Retinal Tears and Detachments
Diagram from Medscape.com depicting a single horseshoe retinal tear with a localized superotemporal retinal detachment in a phakic patient.
A retinal detachment is a separation of the retina from its attachments to the underlying tissue within the eye. Most retinal detachments are a result of a retinal break, hole, or tear. These retinal breaks may occur when the vitreous gel pulls loose or separates from its attachment to the retina, usually in the peripheral parts of the retina. The vitreous is a clear gel that fills two-thirds of the inside of the eye and occupies the space in front of the retina. As the vitreous gel pulls loose, it will sometimes exert traction on the retina, and if the retina is weak, the retina will tear. Most retinal breaks are not a result of injury. Retinal tears are sometimes accompanied by bleeding if a retinal blood vessel is included in the tear. It is common for people to develop separation of the vitreous from the retina as they get older (Poterior Vitreous Detachment or PVD). However, only a small percentage of these vitreous separations result in retinal tears.
Once the retina has torn, liquid from the vitreous gel can then pass through the tear and accumulate behind the retina. The buildup of fluid behind the retina is what separates (detaches) the retina from the back of the eye. As more of the liquid vitreous collects behind the retina, the extent of the retinal detachment can progress and involve the entire retina, leading to a total retinal detachment. A retinal detachment almost always affects only one eye at a time.
These are conditions that can be seen in an Optos screening during a normal eye exam.