What Causes Dimness of Vision?

When looking at a vibrant field of flowers, if all is well with your eyes the colors may pop. But what if you begin to notice that in some parts of the visual field the colors are somewhat muted or things are starting to look gray? You know you haven't experienced any kind of eye injury but feel as if something must be amiss.

Dimness of vision can be a symptom connected to a variety of eye conditions. This article takes a closer look at what may be causing dim vision in these situations.

Potential Causes of Dimness of Vision - Illustration by Laura Porter

Verywell / Laura Porter

Causes of Dim Vision

While dim vision may seem to come out of the blue, there is always a reason it develops. The key is to find the condition that is causing the dimming of vision in your case. Learn about some of the conditions that can be at the root of such vision issues.

Optic Neuritis

With optic neuritis, it may appear as if someone has secretly dimmed the lights on you. At the root of this condition is inflammation of the nerves responsible for transmitting visual information to your brain from your retina (the light-sensing layer at the back of the eye).

Each nerve fiber transmits a part of the information from the retina. Depending on how many nerve fibers are affected, vision may be very poor or seem almost normal.

Other symptoms of optic neuritis to be aware of include:

  • Muted color vision where shades may look faded or dull
  • Blurry vision affecting at least one eye, particularly after getting out of a hot tub or exercising vigorously
  • Pain behind your eye, particularly when moving them

For optic neuritis, a diagnosis may be based on medical history and not being able to factor in another cause for vision loss. Also, damage to nerves from optic neuritis may be shown on magnetic resonance imaging (MRI), helping to confirm this diagnosis.

A case of optic neuritis may sometimes resolve on its own. In other instances, if vision loss is severe, an intravenous steroid, methylprednisolone, may be given to help hasten visual recovery.

Amblyopia

Those with amblyopia have one strong eye and the other with dim or blurred vision. This condition, which develops in infancy or childhood, is also called "lazy eye." If this is not treated, over time it will get worse.

Amblyopia can occur when there is a big difference in how the two eyes see. One eye may be initially weaker due to a large refractive error (nearsightedness or farsightedness), cataract (clouding of the lens), droopy eyelid, or even a corneal scar.

If a child learns to rely on the stronger eye, vision in the weaker one doesn't develop properly and make the needed connections to the brain. Treatment is needed to ensure that this does not happen.

To help diagnose amblyopia, an ophthalmologist can check a child to see if there is a big discrepancy between the two eyes. They can also cover one of the child's eyes and see how they react—whether they still track objects or try to pull off the eye covering.

Treatment hinges around getting the child to use the weaker eye. This can be done with patching, drops, or eyeglasses that blur the stronger eye.

Macular Degeneration

Cases of macular degeneration can come in one of two forms—dry or wet. The dry form tends to progress very slowly with the development of a few small deposits known as drusen. These can lead to dimming vision.

While there aren't many drusen early on, these may grow in size and number over time and get in the way. As a result, things may start to look dimmer when trying to read.

Because macular degeneration may have few (if any) symptoms early on, annual eye exams are key to detecting this. During the exam, the ophthalmologist will check the retina and macula for any signs of deterioration.

If dry macular degeneration is found, a specific formula of nutritional supplements (AREDS supplements) may help slow progression. Other treatments may be used for cases of wet macular degeneration, in which abnormal blood vessels have begun leaking. These include:

  • Anti-VEGF (vascular endothelial growth factor) injections to help keep new blood vessels from forming
  • Photodynamic therapy (PDT) in which a light-sensitive drug is injected into the arm and then a laser is used to get rid of abnormal blood vessels

Retinal Detachment

One of the first signs of a retinal detachment may be a shadow dimming part of your vision that does not go away. With a retinal detachment, the light-sensitive layer becomes detached from the back of the eye. These are the cells that we rely on for detecting light and sending signals about an image to the brain.

Other symptoms that can sometimes be associated here include flashes of light or spots or specks that float across your field. Or, you may experience a sudden loss of your peripheral vision, as though a curtain has been drawn there.

To determine if you have a retinal detachment, the practitioner will ask about your symptoms and examine your retina with a device known as an ophthalmoscope that illuminates and magnifies the area.

If a retinal detachment is found, immediate surgical treatment is needed to reattach it. This can be done with the aid of gas bubbles to press the retina back in place and the use of a laser or freezing probe to seal any retinal tears.

Glaucoma

In cases where glaucoma seriously affects your eyes, one of the important warning signs can be suddenly hazy vision. This can portend trouble and should not be ignored.

Glaucoma, a disease in which the optic nerve slowly dies over time, notoriously doesn't usually cause any symptoms at the outset. But if this isn't caught early on, there can be permanent vision loss.

