Flashing lights, floaters, or a gray shadow in your vision. The sudden onset of flashing lights, a noticeable increase in the amount of floaters, a shadow in your peripheral vision, or a gray curtain moving across your field of vision could be signs of a detachment of the retina — the nerve layer in the back of the eye that sends images to the brain. Nearsightedness, eye diseases such as glaucoma, and physical injury to the eye are among the causes of retinal detachment. Unless treated quickly, usually with surgery, retinal detachment can lead to blindness.
Any loss of vision, particularly if sudden or in one eye. Sudden vision loss could signal a number of eye diseases and conditions. One is macular degeneration, also known as age-related macular degeneration or AMD, which is a leading cause of vision loss in people 65 and older in the United States. Vision loss caused by AMD can be gradual, but in some cases, it can be sudden — when blood vessels in the eye leak fluid or blood under the retina, which is made up of nerve cells that allow you to see. Another cause of sudden vision loss could be a type of glaucoma, which leads to a rapid build-up of fluid pressure in the eye that damages the optic nerve.
Eye pain. Most eye diseases are painless, but some conditions or injuries can result in eye pain, says Richard Shugarman, MD, a spokesperson for the American Academy of Ophthalmology and an ophthalmologist in West Palm Beach, Fla. Eye pain can be caused by glaucoma, dry eye, an eye injury, a scratched cornea, or even cancer of the eye.
Eye injury. Any significant injury to the eye should be evaluated by a doctor, particularly if there is redness or pain that lasts for more than 15 to 20 minutes.
Persistent discomfort in the eye. If you experience any discomfort in your eye after doing an activity in which a small particle could have entered your eye, such as hammering or working under a car, don’t ignore it. Have your eyes checked out by a doctor to make sure that you don’t have a foreign particle in the eye, which can cause an infection.
Red eye. “Having two red eyes is probably not as serious as one red eye,” says Dr. Shurgarman. When both eyes are red at the same time, it could be a sign of a cold or conjunctivitis (pink eye) — minor infections that are self-healing. But one red eye can be an indicator of a deeper inflammation, such as scleritis or uveitis. Scleritis is the inflammation of the tough, outer protective barrier around the eye, and uveitis is the inflammation and swelling of the middle coating of the eyeball.
Eye discomfort if you are a contact lens wearer. While most people who use contact lenses don’t experience problems when they follow the rules of proper contact lens care and use, serious infections can occasionally occur. If you wear contact lenses, never ignore eye pain, redness, or discomfort — see an eye doctor right away.