Flashes & Floaters

Well it's been a while since my last post, but we'll return to the issue of retinal detachments here. Detachments generally occur from breaks in the retina, the neurosensory tissue that lines the back of our eye and is responsible for cpaturing the visual image. A retinal break occurs from a tractional, or pulling, force exerted upon the retina by the vitreous humor, the gelatinous substance that fills the back of our eye and lines our retina.

Certain individuals are at particular risk of developing retinal breaks - namely those who are nearsighted, have a family history of retinal detachments, a past history of head or eye trauma or eye surgery, and those with systemic medical disorders affecting the structural tissues that form the eye and vitreous humor. Retinal detachments are more common in men, and race, too, is a proven determinant. Asians and Indians have a higher frequency of retinal detachments, vice versa for those of African descent.

But detachments can occur in everyday normal sighted individuals as well, simply from having too many birthdays. As we age so does our vitreous humor. When we were not yet born, the vitreous was a dynamic biological structure filled with vessels that nourished and helped develop the eye. Yet, by the time we entered this world, the blood vessels had regressed and all that was left of the vitreous was a clear matrix consisting of strands of collagen (a structural protein) held together by sugar molecules. In a young eye, the vitreous fills the back and firmly adheres to the retina. As time passes, though, the sugar linkages begin to break down and liquefied pools of fluid begin to form within the vitreous, a phenomenon called vitreous syneresis. This is what gives us floaters, or the little particles of debris that float around in our eye. This process of liquefaction eventually reaches a critical state, just when that occurs varies but the incidence typically increases in the fifth and sixth decades of life, and the vitreous humor separates entirely from its posterior and peripheral connections to the retina. Called a vitreous separation or vitreous detachment, such an event is often accompanied by flashes and a sudden increase in floaters. In most cases, the process is benign and the flashes and floaters dissipate over time as the vitreous humor continues to liquefy, but in some a retinal tear may occur in areas of abnormal vitreoretinal traction. When a retinal break is present, liquefied vitreous can pass through the defect into the subretinal space resulting in elevation and detachment of the retina.

Well, just how common are retinal tears and detachments? Tears are found in up to 1/10th of the population but detachments occur less frequently, at an incidence of approximately one in every 10,000 individuals. From this we can gather that the majority of retinal breaks, fortunately, do not lead to retinal detachments. Still, because retinal detachments are significantly harder to treat than tears, it befits patients to have any potential tears properly assessed and treated before they might become more serious concerns. If a tear is found, it can be treated right away before it becomes a detachment. That is why anytime someone experiences flashes or floaters or loss of their visual field, even if it might just be a benign change of the vitreous humor, it's important you call you eye doctor and have a thorough dilated eye exam.