Other imminent warning signs requiring immediate attention include rainbows or halos around lights, vision loss that occurs suddenly in one eye, or unusual black spots or flashes of light. If you have any of these signs, it's critical to seek immediate attention from an ophthalmologist.

While severe glaucoma will have symptoms, this is not so for early cases. Because of this, it's essential to get regular eye exams to check for it. The ophthalmologist will dilate the eye to examine the retina, check ocular pressure, look for changes in the ocular nerve, and check for any visual field loss.

If treatment is needed, this may include medication to lower eye pressure, laser treatment to improve fluid drainage, or surgery to improve fluid outflow. Keep in mind that while this may help reduce further damage, it will not improve any visual loss that has already occurred.

Cataract

With a cataract, the eye's lens becomes cloudy and harder to see through. Things can suddenly appear dim, blurry, or less colorful. Other signs that you may have a cataract may include seeing double, trouble seeing at night, and light sensitivity.

A cataract can be diagnosed by simply testing visual acuity and dilating the eye to see inside. If a cataract is found and is severe enough, the cloudy lens can be removed with surgery. The lens is replaced with a clear intraocular lens.

Brain Tumor

A brain tumor can also impact vision depending on its location. Symptoms may include noticing suddenly blurry or dim vision in some cases. If this involves swelling of the optic nerve, other vision changes may include areas of vision loss, double vision, or blindness.

If your vision is dim or even just somewhat off, it's important to get to the bottom of what's going on and rule this out. Other sensory changes may include differences in smell, hearing, or sensation.

Additional signs that a tumor may be pressing on the brain include muscle twitching, loss of consciousness either partially or completely, having a seizure, memory loss, and headaches. These should be immediately evaluated.

To help diagnose a brain tumor, a doctor will perform a neurological evaluation. They will also rely on imaging tests to determine where the tumor is and whether it can be safely biopsied. They will also look for signs of tumors in your eyes. Any tumor that is found will be staged to determine if this has migrated elsewhere in the body.

Treatment usually involves surgically removing any tumor, if possible, although continued monitoring is done in some cases. Also, sometimes chemotherapy and radiation may be used to help shrink the tumor.

Diagnosis and Treating Dimness of Vision

As you can see, it's important not to simply shrug off cases of dim vision. This should be thoroughly checked out by a qualified eye practitioner, preferably an ophthalmologist (a medical or osteopathic doctor specializing in eye diseases and surgery). For an issue such as dim vision, all eye practitioners are not the same.

While an optician may be great at dispensing glasses and an optometrist ideal for performing general eye exams and correcting refractive errors, an ophthalmologist is needed for this kind of eye condition often affecting the retina. Also, only an ophthalmologist will be able to perform surgery on your eyes if it is necessary.

Sudden dimness of vision in one or both eyes needs to be taken very seriously. This can also be a sign that someone is experiencing a stroke and needs immediate attention. Other signs that can point to a stroke include:

  • A severe headache suddenly coming on out of the blue
  • Numbness or weakness suddenly appearing
  • Dizziness all of a sudden
  • Difficulty speaking or understanding others suddenly
  • Sudden paralysis of a part of the body, such as a part of the face, leg, or arm

If you have any of these signs along with your dim vision, it's an emergency and it's important to get to a hospital immediately. Don't hesitate to call 911.

Summary

Dimness of vision may be noted due to muted color vision or gray areas. This is a symptom of a variety of conditions, including amblyopia, optic neuritis, retinal detachment, macular degeneration, glaucoma, cataracts, or brain tumor.

If you note dimness of vision, see an ophthalmologist to have the problem diagnosed and treated. Depending on the condition, the treatment may include medication, therapeutic procedures, or surgery.

A Word From Verywell

Having suddenly dim vision can be very disconcerting, but it can be a good thing because this can serve as a sign that something needs your attention. This dim vision does not have to stay that way. The good news is that in many cases this can be easily diagnosed and treated, especially if this is early in a disease process.

Frequently Asked Questions

  • What causes darkening of vision?

    This can be due to a variety of factors from issues involving inflammation of the optic nerve with a condition like optic neuritis to problems with the retina such as detachment. Each case needs to be individually evaluated and addressed.

  • Can you get dimness of vision in one eye?

    Absolutely. A condition such as a cataract, for example, may only be an issue in one eye. Even conditions like macular degeneration and glaucoma may only affect one eye. Whether it's one eye or both, it's important to get this checked out.

  • What is a veil in the eye?

    This can show where vision is decreased and may also be described as a dark curtain. Commonly, this can be associated with a retinal detachment. But there may be other explanations.

  • What is the dimness of vision or partial loss of sight without detectable disease of the eye called?

    This is called amblyopia, otherwise known as lazy eye. With this, one eye is weaker and the pathway to the brain does not develop properly unless this is recognized and treated early on.

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15 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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