What is Retinal Detachment?
The retina is a thin, light-sensitive tissue that covers the inside back portion of the eye. In most cases retinal detachment is caused by the presence of one or more small holes or tears in the retina.
When a retinal tear is present, watery fluid from the vitreous space may pass through the hole and flow between the retina and the back wall of the eye. This separates the retina from the back of the eye and causes it to detach. The detached portion of the retina will not work properly, and there will be a blur or blind spot in the vision.
Types of retinal detachment
Rhegmatogenous retinal detachment - a break, tear or hole develops in the retina, allowing liquid to pass from the vitreous space into the subretinal space between the sensory retina and the retinal pigment epithelium (the pigmented cell layer just outside the neurosensory retina).
Secondary retinal detachment - also known as exudative retinal detachment or serous retinal detachment. It is caused by inflammation, vascular abnormalities or injury which cause fluid to build up under the retina (there is no hole, break or tear).
Tractional retinal detachment - an injury, inflammation or neovascularization causes the fibrovascular tissue to pull the sensory retina from the retinal pigment epithelium.
What are the signs and symptoms of a detached retina?
Photopsia - the patient experiences sudden flashes of light which are very brief and in the outside of center part of their vision (peripheral vision). The flashes more commonly occur when the eye moves.
An enormous increase in the number of floaters. Floaters are bits of debris in the eye which make us see things floating in front of us, usually like little strings of transparent bubbles or rods that follow our field of vision as our eyes turn. Often it may be a ring of hairs or floaters on the temporal side of the central vision
The eye feels somewhat heavy
A shadow starts to appear in the peripheral vision. It gradually spreads towards the center of the person's field of vision
A sensation that a transparent curtain is coming down over the field of vision
Straight lines start to appear curved
There are several methods of treating a detached retina, each of which depends on finding and closing the breaks that have formed in the retina. All three of the procedures follow the same three general principles:
Find all retinal breaks
Seal all retinal breaks
Relieve present (and future) vitreoretinal traction
Cryopexy and laser photocoagulation
Cryotherapy (freezing) or laser photocoagulation are occasionally used alone to wall off a small area of retinal detachment so that the detachment does not spread.
Scleral buckle surgery
Scleral buckle surgery is an established treatment in which the eye surgeon sews one or more silicone bands (bands, tyres) to the sclera (the white outer coat of the eyeball). The bands push the wall of the eye inward against the retinal hole, closing the break or reducing fluid flow through it and reducing the effect of vitreous traction thereby allowing the retina to re-attach. Cryotherapy (freezing) is applied around retinal breaks prior to placing the buckle. Often subretinal fluid is drained as part of the buckling procedure. The buckle remains in situ.
The most common side effect of a scleral operation is myopic shift. That is, the operated eye will be more short sighted after the operation. Radial scleral buckle is indicated for U-shaped tears or Fishmouth tears, and posterior breaks. Circumferential scleral buckle is indicated for multiple breaks, anterior breaks and wide breaks. Encircling buckles are indicated for breaks covering more than 2 quadrants of retinal area, lattice degeneration located on more than 2 quadrant of retinal area, undetectable breaks, and proliferative vitreous retinopathy.
This operation is generally performed in the doctor's office under local anesthesia. It is another method of repairing a retinal detachment in which a gas bubble (SF6 or C3F8gas) is injected into the eye after which laser or freezing treatment is applied to the retinal hole. The patient's head is then positioned so that the bubble rests against the retinal hole.
Patients may have to keep their heads tilted for several days to keep the gas bubble in contact with the retinal hole. The surface tension of the gas/water interface seals the hole in the retina, and allows the retinal pigment epithelium to pump the subretinal space dry and "suck the retina back into place". This strict positioning requirement makes the treatment of the retinal holes and detachments that occurs in the lower part of the eyeball impractical. This procedure is usually combined with cryopexy or laser photocoagulation.
Pneumatic retinopexy has significantly lower success rates compared to scleral buckle surgery and vitrectomy. Some initially successful cases will fail during the weeks and months after surgery. In some of the failed cases, an area of the retina which was healthy and attached prior to the initial pneumatic retinopexy repair procedure develops new tears and/or becomes detached.
Vitrectomy is an increasingly used treatment for retinal detachment. It involves the removal of the vitreous gel and is usually combined with filling the eye with either a gas bubble (SF6 or C3F8 gas) or silicone oil. An advantage of using gas in this operation is that there is no myopic shift after the operation and gas is absorbed within a few weeks. Silicon oil (PDMS), if filled needs to be removed after a period of 2–8 months depending on surgeon’s preference.
Silicone oil is more commonly used in cases associated with proliferative vitreo-retinopathy (PVR). A disadvantage is that a vitrectomy always leads to more rapid progression of a cataract in the operated eye. In many places vitrectomy is the most commonly performed operation for the treatment of retinal detachment.