Detached Retina: Causes, Signs, and Symptoms
What is a Retinal Detachment (Torn Retina)?
Retinal detachment is a serious condition that can lead to severe visual impairment or even total blindness in the affected eye. The retina normally lies smoothly and firmly against the inside back wall of the eyeball and functions much like the film in the back of a camera. Millions of light-sensitive retinal cells receive optical images, instantly "develop" them, and send them on to the brain to be seen. If any part of the retina is lifted or pulled from its normal position, it is considered detached, and will cause some vision loss. The detachment will almost always progress, and vision loss will increase, until it is treated. Therefore, any new detachment is always considered an emergency. Retinal detachment can occur at any age, but it is more common in midlife and later. It affects men more than women, and Caucasians more than Blacks. It is more likely to occur in people who are extremely nearsighted. Heredity may also play a part, since it tends to run in families.
Detached Retina Causes
Any tiny tears or holes in the retina can allow fluid to seep under the retina, separating it from the back wall of the eye. The tiny tears themselves are usually caused by aging changes of some of the tissues within the eye. Most of the eye's interior is filled with vitreous, a gel-like substance that helps maintain its round shape. The vitreous contains millions of fine fibers that are normally attached to the retinal surface. As we age, the vitreous slowly shrinks away from the retina and may at some point be pulled free (this is called a vitreous detachment). Once in a while, this pulling results in one or more tears or tiny holes in the retina. Then, the fluid from the vitreous compartment of the eye can leak through the hole(s) and get under the retina.
A detached retina may also be the result of a hard blow or injury to the eye, though this is rather rare.
Detached Retina Symptoms
Because the retina is such a sensitive part of the visual system, anything that disturbs it will cause visual symptoms. When it tears, you are likely to have a sudden appearance of detached retina floaters -- a shower of "cobwebs" in your field of vision-- which may be accompanied by "flashes," a sensation of seeing a flashing bright light. Though it is normal to have a few floaters, and everyone has them, a sudden increase in their number and size is a warning that small amounts of blood and debris have suddenly appeared in the vitreous. The flashes are sensations from the retina as it is pulled or torn, or is rubbed by the loosened vitreous. If a tear breaks a larger retinal blood vessel, the blood spilling into the vitreous can cause a massive increase in floaters or even total loss of vision in that eye. The floaters will usually decrease in a few weeks or months and vision will improve, as long as the retina does not detach.
What are Additional Signs of a Retinal Detachment?
Most retinal detachments do not cause problems and are not especially dangerous. However, if fluid starts to leak through them, the retina will start to peel (like wallpaper) and the detachment process begins. At first, you may have no symptoms, especially if the detachment is off to the side. Later, a "curtain" of darkness will start moving in and block out vision from one direction (the position depends on the location of the detachment). When the peeling process reaches the central zone of the retina (the macula), vision will suddenly and dramatically blur. As time goes on (which could be hours, days, or weeks), the curtain will continue to darken more and more of your vision, until you are left only able to see bright light.
Retina Detachment Examination and Testing
A complete eye examination will be done after your pupils have been dilated (enlarged) with eye drops. The back of the eye will be examined with a special ophthalmoscope (worn on the doctor's head like a miner's light) and with a slit lamp (clinical microscope). Sometimes a gonioscope (a special type of contact lens with built-in mirrors) is placed on the eye so the retina can be closely visualized. The ophthalmoscope shines a very bright light into your eye. The light will be uncomfortable, but it is absolutely necessary for a careful and accurate evaluation. Every retinal tear and hole must be found. A drawing will be made to identify their positions and the extent of the detachment. This drawing will later serve as a "map" during surgery for locating the precise areas needing repair.