Category: Education

Posted on

Computer Vision Problems

Computer vision problems or Digital eye strain is a group of eye and vision problems. The problems can include eyes that itch and tear, and are dry and red. Your eyes may feel tired or uncomfortable. You may not be able to focus normally. These problems are caused by lots of computer or digital device use. Using e-readers and smartphones may also cause these problems.

These problems have been increasing in frequency over the past few decades. Many people have some symptoms if they use a computer or digital device for long periods. Most computer or digital device users have symptoms at least some of the time. Digital eye strain is very common in both children and adults.

What causes digital eye strain?

For many reasons, reading text on a computer screen or digital device is often harder for the eyes than reading printed text. This is why working on a computer for a few hours may cause symptoms of digital eye strain, but reading a book may not.

Several factors help to cause digital eye strain, such as:

  • Screen glare
  • Poor lighting
  • Poor posture while using a computer
  • Viewing a computer at the wrong distance and angle
  • Uncorrected vision problems
  • A combination of many of these factors

People often blink less when using a computer than when reading printed text. This can cause dry eye, This may contribute to digital eye strain.

Who is at risk for getting digital eye strain?

You may be at greater risk for digital eye strain if you:

  • Spend a few hours or more a day at a computer or on a digital device
  • Are too close to your computer or digital device screen
  • View your computer or digital device at the wrong angle
  • Have bad posture while using your computer or digital device
  • Have eye problems (even minor ones) not corrected with glasses or contact lenses
  • Have a pair of glasses that is not suitable for viewing the distance of your computer
  • Don’t take breaks while you are working

You may have an underlying problem with dry eye. This may make digital eye strain worse, or more likely to occur. Dry eye is more common in women than in men. It also becomes more common with age. Some medicines and health problems make dry eye more likely. For example, if you use antihistamines, you may be at greater risk of having dry eye. If you have thyroid disease or certain autoimmune diseases, you are also at greater risk of having dry eye.

What are the symptoms of digital eye strain?

Digital eye strain can cause many symptoms, including:

  • Blurred vision
  • Double vision
  • Dry eye
  • Eye discomfort
  • Eye fatigue
  • Eye itching
  • Eye redness
  • Eye tearing
  • Headaches
  • Neck and shoulder pain

Most of these symptoms are short-term (temporary). They often lessen or go away when you stop using your computer or device. But symptoms may continue for a longer time.

The severity of symptoms may vary depending on:

  • How long you have been using the computer or digital device
  • Your underlying eye problems
  • Other factors that cause digital eye strain.

Symptoms may get worse if you don’t resolve the problem.

Using a computer or digital device for a long time can also lead to other symptoms. This includes neck and shoulder pain. This is often due to poor alignment and posture when using the computer or digital device. Some healthcare providers call these symptoms part of digital eye strain as well.

How is digital eye strain diagnosed?

Your eye care provider will make a diagnosis with a health history and complete eye exam. They will assess if any health problems, medicines, or environmental factors might be adding to your symptoms.

Your eye care provider may test the sharpness of your vision and how well your eyes focus and work together. For a more detailed exam your provider may want to dilate (enlarge) your pupils. Then they will use a device (ophthalmoscope) to look at the back of your eye. In some cases, you may need to get follow-up blood tests for healthcare problems that might be helping to cause your digital eye strain.

How is digital eye strain treated?

Treatment includes creating a better work environment.

  • Rest your eyes at least 15 minutes after each 2 hours of computer or digital device use.
  • Every 20 minutes, look into the distance at least 20 feet away from the computer or digital device. Do this for at least 20 seconds.
  • Enlarge the text on your computer screen or digital device.
  • Reduce glare from the light sources in your environment.
  • Think about using a screen glare filter.
  • Place your screen so that the center of it is about 4 to 5 inches below eye level (about 15 to 20 degrees from the horizontal).
  • Place your screen about 20 to 28 inches from your eye.( About arm’s length.)
  • Remember to blink often.
  • Fix your chair height so your feet can rest comfortably on the floor. Don’t slump over the computer screen.

