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changes in vision
Changes in vision can take many forms and have many causes. A person may lose vision completely, develop cloudy vision, or have poor vision only under certain conditions.
What is going on in the body?
Vision changes may include blurry vision, double vision, cloudy vision and other changes. Vision changes can be caused by anything from normal ageing to life-threatening conditions.
What are the signs and symptoms of the condition?
Kinds of vision changes include:
The doctor will need to know the kind of vision change and:
- decreased sharpness of vision, or being unable to focus on objects up close or far away, or both
- double vision, which means a person can see two of everything
- reduced peripheral, or side, vision
- total loss of vision, or blindness
- cloudy vision, which feels as though the person is looking through a dirty windshield
- "blind spots," or areas of vision where the person can only see blackness
The doctor may also ask about other symptoms, such as headache, nausea, vomiting, weakness, or muscle pains.
- when the vision change started
- whether it came on quickly or slowly
- whether one or both eyes are affected
- whether near vision, far vision, or both, is affected
- whether there is any pain associated with the vision change
- what medications the person takes
- what other medical conditions the person has
- whether there is any family history of vision changes
What are the causes and risks of the condition?
The possible causes of vision changes include:
Other causes of vision changes are possible. Sometimes, no cause can be found.
- refractive errors, such as being nearsighted, farsighted or having presbyopia. Presbyopia means difficulty seeing things up close, due to age-related changes in the eye. This condition affects almost all people over age 50. It's the reason older people often need bifocals or reading glasses.
- infections of the eye, such as conjunctivitis or keratitis
- cataracts, a common condition caused by changes in the lens of the eye
- glaucoma, a condition caused by increased pressure within the eye
- damage or inflammation of the nerves of the eye
- damage to the vision areas of the brain, due to a stroke or brain tumour
- damage to the retina, the part of the eye that is similar to the film inside a camera. The retina can be damaged in diabetes, macular degeneration, or retinal detachment.
- trauma, or injury, to the eye
- strabismus, or "lazy eye," in which the eyes don't line up properly
- temporal arteritis, an inflammation of the arteries that supply blood to the eye
- vitamin A deficiency
- medications, such as the heart medication digitalis, or the antibiotic ethambutol
What can be done to prevent the condition?
Prevention is depends on the cause. Early detection and treatment of glaucoma can often prevent vision loss. Control of diabetes can help prevent vision changes. Frequent hand washing and not touching the eyes with the hands helps prevent conjunctivitis. Many cases of vision changes cannot be prevented.
How is the condition diagnosed?
A history and physical examination, including an examination of the eye, are done first. An eye examination may involve having the person read an eye chart. The eye may be examined with special instruments, and the pressure inside the eye may be measured. Eye drops can be put into the eye to make the pupils get bigger. This lets the doctor see the inside of the eye better. These steps may be all that's needed to make the diagnosis. In other cases, further testing is needed.
The tests that are ordered vary depending on the suspected cause. A cranial CT scan may be done if a brain tumour or stroke is suspected. A blood test can help diagnose temporal arteritis or diabetes.
What are the long-term effects of the condition?
Long-term effects depend on the cause. Presbyopia causes permanent difficulty seeing near objects. But reading glasses or bifocals are the only treatment needed and there are no other long-term effects. A brain tumour can cause death. Glaucoma, macular degeneration, and diabetes can result in permanent blindness.
What are the risks to others?
Vision changes are not contagious and pose no risks to others. If the cause is an eye infection, such as conjunctivitis or keratitis, the infection may be contagious.
What are the treatments for the condition?
Treatment is directed at the cause. Medications are often used to control diabetes or glaucoma. Retinal detachment, cataracts, some types of glaucoma, and brain tumours can be treated with surgery. Eye infections may need to be treated with antibiotics. Nearsightedness is usually treated with glasses or contact lenses.
What are the side effects of the treatments?
Side effects depend on the treatments used. All medications have possible side effects. For example, medications used to control diabetes may cause liver damage or allergic reactions. Surgery carries a risk of bleeding, infection, or loss of vision. Contact lenses may irritate the eyes or result in eye infections.
What happens after treatment for the condition?
Treatment varies according to the cause of the vision change. After a person gets glasses for farsightedness, no further treatment is needed. People with diabetes or glaucoma usually need close monitoring and treatment for life. Macular degeneration usually causes vision to get worse over time.
How is the condition monitored?
A person should tell the doctor about any vision changes or responses to treatments. Repeat eye examinations are advised for many causes of vision changes. Children with a lazy eye may need close monitoring along with surgery, special glasses, or a patch put over one eye.
Author: Adam Brochert, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request