Asthenopia is characterized by blurry vision and eye strain. People who spend a lot of time looking at screens often experience this problem. Fatigue is a common complaint of people who are using their phones or computer screens for an extended period of time. Since it's common, it's important to understand it so if you do experience it, you'll know what to do.

Why do our eyes feel tired after looking at screens for a long time?

Your eyes might feel sore or tired or achy if you are looking at a computer screen, phone, or television for a long period of time. In order to see up close, our eyes must converge and focus, and track what we're reading. It's a process that wears down the system over time, whether it's the physical eye muscles involved, or more commonly, it's the neurons. Both are factors that can affect how the brain processes information, its processing speed, and its processing power over time. 

What causes blurred vision (asthenopia)?

You eyes may start to see blurry, after using the computer or using the phone for a long time. There are usually two reasons for this.

Dry eye: It's either a case of dry eye. When we are looking at screens, our eyes blink less, and our blink rate drops. Blinking fully and frequently is a vital process that replenishes our tear film. So when we’re blinking less, our eyes are less moist, and when our eyes are less moist, and they don't have a robust tear layer, then they can see blurry. 

Eye teaming: When your eyes aren't teaming or focusing, the active process is disturbed. One of the things that your eyes or your brain can do when they get tired is create a system that can't function properly. Studies estimate that 25% of the population has convergence insufficiency, where our two eyes are not able to work together when focusing on an object at near, the primary complaint is blurred vision or double vision. The first symptom of a binocular vision system that is not working properly is blurry vision. So if you are having blurry vision while you're on the computer or on the phone or reading for a long time, it's a good idea to get checked out by a behavioral optometrist to find out why you're experiencing that symptom. 

What are the symptoms of blurry vision?

Asthenopia or blurry vision causes several other symptoms in addition to fatigue caused by eye strain. Some of these include:

• Burning or itching eyes
• Squinting
• Dry eyes
• Headaches, especially around the eyes and forehead
• Blurry or double vision
• Eye twitches
• Photophobia
• Difficulty concentrating

How is blurry vision treated?

The treatment will depend on the diagnosis. If the diagnosis of the cause of your blurry vision is dry eye, your optometrist will start you on a dry eye treatment program. If the cause is binocular vision issues then vision therapy will be the most effective treatment. 

Other tips include: 

• By simply giving your eyes a rest and taking care of them, your eye strain can be minimized and alleviated. We suggest the 20-20-20-20 rule. Every 20 minutes, take a 20 second break and look at a distance of 20 feet. Then firmly blink for 20 final seconds. 
• Additionally, you could try adjusting the brightness of your computer or phone screens, or adjusting the lighting in your room to prevent blurry vision.
• Eye strain can be mitigated by wearing the appropriate corrective lenses if it is being caused by something like farsightedness or nearsightedness. If you suffer from asthenopia due to dry eye, treating that condition should alleviate your eye strain.