The sudden onset of floaters and flashing lights is usually associated with posterior vitreous detachment, particularly when they occur in a patient’s 50’s or 60’s. The vitreous is the gelatinous structure that fills the back of the eye, having served its role primarily in the development of the eye. As the gel breaks down it liquifies and finally collapses, pulling itself free from the retina. Only the posterior aspect of the gel separates from the retina, hence the term posterior vitreous detachment (PVD). Once floating freely, opacities in the vitreous and along its posterior face (the posterior hyaloid or vitreous cortex) are more apparent in the vision. The arcs of flashing lights in the peripheral vision are caused by gentle traction at the leading edge of the vitreous separation from the retina.
Most of the time, PVD formation is a benign process that does not threaten the vision. However, sometimes it can pull on the retina, causing a retinal tear. If not treated in time, a retinal tear can lead to a retinal detachment. The detached retina causes a shadow to occur in the vision which can spread throughout the vision if not treated. Because there is no way to tell if new floaters or flashing lights represent a simple PVD, or a tear or detachment, it is recommended to seek care promptly. Please call our office if you are concerned you are having new floaters or flashing lights.
A retinal tear can lead to a retinal detachment. Floaters are often the first warning sign of a problem.
Another cause of sudden onset, painless floaters, is bleeding in the vitreous. Blood in the eye can form long, stringy opacities as the red blood cells may be trapped in one of the vitreous gel’s many cisterns. The red blood cells can also be dispersed like a drop of ink in water, resulting in thousands of little specks and a diffuse haze. In patients with diabetic retinopathy, bleeding in the eye may represent the development of proliferative diabetic retinopathy, a condition where abnormal blood vessels grow along the surface of the retina and the vitreous gel. In patients with risk factors for atherosclerosis (high blood pressure, diabetes, high cholesterol, smoking, family history, sleep apnea, age, etc), bleeding may occur from a blockage of a retinal vein. Bleeding in the eye may also be associated with trauma, diabetes, hypertension, violent valsalva (bearing down), and congenital vascular malformations. Finally, a PVD with or without a tear or detachment can cause bleeding in the eye.
A more gradual onset of floaters and/or shimmering flashing lights throughout the central vision can be a symptom of inflammation in the eye. Inflammation in the eye may be caused by an autoimmune condition, either isolated to the eye or in association with systemic disease. An infection is another common cause of inflammation in the eye. The severity can range from a mild viral infection or represent a serious life threatening bacterial illness. In older patients, the development of floaters can occasionally be caused by cancer.