Making these changes may help eliminate digital eye strain in many people.

Your eye care provider will also need to treat any hidden health problems that may be adding to your digital eye strain. For instance, you might need a new pair of glasses. If you have an underlying dry eye problem, your eye care provider might advise the following:

  • Using lubricating drops
  • Treating allergies, if you have them
  • Creating a more humid work environment
  • Drinking more fluids (staying hydrated)
  • Taking a prescription medicine to increase tear production

What can I do to prevent digital eye strain?

Create a better work environment to help prevent digital eye strain. If you use glasses or corrective lenses, see your eye care provider at least once a year or as advised for a checkup. Also see your healthcare provider regularly. This can help prevent and treat health problems that can help cause digital eye strain.

Key points about digital eye strain

  • Digital eye strain is a group of related eye and vision problems caused by extended computer or digital device use.
  • Symptoms include eye discomfort and fatigue, dry eye, blurry vision, and headaches.
  • Uncorrected vision problems are a major cause.
  • Sometimes hidden health problems help to cause it.
  • Having a better computer work environment may help improve symptoms.
  • Resting your eyes regularly is one of the best ways to prevent and treat digital eye strain.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your healthcare provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your healthcare provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your healthcare provider if you have questions.
Posted on

Muscles, Nerves, and Blood Vessels in the Human Eye

By David Terfera, Shereen Jegtvig

Muscles enable you to move your eyes. Ocular nerves allow you to interpret what you see and blood vessels keep your eyes oxygenated. Six muscles, collectively called the extraocular muscles, move the eyeball. A seventh muscle moves the eyelid and is also found in the orbit.

The muscles of the human eye

The following muscles help your eyes move around.

image0.jpg

  2. Education
  3. Science
  4. Anatomy
  5. Muscles, Nerves, and Blood Vessels in the Human Eye

Muscles, Nerves, and Blood Vessels in the Human Eye

By David Terfera, Shereen Jegtvig

Muscles enable you to move your eyes. Ocular nerves allow you to interpret what you see and blood vessels keep your eyes oxygenated. Six muscles, collectively called the extraocular muscles, move the eyeball. A seventh muscle moves the eyelid and is also found in the orbit.

The muscles of the human eye

The following muscles help your eyes move around.

image0.jpg

  • Levator palpebrae superioris: Originates on the sphenoid bone above the optic canal. It inserts into the superior tarsis and skin of the eyelid. It’s innervated by the oculomotor nerve and elevates the superior eyelid.

  • Superior oblique: Originates on the sphenoid bone and inserts into the sclera deep to the superior rectus muscle. It’s innervated by the trochlear nerve and abducts, depresses, and medially rotates the eyeball.

  • Inferior oblique: Originates on the anterior part of the orbital floor and inserts onto the sclera deep to the lateral rectus muscle. It’s innervated by the oculomotor nerve and abducts, elevates, and laterally rotates the eyeball.

  • Superior rectus: Originates on the common tendinous ring and inserts into the sclera behind the corneoscleral junction. It’s innervated by the oculomotor nerve, and it elevates, adducts, and medially rotates the eyeball.

  • Inferior rectus: Originates on the common tendinous ring and inserts into the sclera behind the corneoscleral junction. It’s innervated by the oculomotor nerve and depresses, adducts, and laterally rotates the eyeball.

  • Medial rectus: Originates on the common tendinous ring and inserts into the sclera behind the corneoscleral junction, this muscle is innervated by the oculomotor nerve and adducts the eyeball.

  • Lateral rectus: Originates on the common tendinous ring and inserts into the sclera behind the corneoscleral junction. It’s innervated by the abducent nerve and abducts the eyeball.

