Joel Hunter, MD Refractive Surgeon, Hunter Vision Updated 04/01/21 3:16 PM
When talking about visual acuity, it doesn’t come as a surprise to hear that 20/20 vision is the benchmark of what it means to have good eyesight. In pursuit of that goal, we’ve all experienced being told by mom and pop to eat the carrots on our dinner plate, go to sleep early, and avoid reading in low light to avoid eye strain.
But anyone who visits an eye specialist finds out that the biggest factor in declining vision is inevitable. It’s having birthdays. Aging can be a strong factor why visual acuity changes aside from eye diseases and poor nutrition (no matter how many carrot sticks you eat).
In my earlier post, I wrote a long discussion on 20/15 vision. But, in the pursuit of fulfilling my passion to help my readers in this blog to get to know more about visual acuity (okay, I may be exaggerating here but seriously, I feel happier when writing about eyes), I’m writing about 20/80 vision.
Recently, I’ve had some folks requesting that I write about 20/80 visual acuity. My initial question was, “why 20/80? Why not 20/100? Or 20/200?” And the answers kept coming in: they have 20/80 vision; their teenage son has the same eye prescription; they’re curious about the size of the letter “E” on the eye chart in the doctor’s office (okay, that last one is made up).
What is 20/80 Vision?
When one has 20/80 vision, this means that his or her eyesight is already in the low vision range, specifically, it’s moderate visual impairment as determined by the International Council of Ophthalmology (ICO). Some eye doctors may state your visual acuity instead as 0.25 (this is just the same as 20/80 but stated in decimal notation) or 4.0 in terms of visual angle.
So what does this mean? In the interpretation of the ICO, the visual impairment still more functionality compared to someone with a 20/200 vision, who’s already in the severe visual impairment range.
With this condition, low vision is evident but not to the point where the patient is legally blind. For a better comparison, let’s use the size of an average newsprint, which is measured as 1 M. For the sake of those who don’t have any idea what a 1 M is, the Sloan M system is used to measure letter size in a reading chart. It was first introduced by Louis Sloane in the American Journal of Ophthalmology in 1959 and has been used as a standard by the Committee on Vision of the U.S. National Research Council ever since.
It’s a letter or number used in testing visual acuity (or what’s often called an optotype in medical parlance). To make the explanation less complicated, the M-unit is related to a fixed 1-meter distance when one of the letters in Sloane’s reference standard subtends a visual angle of 5 min of arc (a unit of angular measurement). In other words, research tells us that 1 M is similar to the average size of a newsprint as stated in a published research.
Obviously, as visual acuity becomes weaker, one reads much better at a shorter distance (usually with the help of reading glasses). Generally, newsprint is read clearly at a distance of 40 cm. Since for a 20/20 vision, 1 M is read at 100 cm, then reading small print is much easier.Whereas if the patient has 20/80 vision, 1 M is read at 25 cm so patients have to use strong lenses to read clearly, or -- if they are near-sighted -- hold the paper much closer to the eyes compared with someone with 20/20 vision.
What do the numbers in 20/80 visual acuity mean?
Each time you have your eye exam, the doctor asks you to stare at the Snellen chart and to read the letters. Ideally, you should be 20 feet away from the chart and you’d start reading from the top where the big letter “E” reigns over the other letters that get smaller and smaller as you move down the rows.
If you have 20/80 vision, then you have stopped reading at the third row where you found the letters T, O and Z readable. What does this mean?
Simply put, you must be 20 feet away from an object to see it properly compared to someone who can do the same at an 80-foot distance. So, when you pass by a newspaper stand (this may be an old-fashioned example), the headlines are visible but the rest of the text on the front page won’t be clear enough unless you’re wearing your eyeglasses or contact lenses.
Is this normal? You might not have 20/20 vision and that’s okay because perfect visual acuity is rare, especially for those who are into their adulthood. The World Health Organization (WHO), in fact, states that 1.3 billion people suffer from some sort of vision impairment.
In addition, having 20/20 visual acuity does not mean one has perfect vision. That’s because you may see things clearly at a distance of 20 feet but would feel uncomfortable when you’re too close to it. The National Institutes of Health discovered that as low as 35 percent of adults have 20/20 vision without their glasses or contact lenses on or have undergone eye surgery. That’s how few people have the “standard” for vision acuity.
Does it mean a patient with 20/80 vision is legally blind?
