Imagine that your eye is like a camera and the retina is the film. The retina is a fine sheet of nerve tissue lining the inside of the eye. Rays of light enter the eye and are focused on the retina by the lens. The retina produces a picture, which is sent along the optic nerve for the brain to interpret.
Usually, the retina is attached to the inner surface of the eye. If there is a tear or hole in the retina, then fluid can get underneath it, which weakens the attachment so that the retina can fall off. When this happens the retina cannot compose a clear picture and your vision distorts blurs and dims. Ultimately all useful vision is usually lost from the eye, which may then become shrunken, inflamed, or painful.
The most common symptom is a ‘shadow’ or ‘curtain’ moving across the vision of one eye. You may also experience bright flashes of light and/or showers of dark spots called “floaters”.
If help is sought early and the torn retina is still attached, it may only be necessary to “spot weld” the retina with a laser or freezing treatment. If the retina is detached, it must be reattached before sealing it on. Sub-specialist “Vitreo-retinal” surgeons use one or more of three ways to repair a detached retina:
Pneumatic retinopexy involves injecting a special gas bubble into the eye that stabilises the retina in place whilst it is healing. With this procedure, you may well be required to position your head (and eye!) such that the gas provides maximal support to the retinal tear. The gas will normally resolve in 3-10 days and air travel is not possible during this time.
The scleral buckle procedure requires fluid to be drained from beneath the detached retina before a flexible piece of silicone sponge is sewn onto the outer eyewall to support the tear from outside.
Vitrectomy surgery removes the vitreous gel from the posterior chamber of the eye. It is traction from the vitreous that is the usual cause of retinal tears, and it may continue to pull on the retina stopping reattachment. The vitreous is replaced by a gas bubble (or silicone oil), with the former being gradually replaced by the body fluids.
Repairing a detached retina is not always successful. In some eyes, the retina may re-detach due to the development of new tears or scarring on the surface of the retina.
Peripheral vision (the ‘shadow’ or ‘curtain’) will recover if the retina is successfully flattened.
However, if the detachment involves the part of the retina, which is responsible for your central vision, this will not recover fully. Within reason, the earlier the retina is reattached, the better the anatomical and visual outcomes.