Many foods and beverages -- including coffee, tea and chocolate --contain caffeine. Although caffeine will not likely cause serious health complications, its use may cause symptoms such as increased heart rate, shaky hands and anxiety. Blurred vision does not typically occur with caffeine use, but caffeine could increase the risk for certain eye conditions that may cause periodic blurring. Understanding the connection between caffeine and your eyes will help you determine if you should limit your caffeine intake.
The tears on the surface of your eye provide comfort and protection for the surrounding tissues. If you do not have enough tears you may experience dry eye problems, which include irritation, redness and episodes of blurry vision. In a 2004 study at the University of Wisconsin Medical School, researchers found that caffeine use increased the risk of dry eye. Not everyone with dry eye experiences vision changes, but, in this way, caffeine could play a role in causing blurry vision.
More commonly, blurry vision stems from a natural change in the eye that will require you to update your eyeglass prescription. Other causes for vision changes include eye conditions such as cataracts or macular degeneration. An eye infection, eye injury or foreign body in the eye may also cause vision changes. Diabetics also have an increased risk for vision changes associated with high blood sugar levels that damage the blood vessels in the eyes.
Other Eye Effects
Caffeine does not play a direct role in vision changes, but caffeine consumption may have other effects on the eyes. Glaucoma, a slow, progressive disease that destroys vision, requires good control of eye pressure to help slow down the disease process. Consuming large quantities of caffeine in a short period of time may cause an increase in eye pressure, reports the Glaucoma Research Foundation. A small spike in pressure may not cause harmful damage, but if you regularly consume large amounts of caffeine, this could lead to further damage to your eyes.
You may also experience twitchy eyelids if you consume caffeinated products. This does not cause damage to your eyes or vision, and once the caffeine leaves your system, any twitching related to caffeine should stop.
If you experience changes in your vision, you need to contact your eye doctor right away. You may have a condition that requires prompt treatment to avoid permanently damaging your eyes or visual acuity.