In the United States, a person is considered legally blind if his or her vision on his best eye cannot be corrected any better than 20/200, or if his or her visual field (what is seen without moving the eyes from side to side) is limited to only 20 degrees or less. This serves as the basis for someone to receive the appropriate disability benefits.
So if your vision is still at 20/80, then you are not considered legally blind by definition. Remember, however, that visual acuity does not fully indicate if a person has vision problems. You may have better vision than 20/80 but still find performing daily activities much more difficult than someone with a poorer visual acuity.
Can I still drive with a 20/80 vision?
This depends on the state regulations where you’re planning to get a license. Here in Orlando, Florida (where we get lots of vacationers driving to Cinderella’s castle or to other family destinations almost every day), the Department of Motor Vehicles requires those who apply for an original or renewal driver’s licenses to have “20/40 with both eyes tested together and 20/40 in one eye and at least 20/70 in the other eye.”
If you don’t meet the requirements, you are allowed to wear eyeglasses or contact lenses so that you can achieve the minimum visual acuity required.
If you have 20/80 vision for both eyes, even with correction, then the state won’t allow you to drive.
If you want to know more about visual acuity requirements in your state, you may refer to the guide prepared by the American Academy of Ophthalmology.
What factors cause visual acuity to change to 20/80?
Visual acuity often decreases as we age. You may not need eyeglasses or contact lenses now but at some point, your eye doctor may tell you it will help you to start wearing them. As you reach your 60s, the risk of having advanced presbyopia increases along with the presence of floaters. More so, women at their menopausal stage are more likely to experience dry eyes, which also leads to problems with visual acuity.
Age-related factors that can affect visual acuity and result in low vision according to the American Optometric Association (AOA) include smaller pupil size, absence of peripheral vision, macular degeneration, glaucoma, traumatic brain injury, and detachment of the retina.
Can 20/80 vision still be corrected?
Getting your vision corrected is possible (although it cannot be guaranteed 100 percent as with any medical procedure conducted). Your doctor may ask you to use eyeglasses or contact lenses. A long-term solution, however, may be corrective surgery.
New forms of eye treatment technology can produce results close to 20/20 vision as explained by the medical practitioner in this interview conducted by the American Academy of Ophthalmology. Light adjustable lenses and other advanced intraocular lenses used to treat cataracts are used to help patients achieve better vision.
But a more well-known procedure that you’ve probably heard of is LASIK, that helps achieve the goal of restoring a patient’s vision to 20/20 or better if possible. If you’re a good candidate for this treatment, then your expectations for improvement can be based on pre-operative testing. In my earlier post, I’ve mentioned that the results you’ll achieve can be different from others. I often tell my patients before undergoing LASIK that they should anticipate to see as well as their eyes can see, but not better than that. They should also be able to get rid of their eyeglasses or contact lenses.
And then there are alternatives besides LASIK: PRK, ICL, RLE, and refractive cataract surgery are some of the procedures that I recommend to patients depending on their condition.
The point here is that LASIK should be performed to correct vision up to a level to keep a patient comfortable and highly satisfied.
Is LASIK for 20/80 vision affordable?
If you’re keen on getting your vision to normal level, your first question might be the same question that almost all of my patients ask: Can I afford LASIK?
But the question as to how much LASIK is won’t get you to the answer that you really need. Rather, it’s important to consider this: will the benefits of LASIK be something that is worthwhile in the long-term? Most people who get LASIK regret not doing it earlier, as I wrote in my earlier post.
Yes, LASIK can be expensive but that doesn’t mean that it’s not a wise personal investment. I do understand that paying out-of-pocket is something that most patients are not ready to do so here at the clinic, we’ve made it easier for our patients to achieve better vision.
The good news is that eye surgery cost in Orlando, Florida is now more affordable with a payment plan tailored to your tight budget.
At Hunter Vision, we fully understand the value of taking care of your eyes with or without the expensive procedures. You get expert care from some of Florida's best eye doctors BUT without asking you to dig a hole in your pocket through our payment plan.
Where to get LASIK in Orlando, Florida
Your eyes are too important to try to save a few dollars. Go somewhere that charges enough for you to be comfortable throughout the process.
Author: Joel Hunter, MD is an Ophthalmologist, Refractive Surgeon, and the Founder of Hunter Vision, a LASIK Orlando Clinic in Florida.