The key retinal defect in the above type of retinal detachment is a retinal tear. The thin retinal tissue is prone to tear when it is pulled upon by vitreous gel, the substance that fills the vitreous cavity. As we age, this gel normally liquefies and separates from the retina in a process called vitreous detachment. As the gel separates, two symptoms are often experienced: 

First, collagen particles suspended in the vitreous cavity can produce a sensation of floaters; patients often describe “cobwebs” or “bugs” in their vision.

Second, any pulling on the retina stimulates the light sensors in this nerve tissue; this often results in flashes that are described as white lightning streaks. When the vitreous gel pulls on the retina, the most common result is a gradual release of the gel and resolution of symptoms. The flashes often disappear completely, while floaters tend to linger.

In some cases, the traction of the gel on the retina occurs near a blood vessel; this can result in shearing of the blood vessels and bleeding into the vitreous cavity. The patient experiences a different type of floaters caused by blood cells floating in the liquefied vitreous gel; sometimes this is severe enough to cause temporary blindness. Finally, as a precursor to retinal detachment, vitreous traction on the retina can result in tearing of the retinal tissue. Floaters can be caused by pigment cells released from the space under the retina.

At the first signs of floaters or flashes, individuals are advised to consult with their retinal specialist immediately. It is hoped that the tear(s) can be identified and sealed before fluid (liquefied gel) starts to seep under the retina and cause retinal detachment. Left alone, fluid will generally continue to accumulate under the retina and peel the retina off the eyewall. At the initial stages, patients often notice a shadow in their peripheral (side) vision. As time progresses, the shadow gets closer and closer to the central vision. Eventually, the center of vision (the macula) usually will detach if left untreated. It is very important to try to repair a retinal detachment before the central vision is involved, as macular involvement often results in permanent visual loss or symptoms. Once the macula detaches, it is still important to reattach it to attempt to restore as much vision as possible.

The reason that retinal detachment is so critical is that it is a potentially blinding disease. The retina depends on two blood supplies to function properly and allow one to see. The first blood supply is within the retina. The second is on the back wall of the eye. When a retina detaches, it is separated from this second blood supply and the retinal nerve tissue is starved of oxygen and nutrition. The longer the retina is detached, the more nerve cells ultimately die. After a retinal detachment is repaired and the blood supply is restored, cells often recover; however, cells that have died cannot be replaced and this is what is responsible for potential permanent visual loss.