If you are squinting to read the TV news headlines, or need to move a book close range to your face so you can distinguish the letters, you might be experiencing the first signs of nearsightedness.
You are not alone. Nearsightedness is one of the most common refractive error of the eye, and statistics show it has become more prevalent in recent years. About 30% of American adults suffer from it, and the next generation announces to be the most afflicted.
Everything You Need to Know about Nearsightedness
What is nearsightedness?
Nearsightedness is a type of refractive error where close objects appear clearly while objects in the distance remain blurry. The medical term is myopia.
Myopia occurs when the eyeball is too long, and the cornea and lens bend incoming light rays. Light then focuses in front, instead of on the direct surface of the retina.
The problem can also arise when the cornea and/or lens is too curved for the length of the eyeball.
What causes nearsightedness?
In the majority of cases, myopia comes about in childhood and continues to progress during growth spurts. In young adulthood, it can occur with increased up close tasks, like reading and computer use.
If the parents both suffer from nearsightedness, there’s a good chance the child will, too. So the majority of cases is genetic. Nowadays, other contributing factors can be doing work that involves focusing on close objects, excessive screen time, as well as too much time spent indoors.
Although the latter is still on the debate table, researchers claim that there’s a link between sunlight exposure and eye development.
All in all, the underlying cause of myopia seems to be a combination of all the factors of the above. Let’s take a closer look at each of them.
Near work cause
This hypothesis, also known as ‘use-abuse theory’, opposes the hereditary theory. Supporters blame near work time strains the eye and builds up a pressure conducive to myopia.
The visual stimuli theory agrees with all the other hypotheses that define myopia as the disease of the modern man. This statement is based on evidence showing that visual deprivation may cause improper growth trajectories of the eyeball.
The eye is genetically and evolutionarily predisposed to natural environments such as the jungle, the prairie, the ocean, and most of all, hunting.
Modern society has urbanized the environment, and eliminated certain activities from the initial calendar. Most humans now spend their time in artificially lit indoors, where the eye might have encountered ground for a new evolutionary direction.
Also, outdoor play and physical exercise have been correlated to lower rates in myopia. Not to mention the effect sunlight has on the production of retinal dopamine.
The sugar rush cause
One other risk factor for temporary myopia is the increase of blood glucose levels in the lens of the eye. The sugar alcohol that bags in the lens causes swelling, and temporary short-sightedness.
Nearsightedness Comes in Many Forms
Simple nearsightedness is the most common type, the causes of which we’ve discussed above. This condition is determined by an eye too long or too powerful for the cornea to stabilize incoming light properly.
In the most unfortunate cases, myopia can take a severe and progressive twist. Degenerative myopia, also called malignant or pathological myopia, is a cause of blindness.
Approximately 2 percent of Americans suffer from this condition. One symptom is bleeding in the eye caused by abnormal blood vessel growth.
This type is also known as twilight myopia. The name is only appropriate for a condition that is caused by the strain of the eye to let more light in during night time, a reflex which results in nearsightedness.
Normally, young adults can adjust the focus of their eyes at will, like the zoom on a camera. However, a dark environment messes up a system that clearly evolved for daytime use.
In the darkness, the eye focuses to a constant distance of about 1 meter.
Acquired myopia is the result of usage of diverse drugs, oxygen toxicity, nuclear sclerosis, and other anomalies.
Pseudomyopia, also knowns as false nearsightedness, comes about when the ciliary muscle is not relaxing properly. Its spasms, although transient, cause an increase in the refractive power of the eye, thus not allowing the lens to adjust properly.
Instrument myopia, sometimes called microscope myopia, occurs when someone is spending too much time looking into an instrument such as a microscope.
It installs over-accommodation, with a distance nearer than 6 meters putting pressure on the ciliary muscles to work harder than they actually need to.
Symptoms of Nearsightedness
- Blurry vision when looking at distant objects.
- Eyestrain and squinting to see clearly.
