Asthenopia
Asthenopia is defined as fatigue, or overtiring of the eyes, and commonly known as eyestrain which can be caused by overuse of the eye structures (in particular – muscles). Often asthenopia is not a serious condition and can resolve by resting the eyes. Why are we even talking about it? Because with the development of our world into an electronics-driven society we are facing new problems with our body.
In this article:
- What is Asthenopia(eye strain)?
- Symptoms
- Causes
- Electronics
- Eye Muscles
- Why does this happen?
- Types of Asthenopia
- Diagnosis
- Risk Factors
- Prevention
- References
What is Asthenopia(eye strain)?
What do we do when we want to read? Well, before we would go to the library, pick up the book and sit down to flip pages reading the text. Now we open the phone or a tablet and stare into the screen.
Is there a difference when you use a computer screen or a real book? While we might think there is no difference at all, our eyes definitely see it differently. For example, when the page is flipping, it activates various accommodation muscles inside and outside of the eye to make sure the text image is placed exactly on the retina. The computer screen does not move anywhere, and it is flat. So, there is really no work on accommodation here. On the contrary, certain visual mechanisms might be overstrained because the image of the computer is pixelated and is far from the natural things we see around.
Symptoms
How do you know if the asthenopia affecting you? Having headache after spending 1 hour on Facebook talking to your friends? Or suddenly starting seeing double after taking 3-hour exam? Well, politics and relationships can give you’re a terrible migraine even without a phone screen. And hours of concentration and stress will cause dizziness of stars jumping around. You may have ocular asthenopia if you notice certain symptoms every time after an activity that requires precision of visual works:
Pain around the eyes or sore eyes
- Headaches
- Dry or watery eyes
- Blurred vision
- Sensitivity to light
- Nausea and/or vertigo
Often you will notice the onset of these symptoms after similar activities, such as studying for exam, or browsing news, or reading on the computer.
These symptoms tend to go away after you stop the activity and rest. As headaches and dry eyes are also common symptoms of the allergies, and can be a part of other eye diseases, it is important to realize of this happens any other time when you are not doing the activities.
Frequently other health problems come together with eye symptoms:
- Musculoskeletal: neck pain, back pain, shoulder pain, carpal tunnel syndrome
- Psychosocial: fatigue, poor sleep, depression
- Systemic: venous thromboembolism, shoulder tendonitis, and elbow epicondylitis
Causes
A common cause of asthenopia is too much screen time. Staring at a computer screen or digital devices for too long can bring on both eyes discomfort. In addition, staring at bright lights or trying to strain the eyes to see in poor lighting conditions can cause this condition as well.
Long periods of reading, driving long distances, generalized stress and fatigue, and eye exposure to dry moving air such as an air conditioner can also cause eye discomfort. How does it affect the eye? imagine that you are wearing shoes that are poorly made. It will cause foot discomfort, fatigue, muscle pain and eventually bad blisters. Our eyes are very sensitive to the moisture so they can move with high speed without being stuck under the eyelids. Also, the quality of the image changes if the cornea does not have the right lubricant over it.
It was also found that a certain light spectrum can over-activate retina cells that transmit image. As a matter of fact, even surrounding light is extremely important with very bright lighting almost poisonous to the eyes.
Electronics
Electronic is a very common culprit for today’s modern world and those with eye strain. It is recommended that we look away from electronic devices every twenty minutes just to give the eyes a rest. Because we blink much less often when staring at screens, are eyes can get dried out and irritated. In addition, electronics expose the eyes to frequent and excessive glare which cause increased ocular irritation. This condition can also be referred to as “digital eye strain” or “computer vision syndrome.”
Eye Muscles
There can be strain on the ocular muscles that contribute to asthenopia. The ciliary muscles (smooth muscle) and refractive error, the way in which your eye bends light, may play a role in accommodative asthenopia. In addition, there may be an imbalance of the extraocular muscles the surround the eyes.
Why does this happen?
Naturally, our body does not like to stay in one fixed position for a long time. Try to stand on one leg for an hour. You simply will get so tired that you will want to switch to another leg and stretch tired muscles. But while you are focused on a screen you “lock” your body signals and forget to switch posture and blink your eyes.
Overuse in the body will lead to fatigue, and the eyes are no exception. Ocular discomfort occurs because overuse stimulates the pain receptors on the eyelids, cornea, conjunctiva, or the uveal tract which then causes irritation, inflammation and pain.
Electronic devices such as computers, smart phones, and tablets emit blue light (400-490 nm) from their light-emitting diodes and produce electromagnetic fields, both of which interfere with the circadian rhythm.
Types of Asthenopia
Here are the types of eye fatigue by the mechanism that causes most problems:
- Accommodative asthenopia
- Photogenous asthenopia
- Muscular asthenopia
- Nervous asthenopia
There are certain conditions that specifically provoke eye fatigue:
- Mixed astigmatism
- Close viewing distance
- Upward gaze
- Dry eyes
- Lens flipper
- Small font
- Glare and flickering light
Diagnosis
You can easily suspect the asthenopia by noting when your symptoms occur and what helped to get rid of them. But sometimes, especially if these problems affect your child who cannot explain why the eyes hurt, it is important to see a doctor.
Diagnosis is usually set by an ophthalmologist who asks about the history and measures visual parameters. This diagnosis can change in certain cases when the visual measurements are off. It is possible you or your child developed nearsightedness or farsightedness, and that is why you are experiencing headaches and blurred vision.
Traditionally ophthalmic clinicians have considered asthenopia symptoms in children and young adults to relate to refractive error (both low and high degrees of hyperopia, and to some extent hyperopic astigmatism), given the accommodation/convergence triad and evidence that uncorrected hyperopia is often associated with excessive accommodative demand.
Dysfunctional accommodation and convergence may also induce ocular discomfort during prolonged periods of reading or attending to computers or handheld devices at near as is now the accepted norm for most young adolescent-aged individuals. Such prolonged near-work both at school and at home has also been independently reported to be associated with an increased prevalence of asthenopia symptoms that include headaches, psychological and head/neck muscular strain.
Risk Factors
Risk factors include those with preexisting eye conditions, those who wear eyeglasses, migraine sufferers, occupational requirement of frequent use of electronics, and excessive screen time.
Prevention
Now, when you know about what causes eye strain, you also can probably guess what can prevent it. Asthenopia can be prevented by:
- Frequent eye rest
- Taking breaks from looking at computers and digital screens
- Eye exercise and massage
- Reducing the brightness of the computer
- Choosing best computer monitors
- Ergonomic chairs and desks
- Proper lighting
- More exercise and outdoor activity
- Healthy organic diet and sufficient eye vitamins.
Eyestrain can also be prevented by filtering electronic with anti-glare products and anti-glare filters for eyeglasses. You can also prevent eyestrain by reading with adequate lighting or by improving poor air quality.