What to do if you have a sudden loss of vision


By John L. Henahan,
Special to The Citizen

A sudden loss of vision in one or both eyes is one of the scariest experiences a person can have, says Dr. John Henahan of Spectrum Eyecare in Peachtree City.
When you experience a sudden change in vision, it’s important to remain calm and ask yourself some simple questions to help your doctor uncover a cause, says Dr. Henahan.

Here is what to pay attention to:
• How long ago did the problem first arise? Hours? Days? Months?
• Has my vision changed in one eye or both eyes? Cover one eye at a time and look around to decide.
• How long did the vision loss last? A few seconds, several minutes or is it persisting?
• Is the vision loss a blur, a dark spot, or bright shimmering effect?
• Does the area of vision loss stay in the same area of your vision or does it move around independently of your eye movements?
• Did it come on suddenly or has it been gradually worsening?
• Is the eye painful? Is it red? Are you more sensitive to light than normal?

All of these questions can help the nurses and doctor pinpoint the most likely cause of your vision loss, to perform a focused exam to confirm the cause and to quickly begin treatments to help save your vision.

Causes of sudden blurred vision that doesn’t threaten your vision

A common visual disturbance that does not indicate a threat to the vision is a migraine headache.


Migraines can begin at any age. Often they have no visual symptoms, but in a classic migraine, the headache is preceded by a visual disturbance, often called an “aura.” The classic aura is a bright, shimmering “C” shaped blur that starts in the center of vision (in BOTH eyes). It gradually moves from the center of vision off to the side where it eventually dissipates (usually after about 20 minutes). When followed by a headache, it is known as a classic migraine. When no headache occurs, it is called a visual or ophthalmic migraine.

Dry Eye

Dry eye can cause sudden blurred vision. Typically, the complaint is that the vision goes out of focus when reading or on the computer. Closing the eyes or blinking several times seems to resolve the issue. The blur usually lasts less than one minute and is described as having a foggy quality.

Vision-threatening causes of sudden blurred loss

There are many possible causes of sudden sight-threatening vision loss.The most common causes are described below:
Retinal Detachment

A sudden onset of dark floating spots in front of one eye, especially when accompanied by flashes of bright light and blurred vision can indicate a sight threatening emergency called retinal detachment. When caught early, this serious condition is highly treatable and vision is likely to be saved. If treatment is delayed then irreversible vision loss can occur in the affected eye.

Retinal bleeding (from macular degeneration or diabetes)

The retina is a highly organized, amazingly precise structure. When that organization is disrupted, the vision becomes distorted, blurry or both. In diabetes and wet macular degeneration, blood leaks out of blood vessels and into the retina causing it to swell. This bleeding disrupts the organization of the retina and causes vision loss that is perceived as a dark blurred spot or distorted vision. Generally, even if the blood dissipates the retina never regains totally normal function because the precise organization is permanently affected.

If you are diabetic, it is essential to control your blood sugar and to have a complete dilated retinal eye exam at least once per year. Early treatment is key to retaining good vision if retinal bleeding develops in your retina. Any sudden change in vision in one eye is considered a serious issue that warrants an eye check within several days.
In macular degeneration (AMD), the problem is usually a deterioration of the retina that can sometimes result in bleeding in the retina. If this bleeding occurs you can experience a sudden loss of central vision that feels like a dark spot in the center of vision. New treatments have been developed for this “wet AMD” that have greatly improved outcomes, but still usually result in some residual vision loss.

Glaucoma attack

Normally, glaucoma is notable for the absence of symptoms and the decades it takes to cause blindness. A less common form of glaucoma called sudden angle closure glaucoma can cause permanent loss of vision in just a few days. In sudden angle closure, the eye pressure skyrockets to more than three times its normal amount. As the pressure in the eye builds, it destroys the optic nerve. The symptoms include an extremely painful red eye with blurred vision. The pain can be so intense that vomiting often occurs.

If you suspect that you are having sudden angle closure glaucoma, it is imperative that you seek care immediately. Various eye drops and oral medications can quickly stop the attack, allowing the eye pressure to return to its normal level. A simple laser treatment can prevent future attacks after the initial crisis has subsided.

The iris is the colored part of the eye that allows the pupil to expand and contract depending upon how bright the environment is. A large number of medical problems can result in inflammation developing in the iris. It can occur in one or both eyes. When iritis develops, the eye feels sore with a deep ache, light sensitivity and blurred vision. If untreated, iritis can lead to permanent damage to the eye, as well as causing cataracts and a type of glaucoma that is very difficult to control. Treatment usually consists of drops. A complete physical and blood tests may be needed to determine the underlying cause of the iritis. Treatment of any systemic health problems can reduce the chance of recurrence.


If you experience a sudden loss of vision that persists for more than 30 minutes, contact your eye doctor for an appointment.
Dr. John Henahan is a fellowship-trained doctor of optometry practicing and living right here in Peachtree City with his wife and two sons.  You may call his office at 770-487-0667 or visit him on the web at www.speceye.com.