- Manifestations of night myopia.
- Fatigue when driving or playing sports.
Identifying nearsightedness early on in a child can make a difference. A child with myopia may exhibit certain visible signs indicative of the condition:
- Persistently squinting when reading.
- Seeming unaware of distant objects.
- Excessively blinking.
- Closing in on the television screen, iPad screen, or the classroom blackboard.
- Frequent rubbing of the eyes.
How to Correct Nearsightedness?
How can one correct nearsightedness? The most common methods are:
- Contact lenses.
- Refractive surgery.
- Eye exercises
The method you decide to employ pretty much depends on the degree or the severity of your myopia. You may need to wear glasses all the time or only when driving or watching the TV screen.
- Glasses and Contact Lenses
The first sign that you’re nearsighted will be registered on your eyeglasses or contact lens prescription. If you get a first number or sphere preceded by a minus sign, you have myopia. The higher the number, the worse the condition.
Then there are the night contact lenses for low to mild myopia. Orthokeratology, also nicknamed ortho-k, is a technique that uses what experts like to call night braces for the eye. These specially designed rigid gas permeable (GP) contact lenses reshape the eye to the contour of the cornea.
The effects are noticed in the morning when you remove the contact lenses. Your cornea will temporarily retain the new shape and you will be able to see clearly throughout the day without glasses.
This method works wonders for children who might be too young for LASIK or other refractive surgery types.
Fitting children with gas permeable contact lenses, progressive lenses, and bifocals doesn’t guarantee long-term results, but they might significantly reduce myopia progression.
Clinical studies have been underway in Auckland, New Zeeland to ascertain the effectiveness of ortho-k and myopia control soft contact lenses. The results have proved encouraging enough for researchers to promote the use of the dual-focus soft contact lenses.
- Refractive Surgery
The two most common procedures of refractive surgery, performed with an excimer laser, are LASIK and PRK.
LASIK, which stands for Laser-Assisted In Situ Keratomileusis, is a surgical method intended to reduce an individual’s dependency on contact lenses or glasses. Once performed, it permanently changes the shape of the cornea. The procedure involves creating a thin flap on the surface of the cornea, removing surplus corneal tissue, and returning the flap to its original position.
LASIK is the most common of refractive surgeries and used to correct other refractive errors such as hyperopia and astigmatism.
Short for photorefractive keratectomy, the PRK laser eye surgery corrects mild to moderate myopia, hyperopia, and astigmatism. So far, pretty similar to LASIK. The method employed, though, is slightly different.
During PRK surgery, the laser delivers a cool pulsing beam of ultraviolet light on the surface of the cornea, not underneath a flap like in LASIK surgery. The eye surgeon will then remove the layer of tissue which flattens the cornea, thus permitting the light rays to properly focus on the retina.
Phakic IOLs, or intraocular lenses, are the alternative to LASIK and PRK eye surgery. In some cases, it has even been reported to have produced better and more predictable results than in laser refractive surgeries, particularly in the case of individuals with thinner-than-normal corneas.
These lenses are called phakic because the eye’s natural lens is left untouched, unlike the intraocular lenses used in cataract surgery, for example.
Phakic IOLs work like permanent contact lenses which have been surgically placed within the eye. No special maintenance is needed.
- Eye Exercises
The eye is a muscle, which means it has to be worked out regularly to keep fit. Remember when we noted the lack of physical exercise as one of the causes for myopia.
If you don’t suffer from hereditary myopia, yoga for eyes can actually be beneficial to your future eye vision. Some of the methods include the eye-finger exercise, the focus-on-a-pencil exercise, and room scanning.
Eye exercises can be effective for:
- Reducing eyestrain.
- Reducing sensitivity to light.
- Increasing eye power, peripheral vision, and depth perception.
- Helping the eye to focus better.
If the problem is left untreated, nearsightedness could become a global epidemic for the next generation. Tackling myopia long-term should be a priority both for researchers, as well as for concerned parents.