Retinal Tears & Detachments
What is a Retinal Tear?
A retinal tear is exactly what it sounds like – a tear in the fabric of nerve tissue that lines the inside of the eye, called the retina. Retinal tears typically occur at the thin edge of the retina. Tears are seen in two forms – a triangular horseshoe tear and a circular tear that often has a small divot of retina floating over the circle (operculated hole).
The vitreous jelly inside the eye sticks more firmly at the edge of the retina and “tugs” while it is being peeled off. This tugging is the cause of flashes, and if the tugging is strong enough a retinal tear may develop. If a retinal tear occurs in the location of a retinal blood vessel, the blood from such a torn vessel leads to a showering of new floaters (vitreous hemorrhage).
How Are Retinal Tears Treated?
All tears that are new and all tears, new or old, that are associated with sudden new symptoms of flashes and/or floaters require prompt treatment. The object of treatment for a retinal tear is to create a firm adhesion, called a retinopexy, between the retina and the wall of the eye so that the liquefied vitreous cannot pass through the tear and then dissect underneath the retina and cause a retinal detachment. The usual way such an adhesion is formed is by creating a circle of small scars around the tear with a laser. Sometimes if the view of the retina is so poor, i.e. from a dense cataract or from blood in the vitreous cavity, the adhesion is created by using a metal probe cooled to -20°C. This freezing metal probe, called a cryoprobe, is placed against the wall of the eye underneath the tear, where the local inflammation caused by the freezing creates the desired adhesion. A similar process using a transcleral diode laser can also achieve the same result.
What Is a Retinal Detachment?
A retinal detachment is a separation of the nerve tissue of the retina from the wall of the eye. When this separation occurs, the cells of the nerve tissue are isolated from their supplies of nourishment, will deteriorate, and eventually die. It is therefore imperative that a retinal detachment be repaired in order to prevent permanent loss of vision in the affected eye. The most common type of retinal detachment is called a rhegmatogenous retinal detachment. Rhegmatogenous retinal detachments occur when fluid from the vitreous cavity flows through a retinal tear and dissects underneath the retina, thus raising it up off the wall of the eye. Similar to the posterior vitreous, the retina is only firmly attached to the wall of the eye at the optic nerve, and at the far peripheral edge of the retina. The rest of the retina is attached to the wall of the eye in a fashion similar to a suction cup. Once a small amount of fluid gets underneath the retina, the “seal” is broken and the dissecting fluid can spread rapidly.
The initial symptoms of a retinal detachment are the same as a retinal tear or a posterior vitreous detachment, i.e. flashes and floaters; however, as the detachment progresses, a dark, opaque moon-shaped shadow or curtain will appear from one side of your vision. This curtain, which can sometimes be seen to billow like a sail in the wind, is actually the detached retina tissue floating in the vitreous cavity.
Retinal detachments can be divided into two separate levels of severity, depending upon whether the very important back portion of the retina, called the macula, is affected by the detachment. Since retinal detachments tend to start in the periphery as “macula on” retinal detachments, and only later progress to “macula off” retinal detachments, the prognosis for the return of normal vision after the repair of a “macula on” detachment is better. In addition, “macula off” detachments which are less than a week old tend to have a better visual prognosis than older “macula off” retinal detachments. Since retinal detachments tend to start in the periphery as “macula on” retinal detachments, and only later progress to “macula off” retinal detachments, it is very important to seek out an ophthalmologist immediately upon the earliest detection of the suspicious symptoms outlined above. Fortunately, with modern surgical techniques, over 90% of all retinal detachments can be successfully repaired. Current methods of retinal detachment repair can be done on an outpatient surgery basis and sometimes even in the office.
Besides rhegmatogenous retinal detachment, the other types or retinal detachments – tractional and serous behave very differently. Tractional retinal detachments generally occur when scar tissue from inside the eye pulls off the retina. This most commonly happens in eyes with advanced diabetic retinopathy. Serous retinal detachments occur when fluid accumulates underneath the retina like a blistering of fluid. This can occur in a variety of diseases including inflammatory diseases, tumors or other primary eye diseases.
How are retinal detachments repaired?
Most retinal detachments require urgent surgical repair. The object of any retinal detachment repair is to get rid of the fluid underneath the retina and allow the retina to lay “flat” upon the concave contour of the wall of the eye. There are several methods of achieving this goal, each of which will be discussed in the sections below. The great majority of retinal detachments are of the rhegmatogenous type, and these sections will primarily discuss repair of this type of detachment.
There are three ways to repair a rhegmatogenous retinal detachment: