Changes in vision, blurriness, blind spots, halos around lights, or dimness of vision should always be evaluated by a medical professional. Such changes may represent an eye disease, aging, eye injury, or a condition like diabetes that affects many organs in your body.

Whatever the cause, vision changes should never be ignored. They can get worse and significantly impact the quality of your life. Professional help is always necessary. As you determine which professional to see, the following descriptions may help:

• Opticians dispense glasses and do not diagnose eye problems.
• Optometrists perform eye exams and may diagnose eye problems. They prescribe glasses and contact lenses. In some states, they treat diseases that affect the eyes.
• Ophthalmologists are physicians who diagnose and treat diseases that affect the eyes. These doctors may also provide routine vision care services, such as prescribing glasses and contact lenses.
• Sometimes an eye problem is part of a general health problem. In these situations, your primary care provider should also be involved.

Vision changes and problems can be caused by many different conditions:

• Presbyopia -- difficulty focusing on objects that are close. Often becomes noticeable in your early to mid 40s.
• Cataracts -- cloudiness over the eye's lens, causing poor nighttime vision, halos around lights, and sensitivity to glare. Daytime vision is eventually affected. Common in the elderly.
• Glaucoma -- increased pressure in the eye, causing poor night vision, blind spots, and loss of vision to either side. A major cause of blindness. Glaucoma can happen gradually or suddenly -- if sudden, it's a medical emergency.
• Diabetic retinopathy -- this complication of diabetes can lead to bleeding into the retina. Another common cause of blindness.
• Macular degeneration -- loss of central vision, blurred vision (especially while reading), distorted vision (like seeing wavy lines), and colors appearing faded. The most common cause of blindness in people over age 60.
• Eye infection, inflammation, or injury.
• Floaters -- tiny particles drifting across the eye. Although often brief and harmless, they may be a sign of retinal detachment.
• Retinal detachment -- symptoms include floaters, flashes of light across your visual field, or a sensation of a shade or curtain hanging on one side of your visual field.
• Optic neuritis -- inflammation of the optic nerve from infection or multiple sclerosis. You may have pain when you move your eye or touch it through the eyelid.
• Stroke or TIA.
• Brain tumor.
• Bleeding into the eye.
• Temporal arteritis -- inflammation of an artery in the brain that supplies blood to the optic nerve.
• Migraine headaches -- spots of light, halos, or zigzag patterns are common symptoms prior to the start of the headache. An ophthalmic migraine is when you have only visual symptoms without a headache.

Other potential causes of vision problems include fatigue, overexposure to the outdoors (temporary and reversible blurring of vision), and many medications.

Medications that can affect vision include antihistamines, anticholinergics, digitalis derivatives (temporary), some high blood pressure pills (guanethidine, reserpine, and thiazide diuretics), indomethacin, phenothiazines (like Compazine for nausea, Thorazine and Stelazine for schizophrenia), medications for malaria, ethambutol (for tuberculosis), and many others.

Call 911 if:

• You experience partial or complete blindness in one or both eyes, even if it is only temporary.
• You experience double vision, even if it is temporary.
• You have a sensation of a shade being pulled over your eyes or a curtain being drawn from the side.
• Blind spots, halos around lights, or areas of distorted vision appear suddenly.
• You have eye pain, especially if also red. A red, painful eye is a medical emergency.

Call your provider if you have:

• Trouble seeing objects to either side
• Difficulty seeing at night or when reading
• Gradual loss of the sharpness of your vision
• Difficulty distinguishing colors
• Blurred vision when trying to view objects near or far
• Diabetes or family history of diabetes
• Eye itching or discharge
• Vision changes that seem related to medication (DO NOT stop or change a medication without talking to your doctor)

Your provider will check vision, eye movements, pupils, the back of your eye (called the retina), and eye pressure when needed. An overall medical evaluation will be done if necessary.

Your provider will ask questions about your vision problems, such as:

• When did this begin? Did it occur suddenly or gradually?
• How often does it occur? How long does it last?
• When does it occur? Evening? Morning?
• Is the problem in one eye or both eyes?
• Is your vision blurred or is there double vision?
• Do you have blind spots?
• Are there areas that look black and missing?
• Is side (peripheral) vision missing?
• Are halos (circles of light) seen around shiny objects or lights?
• Do you see flashing lights or zigzag lines?
• Do you have sensitivity to light?
• Do stationary objects seem to be moving?
• Are colors missing? Is it difficult to differentiate colors?
• Is there pain?
• Are your eyes crossed? Does one or both of your eyes "drift"?
• Have you had an injury, infection, allergy symptoms, added stress or anxiety, feelings of depression, fatigue, or headache in the last few weeks to months? Have you been exposed to pollens, wind, sunlight, or chemicals in this time frame? Have you used any new soaps, lotions, or cosmetics?
• Is your vision better after you rest?
• Is it better with corrective lenses?
• Are there other symptoms present like redness, swelling, headache, pain, itching, discharge/drainage, a sense that something is in the eye, increased or decreased tearing, etc.?
• What medications do you take?

• Do you have diabetes or is there a family history of diabetes?

• Slit-lamp examination
• Refraction test
• Tonometry

Treatments depend on the cause. Surgery will be recommended for some conditions (such as cataracts). Diabetics must control their blood-sugar level.

Regular eye checkups from an ophthalmologist or optometrist are important. They should be done once a year if you are over age 65. Your doctor will recommend earlier and more frequent exams if you have diabetes or you are already showing early signs of eye problems from diabetes, high blood pressure, or other causes.

The pressure in your eyes will be measured at some visits to test for glaucoma. Periodically, your eyes will be dilated to examine the retina for any signs of problems from aging, high blood pressure, or diabetes.

These important steps can prevent eye and vision problems:

• Wear sunglasses to protect your eyes.
• Don't smoke.
• Limit how much alcohol you drink.
• Keep your blood pressure and cholesterol under control.
• Keep your blood sugars under control if you have diabetes.
• Eat foods rich in antioxidants, like green leafy vegetables.

US Preventive Services Task Force. Screening for glaucoma: Recommendation statement. Ann Fam Med. 2005; 3(2): 171-172.

Spierer A. Presbyopia among normal individuals. Graefes Arch Clin Exp Ophthalmol. 2003; 241(2): 101-105.