A visual acuity test is designed to measure the sharpness or clarity of your vision and it’s usually one of the first tests taken during a comprehensive eye exam.
Visual acuity is also tested during eyeglasses or contact lens appointments, to evaluate changes in vision, to assess the results of LASIK and cataract surgery, or to assess the effects of an ocular disease.
The Snellen Chart
In general, most visual acuity tests use the Snellen chart.
The patient is asked to stand or sit 20 feet away from a chart that consists of 11 rows of capital letters which are carefully measured and presented. The letters decrease in size as you read down each row. The distance at which you first see all letters clearly is recorded as your visual acuity, or the “20/” number.
The Random E Test
The Random E test is another method of testing visual acuity. It is mostly used with children and adults who have trouble seeing letters.
During a Random E test, you will be asked to identify where the letter “E” is facing in the chart -up, down, left, or right. The doctor may project the chart or show it as a mirror reflection. You’ll be asked to look at the chart through a variety of different lenses till you can see the chart clearly. This helps your eye doctor determine your ideal eyeglass or contact lens prescription.
Understanding Your Results
Your visual acuity test result will come in the form of a fraction, such as 20/15, 20/20, or 20/40.
The top number is called a numerator, while the lower number is called a denominator. The numerator refers to the distance from which you are viewing the chart and the denominator refers to the distance at which someone with normal vision can read the line of letters or symbols.
If your score is 20/20 you can assume that you have normal visual acuity and you can see what most people that don’t need contacts or glasses can see when they stand 20 feet away from an object.
A 20/30, 20/40 result, or higher indicates that you aren’t able to see clearly far away, and you may need contact lenses, eyeglasses, or vision correcting surgery.
What You Need To Know About Vision Correction Surgery
Patients that need to wear eyeglasses or contacts, can choose to have vision correcting surgery.
The two most common types of vision correction surgery are LASIK and Refractive Lens Exchange (RLE).
LASIK is usually recommended to patients that are 21 – 40 years old, while Refractive Lens Exchange is ideal for people over 40 or those who are beginning to experience symptoms of presbyopia (difficulty seeing up close). These patients will benefit more from a refractive lens exchange procedure to correct their vision problems, such as myopia, hyperopia or astigmatism.
Both LASIK and RLE are safe and have incredible results. Your eye doctor will be able to guide you on which procedure is best for your specific eye care needs.
Visual acuity tests are used to evaluate your vision and determine if there is an issue. If you wear glasses or contacts, it’s important to have them checked every year to ensure that they are being properly fitted and that you aren’t experiencing any vision problems including blurred or distorted vision.