I found this on another site: {quote]Common Causes

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

* Presbyopia -- difficulty focusing on objects that are close. Common in the elderly.
* 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.

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(medicineonline.com)