The retina is the light-sensitive layer of tissue that lines the inside of the eye and sends visual messages through the optic nerve to the brain. The vitreous inside the eye (see image) can pull on the retina and cause a tear. Retinal tears occur in about 2 percent of eyes at the time of a posterior vitreous detachment. Once there is a tear, fluid can travel from inside the eye to under the retina. The risk of retinal detachment in an eye with a fresh retinal tear is about 70 percent. Treatment can reduce the risk of a tear progressing to a retinal detachment to about one percent. Ten percent of eyes with a retinal tear develop subsequent retinal tears, most within the first 2 months of onset of the symptoms.
Symptoms include a sudden or gradual increase in either the number of floaters, which are little “cobwebs” or specks that float about in your field of vision, and/or light flashes in the eye. At least half the time when the retina tears, a blood vessel in the retina is broken. When that occurs, blood is released into the vitreous which looks like hundreds of tiny pepper spots. You can see a little blood next to the retinal tear in the accompanying image. The spots might look black or red. Retinal tears occur in the far periphery of the retina. Unless there is also a retinal detachment, the change in vision from a retinal tear is not noticeable. If someone sees a shadow and loss of side vision, that means the retinal tear has progressed to a retinal detachment.
A retinal tear can be treated with laser surgery or cryotherapy. Both accomplish the same goal:creating an adhesion around the tear to prevent a retinal detachment. The accompanying image shows fresh laser spots surrounding a retinal tear. Both treatments are safe with a very small risk of complications. Both laser and cryotherapy do not immediately create an adhesion. The adhesion is fairly good at one week and very good at four weeks. So it is important to ease into jarring activity following treatment for a retinal tear. Anything that creates excessive movement of the eye can be dangerous until the adhesion is formed. Reading, because of the back and forth movement of the eyes, is usually discouraged for a time following treatment of a retinal tear. About 10 percent of people who have had a retinal tear develop a subsequent retinal tear. Therefore if new and different symptoms occur following treatment it is important to notify your physician.
Small asymptomatic retinal holes are not uncommon and usually do not need to be treated. Some surveys suggest that retinal holes are common and may exist in up to 8 percent of all eyes. The reason that retinal holes rarely cause retinal detachments is that they are not under traction. There are several forces that keep your retina attached. There is a suction force exerted by the retinal pigment epithelium. In addition, the retinal cells interdigitate with the underlying retinal pigment epithelial cells holding the retina in place like Velcro. To create a retinal detachment, a sufficient tractional force has to pull the retina out of position to allow fluid to traverse a retinal hole and enter the subretinal space and cause a retinal detachment. The absence of traction around a retinal hole seems to prevent retinal holes from progressing to retinal detachments.