The natural history of a retinal detachment is blindness. “Natural history” of a disease is the same as the usual outcome. So, the usual outcome of a retinal detachment is complete blindness if eye surgery is not performed.
Retinal tears and holes cause a retinal detachment. A small amount of fluid goes through the tear and gets underneath the retina causing the detachment. With time the amount of fluid increases underneath the retina, and so, too, the size of the retinal detachment enlarges.
Because all tears and holes occur in the peripheral retina (the portion of the retina giving us peripheral, or side, vision), you always lose your side, or peripheral vision, first. As the detachment grows, the macula becomes detached and central vision will eventually be lost. The initial goal of retinal detachment surgery is to fix the detachment before the central eyesight is affected. By doing so, you minimize the risk of permanent loss of your central.
We usually try to operate within days.
When the macula (central portion of the retina responsible for reading, etc.) detaches, there can be permanent loss of eyesight despite successful surgery.
The retina is a laminated tissue. It has several layers. The rods and cones are underneath the top layer. Loss of vision from a detachment is due to the physical separation of the rods and cones (aka photoreceptors) from the layer beneath them.
There are several ways to fix a retinal detachment. These are outlined in the overview of retinal detachments. The goal of any retinal detachment surgery is to prevent blindness by reattaching the retina and, if possible, fix the eye before central vision is affected.
Chronic, or longstanding, retinal detachments are those unfortunate eyes that were never diagnosed or operated upon. In general, eye surgery doesn’t always work to restore sight in these cases. Permanent damage to the rods and cones occurs with time, and, despite success in reattaching the retina, vision does not return.
By chronic, I’d say conditions lasting months to years.
In extreme cases of retinal detachments that never get repaired, the eye can start to die and shrink. This condition, phthisis bulbi, occurs when the retina has not been attached for years (generally). While it doesn’t always occur, it can be extremely disfiguring and can be a psychological nightmare.
What Does This Mean? Because the outcome of a retinal detachment is so grim, surgery is almost always recommended. If the natural history is blindness, that is, the chance of going blind is 100%. Though there are risks of eye surgery (blindness), the chances are small. Thus, there really isn’t much to lose by operating.