What is a retinal detachment?
The retina is essentially a thin sheet of light-sensitive nerve tissue that lines the back wall of the eye, much like wallpaper lines a wall of a room. If the retina tears, fluid can seep behind the retina through the opening caused by the tear. The gradual accumulation of fluid results in further separation of the retina from the eye wall, much like wallpaper peeling off a house wall. This is termed a retinal detachment. Contrary to widespread belief, retinal detachments don’t only occur in boxers and those who have experienced trauma; in fact, most retinal detachments occur through no fault of the patient. Retinal detachment surgery can reverse the detrimental effects of this condition.
Retinal detachment can affect any age group, male or female. Across the population, they occur in approximately 1 out of every 7000 people. There is a higher incidence with increasing nearsightedness; these eyes are longer and the retina tends to be stretched and thinned with a higher tendency to tear. Individuals with a condition called lattice degeneration are about 10 times as likely to develop a retinal detachment as this predisposes the retina to tearing. Certain inflammatory conditions and infections are associated with a higher incidence of retinal detachment. Retinal detachments are particularly common with certain viral infections of the retina. Trauma is a definite cause in a certain percentage of retinal detachments. In certain cases, no definite cause can be identified.
What are the symptoms of retinal detachment?
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.
How do you treat a retinal detachment?
When a retinal detachment is suspected, your retinal specialist will perform a detailed examination of the retina. The purpose is to identify the extent of the retinal detachment, find any retinal tear(s), and plan surgical repair. He or she will also be looking for any complicating conditions such as lattice degeneration. The examination process almost always involves pressing gently on the surface of the eye while looking in with a lens, a technique called scleral depression. This allows for a complete and accurate evaluation of the entire retina. Treatment of retinal detachment (regardless of technique) depends upon three factors: finding the retinal tear(s), sealing the retinal tear(s), and supporting the retinal tear(s).
A surgical approach will be formulated based on many variables including: number and location of tears, size of retinal detachment, degree of nearsightedness, presence of lattice degeneration, presence of vitreous hemorrhage, presence of a natural lens or cataract surgery, and age/health of the patient, among others.