symptoms of eye disorders
eye disorders
Eye Flashes and Floaters
Eye flashes result when something besides light from the environment stimulates the retina, which is the light-sensing structure at the back of the eye. This stimulation causes the retina to send a signal to the brain. The brain may interpret the signal as a simple, sudden flash of light that can look like lightning, spots, or stars (photopsia). Photopsias can occur when the eyes are rubbed. Eye floaters are seen when an object in the eyeball casts a shadow on the retina, which is the light-sensing structure at the back of the eye. This is often interpreted as an apparent object or objects floating in the external field of vision. A person may think they are seeing a swarm of flies, gnats, or specks but then realize they are not actually present. The most common cause of eye flashes and floaters is Shrinking of the jellylike substance that fills the eyeball (vitreous humor) In early adulthood people may notice occasional floating strands in the vision of one or both eyes relating to contraction of the vitreous humor. These types of floaters (called contraction or idiopathic vitreous floaters) rarely indicate anything harmful. Between about age 50 to 75 years, however, the vitreous humor continues to shrink and tugs on the retina from time to time. These tugs may stimulate the retina, giving the illusion of light, seen as flashes. Over time, the vitreous humor usually pulls completely away from the retina (vitreous detachment) as a normal part of aging. Less common but more serious causes include Detachment of the Retina None Tear in the retina Bleeding in the vitreous humor Inflammation of the vitreous humor Sometimes Migraines cause vision symptoms. These vision symptoms may be white, jagged flashing lines that appear first in the middle of the field of vision and then spread across the entire field of vision (not single objects like floaters). They typically then resolve over about 20 minutes, disappearing first from the peripheral field of vision and last from the center of the field of vision. People may not have a headache with them. These symptoms are called ocular or visual migraine. People can also have similar symptoms or lose vision in part of an eye for about 10 to 60 minutes, often before a migraine headache begins (called migraine aura). In these cases, symptoms are caused by a phenomenon in the brain, not in the retina. Flashes of light can also result from a blow to the back of the head ("seeing stars"), probably because of stimulation of the part of the brain where vision is interpreted. Tumors (for example, Overview of Lymphoma ) of the eye and vitritis (inflammation of the vitreous humor) are rare causes of floaters. 