contact lenses, evaluate the success of therapeutic interventions and control the progression of eye diseases. Periodic eye exams that include visual acuity tests are crucial to maintain optimal ocular health and detect possible vision problems at an early stage.

• A bad visual acuity can significantly impact a person’s ability to perform daily tasks, affecting their productivity and general wel l-being. It can hinder reading, driving, recognition of faces and even causing frequent headaches or visual fatigue.
• Good visual acuity allows people to have a clear and precise vision, which allows them to perform tasks with ease and precision.

How Visual Acuity is Measured

1. Snellen Table: The Snellen table is one of the most used tools to measure visual acuity. It consists of several ranks of capital letters, each of them of decreasing size. The person who undergoes the test stands up or sitting at a specific distance from the table and is asked to read the letters from the upper row down. The number that appears in the table indicates the distance at which a person with normal vision can read that concrete line with precision. Visual acuity is determined by comparing the person’s ability to read the table with what is considered normal.

Snellen table example:

2. Tumbling E: similar to the Snellen table, the Tumbling E table is designed for people who do not recognize or are not familiar with the alphabet. Instead of letters, this table uses the letter “E” revolved in different orientations. The person is asked to undergo the test that identifies in which direction the “E” is oriented, either upwards, down, to the left or to the right. The size of the “E” decreases from a row in a row, which allows to evaluate visual acuity.

3. Computerized visual acuity tests: With technological advances, computerized visual acuity tests are becoming more common. These tests involve the use of electronic graphs that appear on a screen. They offer various optotypes, including letters, numbers and symbols, which can be randomized and presented in different sizes. These tests provide standardized, easily adjustable options for accurate visual acuity measurements.

Factors that affect visual acuity

1. Refractive errors: Refractive errors, such as myopia, hyperopia and astigmatism, can significantly affect visual acuity. These errors occur when the shape of the eye prevents light from focusing directly on the retina, causing blurred vision. Corrective measures, such as glasses, contact lenses, or refractive surgery, can help people with refractive errors improve their visual acuity.

Refractive errors, such as myopia, hyperopia and astigmatism, can affect visual acuity causing blurred vision.

2. Age-related changes: As people age, their visual acuity tends to decrease. This natural process, known as presbyopia, affects the eye’s ability to focus on close objects. Presbyopia usually appears around age 40 and gradually worsens over time. Using reading glasses or bifocals can help counteract the effects of presbyopia and improve visual acuity for near tasks.

3. Eye conditions and diseases: Various eye conditions and diseases can affect visual acuity. Conditions such as cataracts, macular degeneration and glaucoma can cause a significant decrease in the clarity and sharpness of vision. Early detection, appropriate treatment, and regular eye exams can help identify and treat these conditions, thereby preserving visual acuity.

Eye conditions and diseases, such as cataracts, macular degeneration, and glaucoma, can cause decreased visual acuity.

Summary:

• Refractive errors, such as nearsightedness, farsightedness, and astigmatism, can cause blurred vision and affect visual acuity.
• Age-related changes, such as presbyopia, can cause a decrease in near vision as a person ages.
• Eye conditions and diseases, such as cataracts, macular degeneration, and glaucoma, can significantly affect visual acuity over time.

Understanding these factors and seeking appropriate care and treatment can help people maintain good visual acuity and ensure overall eye health.

Common vision problems related to visual acuity

A frequent vision problem related to visual acuity is myopia. Myopes have difficulty seeing distant objects clearly, but they can see close objects well. This condition occurs when the eyeball is slightly longer than normal or when the cornea (the transparent frontal surface of the eye) is too curved. Myopia can be genetic and tends to develop during childhood or adolescence. People with myopia can have blurred vision when they look at distant objects and may have to narrow their eyes or forge their eyes to see clearly.

Important information:

• Myopia is a common vision problem that affects a significant population worldwide.
• It can be corrected with glasses, contact lenses or refractive surgery.
• Periodic eye exams are important to control the progression of myopia and adjust the corrective measures accordingly.

Another vision problem related to visual acuity is farsightedness, also known as farsightedness. Unlike myopia, people with farsightedness have difficulty seeing nearby objects, while their vision from afar may not be affected. This condition occurs when the eyeball is slightly shorter than normal or when the cornea is flatter than usual. Freemetropia can also be genetic and be present from birth. People with farsightedness can suffer visual fatigue, headaches and blurred vision, especially when focusing nearby objects for a prolonged period.

Important information:

1. Children with farsightedness may not realize that they have a vision problem and can have difficulty reading and performing other tasks closely.
2. Glasses, contact lenses or refractive surgery can correct the farsightedness.
3. Periodic ocular exams are important to detect and control the farsightedness, especially in children.