The nerves of the eye

The eyes are served by the following cranial nerves and their branches:

image1.jpg

  • Optic nerve (CN II): Sensory nerve that transmits impulses from the retina to the brain

    • Oculomotor nerve (CN III), trochlear nerve (CN IV), and abducent nerve (CN VI): Enter the orbital space through the superior orbital fissure to innervate the extraocular muscles.

    • Ophthalmic nerve (part of the trigeminal nerve, CN V): This nerve has three branches:

      • The lacrimal nerve runs to the lacrimal gland and gives off branches to the conjunctiva and skin of the superior eyelid.

      • The frontal nerve enters through the superior orbital fissure and provides sensory innervation to the superior eyelid, scalp, and forehead.

      • The nasociliary nerve is the sensory nerve to the eyeball. It also has branches that serve the orbit and other parts of the face. One of its branches, the infratrochlear nerve, supplies the eyelids, conjunctiva, and lacrimal sac.

    • Ciliary ganglion: This group of postsynaptic parasympathetic nerve cell bodies is associated with the oculomotor nerve and ophthalmic nerve (CN V1). Presynaptic parasympathetic fibers from the oculomotor nerve synapse on the cell bodies of postsynaptic parasympathetic neurons in the ciliary ganglion.

      Short ciliary nerves emerge from the ciliary ganglion and enter the eye. The short ciliary nerves contain postsynaptic parasympathetic fibers from the ciliary ganglion, afferent fibers of the nasociliary nerve, and postsynaptic sympathetic fibers from the internal carotid plexus. Postsynaptic parasympathetic fibers innervate the ciliary muscle and sphincter pupillae muscle. Afferent fibers convey sensory impulses from the iris and cornea. Postsynaptic sympathetic fibers innervate the dilator pupillae muscle.

      The long ciliary nerves contain afferent and postsynaptic sympathetic fibers from the nasociliary nerve. Long ciliary nerves bypass the ciliary ganglion and run to the iris, cornea, and dilator pupillae muscle.

    The blood vessels

    Blood flow to the orbit (and beyond) comes from branches of the internal carotid artery, chiefly via the ophthalmic artery and its branches:

    • Ophthalmic artery: Branches from the internal carotid artery and passes through the optic canal into the orbital cavity

    • Central artery of the retina: Runs from the ophthalmic artery to the eyeball alongside the optic nerve; it branches at the optic disc and supplies the retina

    • Supraorbital artery: Starts at the ophthalmic artery and exits the orbit at the supraorbital notch to supply the forehead and scalp

    • Supratrochlear artery: Runs from the ophthalmic artery to the forehead and scalp

    • Lacrimal artery: Runs from the ophthalmic artery along the lateral rectus muscle to supply the lacrimal gland, conjunctiva, and the eyelids

    • Dorsal nasal artery: Branches from the ophthalmic artery and runs along the nose to supply it with blood

    • Short posterior ciliary arteries: Branch from the ophthalmic artery and pierce the sclera at the edge of the optic nerve; they supply the choroid and the rods and cones of the retina

    • Long posterior ciliary arteries: Branch from the ophthalmic artery and pierce the sclera to supply the ciliary body and iris

    • Posterior ethmoidal artery: Leaves the ophthalmic artery to supply blood to ethmoidal cells

    • Anterior ethmoidal artery: Runs from the ophthalmic artery to supply ethmoidal cells, frontal sinus, nasal cavity, and skin over the nose

    • Anterior ciliary artery: Runs from the muscular branches of the ophthalmic artery through the sclera near the rectus muscles and forms an arterial network in the iris and ciliary body

    • Infraorbital artery: Runs from the maxillary artery along the infraorbital groove and out to the face

    Blood is returned from the orbits via the superior and inferior ophthalmic veins, which pass through the superior orbital fissure into the cavernous sinus. The central vein of the retina may join an ophthalmic vein or enter the cavernous sinus directly. Vorticose veins drain the vascular layer of the eyeball, and the scleral venous sinus encircles the anterior chamber of the eyeball.