Floaters may appear in your vision as spots of varying shapes. Often they are noticed when looking at a plain background, looking into the sky, or at a wall. Floaters are caused when the gel that fills the inner eye, the vitreous humor, develops clumps or strands. When light hits the clump, it creates a shadow on the retina, which is perceived as a floater in your vision; the spots may appear to be outside, but they are really inside your eye.
The young vitreous has the consistency of thick gelatin; this same vitreous gel, as the eye ages, starts to liquefy and becomes similar to water. Eventually, the gel will shrink and separate from the rest of the eye causing a posterior vitreous detachment (PVD). Eighty percent of patients above 60 years of age will have a posterior vitreous detachment. As the vitreous separates it can pull on the retina, causing flashes to appear as flashing lights or lightning streaks. As the gel pulls away from the retina, it may stimulate the retinal cells. The brain interprets this stimulation as a flash of light. These flashes can appear on and off for multiple weeks, and become more common as the eye ages. However, they can be due to other conditions such as a retinal tear or detachment.
As the vitreous separates, it may find a firm attachment to the surface of the retina and may pull on the retina, causing a retinal tear. People with symptomatic PVD have a 10- 15 % risk of having a retinal tear, and if there is bleeding in the eye there is a 70% chance of having a tear. If a tear occurs, the liquefied vitreous can enter the tear and cause a retinal detachment. For this reason, if you have any flashes or floaters in your vision, you should contact your eye doctor immediately to make sure you do not have any condition that requires treatment. If a retinal tear is caught early, laser treatment or a freezing treatment could prevent a retinal detachment. If a retinal detachment is found, an early diagnosis is better than ignoring its symptoms.
Your eye doctor may dilate your pupil with eye drops to perform a full examination. The exam is painless, and your doctor will examine all the areas of your eye including the retina and vitreous gel. If your eyes have been dilated, you will require a ride home after your appointment.
Some patients experience flashes of light that appear as jagged lines in both eyes at once, which last from minutes to hours; these flashes can start in the middle and zigzag around until they vanish in the periphery, and are usually the result of an ocular migraine and may not be related to retinal pulling.