Improving and Preserving Visual Acuity

There are several factors that can affect visual acuity, such as age, genetics and general health health. As we age, it is common for visual acuity to decrease, so it is more difficult to read small texts or see objects at a distance. However, there are various strategies and techniques that can be used to preserve and even improve visual acuity.

Periodic eye exams: programming regular eye exams with an optometrist or ophthalmologist is crucial to maintain good visual acuity. These professionals can early detect any underlying ocular condition or disease and provide adequate treatment to avoid greater deterioration of vision.

Proper lighting: adequate lighting plays an important role in visual acuity. When reading or works with the computer, it is essential to have sufficient lighting that is not too intense or too dim. Natural light or a wel l-placed desktop lamp can greatly improve visual clarity.

Healthy diet: Consuming a balanced diet rich in vitamins and minerals can contribute to improving eye health and visual acuity. Foods such as green leafy vegetables, carrots, citrus and fish contain nutrients such as vitamin C, vitamin E and omega-3 fatty acids that are beneficial to maintain good vision.

• Regular eye exercises: performing eye exercises can help strengthen eye muscles and improve visual acuity. Simple activities such as focusing distant objects, turning eyes in different directions and flashing regularly can help reduce eye voltage and improve visual clarity.
• Limit screen time: prolonged exposure to electronic screens can cause fatigue and eye tiredness, which negatively affects visual acuity. Take regular breaks, practice rule 20-20-20 (remove the view of the screen every 20 minutes and look at an object located 6 meters for 20 seconds) and maintain an appropriate distance to the screen can help reduce eye voltageand improve visual acuity.

Applying these strategies and incorporating healthy habits into daily life, people can actively work to improve and preserve their visual acuity, guaranteeing optimal ocular health and general wel l-being.

Visual Acuity and its Impact on Daily Life

One of the most used methods to measure visual acuity is the Snellen table, which consists of ranks of letters from different sizes. The table is placed at a standard distance, normally 6 meters, and patients are asked to read the smallest letters they can. The results are measured by a fraction, in which the upper number represents the test distance and the lower number indicates the distance at which a person with normal vision can see the same letters.

According to the American Academy of Ophthalmology, a visual acuity of 20/20 is considered normal.

A visual acuity of 20/40 means that a person can see at 6 meters what someone with normal vision can see at 12 meters. Visual acuity is usually measured for each eye separately and then jointly to evaluate binocular vision.

Visual acuity can be affected by various factors, such as refraction defects, eye diseases such as cataracts or glaucoma, and ag e-related conditions, such as presound. Periodic ophthalmological reviews are crucial to detect and treat visual deficiencies. People with bad visual acuity may need corrective measures such as glasses, contact lenses or even surgical interventions, depending on the underlying cause.

• Visual acuity is an essential measure of our ability to see fine details.
• A poor visual acuity can affect everyday activities such as reading, conducting and recognizing faces.
• Snellen’s table is a common method to measure visual acuity.
• The results are measured by a fraction, and 20/20 is considered normal.
• Visual acuity can be affected by various factors and require corrective measures.

1. Periodic ophthalmological reviews are crucial to detect and treat visual deficiencies.
2. To improve visual acuity, glasses, contact lenses or surgical interventions may be necessary.
3. Protecting our eyes and maintaining general ocular health is essential to preserve visual acuity.

When to Seek Professional Help for Issues with Visual Acuity

If you experience difficulties with your visual acuity, it is important that you know the signs that indicate the need for professional help. Some common symptoms that may indicate a decrease in visual acuity are:

• Blurred vision, especially from far or up
• Frequent ocular tension or headaches after reading or focusing objects
• Difficulty seeing clearly in low light conditions
• Greater sensitivity to glare and bright lights

It is essential to seek professional help if you notice any sudden or significant change in your vision, since it can be a sign of an underlying ocular condition or disease that requires an early intervention.

In addition to these symptoms, people with a family history of vision problems, such as myopia or astigmatism, should also consider the possibility of seeking professional help to make periodic eye reviews and evaluations of their visual acuity.

Visual acuity problems can significantly affect a person’s quality of life and hinder everyday tasks such as reading, conducting or recognizing faces. Therefore, it is essential to consult a vision professional, such as an optometrist or ophthalmologist, if he experiences persistent or worrying changes in his vision. Early detection and proper treatment can help prevent greater deterioration of visual acuity and guarantee optimal ocular health.

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Author of the article

Dr.Greenblatt M.

Medical oncologist at the Robert Larner College of Medicine, MD, at the University of Vermont