6/6 Vision Explained
Have you ever wondered what perfect eyesight is? In optical terminology, it’s often referred to as 6/6 vision. Let’s take a deeper dive into what this means and whether it’s possible to achieve 6/6 vision.
Definition of 6/6 Vision and Visual Acuity
The phrase 6/6 vision means normal vision. As per medical journals, a person with 6/6 vision can see what an average individual can see the characters on a Snellen eye chart when they’re standing 6 metres away. An eye chart shows letters of progressively smaller size and helps in determining visual acuity, which refers to the clarity and sharpness of vision. Visual acuity is a static measurement of how accurately you can identify the characters on an eye chart; you are seated while you’re tested and the chart you’re viewing is stationary too. This is tested in high contrast conditions wherein the characters on the chart are black and the background is white. Comprehensive eye exams by an optometrist can help in diagnosing what’s affecting your ability to see clearly. Generally, an optometrist will prescribe eyeglasses, contact lenses, or a vision therapy program to aid in improving your vision. If your reduced vision is due to an eye disease, you may be prescribed ocular medication or another treatment.
Reading your Prescription
When you don’t have a prescription, nor do you require glasses or contact lenses for day-to-day tasks, you can assume that you have 6/6 vision. Dioptres are the unit of measurement used in prescriptions to measure refractive errors. In a prescription, a negative number would indicate that you are short-sighted, while a positive would show that you’re far-sighted. If you have a -1.00D prescription, it means that you can see objects at 1 meter clearly, while if you have a -2.00D prescription, you can only see objects clearly at half a meter. The higher your prescription number is, the more trouble you will have seeing clearly without eyeglasses or contact lenses. Read our detailed guide on reading prescriptions here.
How to Quantify Visual Acuity
Visual Acuity is quantified using Snellen fractions. This is coined after Herman Snellen, the Dutch ophthalmologist who developed this measurement system in 1862. The numerator is your distance in metres from the chart. The denominator is the distance at which a person with normal eyesight can read the same line.
This numerator’s distance is typically 6 metres. At this distance, the size of letters on the smaller lines close to the bottom of the chart follows a standard corresponding to “normal vision acuity” or 6/6 vision. If you can read these characters you have normal 6/6 vision acuity. The larger sizes on the chart correspond to poorer visual acuity measurements like (6/12, 6/18, etc). The largest alphabet at the top of most Snellen eye charts corresponds to 6/60 visual acuity, meaning very poor visual acuity. The smallest alphabets correspond to 6/3 vision. If you can read those characters, it means that your eyesight is twice as sharp as that of an individual with normal 6/6 vision.
For instance, when you are said to be having 6/12 vision, this means that your vision is poorer than average. At 6 metres distance, you can read letters that most people see from 12 metres. On the other hand, if you have 6/5 vision, it means that you can see a line in the eye chart at 6 metre’s distance while the average person can only see it when they are 5 metres away.
Whether you have 6/6 vision or not, it’s recommended to get eye exams as you age.
Drawbacks of Visual Acuity Testing
Even though it is possible to determine the relative clarity of eyesight in these standardized conditions, it’s not effective in predicting the quality of your vision in all situations. For example, it can’t help in predicting how well you would see the following:
- Objects which are as bright as their backgrounds
- Coloured objects
- Moving objects
There are three physical and neurological factors by which visual acuity can be determined. These are as follows:
- How accurately the cornea and lens of the eye focus light onto the retina,
- The sensitivity of the retinal nerves and the brain’s visual cortex,
- The brain’s ability to interpret information received from the eyes.
6/6 vision doesn’t however mean perfect vision, and it’s not very likely to happen. Other important factors such as peripheral awareness or side vision, eye coordination, depth perception, focusing ability, and colour vision play a part in your overall visual ability.
It’s essential to go for your eye tests regularly. Read more about the best intervals to get your eyes checked in this article. Eye tests can help in identifying deeper underlying problems such as glaucoma, macular degeneration, and even brain tumours.
What Deteriorates Visual Acuity and How to Improve It
Cataracts form when the lens tissue in your eye becomes cloudy and less flexible. This can make light rays scatter, or even stop them from passing through the lens in more advanced scenarios. Surgical removal or replacement with an artificial lens is the most appropriate option for restoring vision. With advancements in lens technology, some people no longer require even reading glasses after cataract surgery.
Refractive errors such as myopia, hyperopia, astigmatism, and presbyopia negatively affect visual acuity. As a result, visual aid intervention is needed with prescription eyeglasses and contact lenses. The goal of prescription eyeglasses is to bring a person’s vision to 6/6 visual acuity.
Are Eyeglasses needed if you have 6/6 VIsion?
Someone with 6/6 vision has normal eyesight with good clarity and sharpness. However, if you need to be on the computer for extended periods of the day, you may benefit from blue-light blocking glasses from zFORT®. Blue light is a potentially harmful form of light. While it is naturally emitted by the sun, electronic devices (which we’re spending progressively more time on every day) are also high-level producers. Blue light rays at a wavelength between 415nm - 455nm can damage your retinal cells, which may lead to premature eye ageing and vision problems in the future. Our exposure to these harmful light rays may also cause a range of other health problems, including poor sleep (according to a 2012 Harvard Medical School study).
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