When a posterior vitreous detachment (PVD) occurs, if the vitreous is abnormally attached to the retina, the retina may be pulled and torn. The tear is usually U-shaped and may also be described as a horseshoe tear.
Retinal tears with symptoms such as flashes and floaters almost always require treatment. Depending on features of the tear and the view into your eye when you’re examined, this may require laser treatment, freezing treatment (cryo) or both.
How Are Retinal Tears Treated?
There are two types of treatment for retinal tears and both work by causing a burn that heals as a scar. This sticks the retina to the underlying retinal pigment epithelium (RPE) and the treatment is called retinopexy. This can be done with either a laser or cryo and the latter is often chosen if there is a problem with the view into the eye or if there is already a small retinal detachment present.
Laser is a very high-energy bright light that, when directed and focussed on to a retina, is absorbed by the RPE. By applying several of these spots all the way around the retinal tear, the scar that forms prevents any fluid that goes through the tear from slipping under the retina and stripping it off. This is similar to spot-welding.
The laser retinopexy (sticking down of the retina) can be done either with the patient sitting up at a special slit lamp that has been fitted with a laser or with the patient lying down and the laser fitted to a head-mounted device worn by the surgeon called an indirect ophthalmoscope. The reason for choosing one over the other is usually to do with which gives a better view all the way around the tear. It can take 10-14 days for laser retinopexy to reach full strength.
After treatment there may be a mild ache for the rest of the day and patients can often see a sparkle or glow for weeks corresponding to where the laser was applied.
The main risk of laser treatment is a burn to the fovea, which could permanently damage central vision. This is avoided by following a number of safety procedures and is extremely rare.
Cryo-retinopexy sets up a burn with scarring, but cannot be done without local anaesthetic; it is performed under local anaesthetic as a day case.
The freezing is applied using a probe on the surface of the white of the eye (sclera) and can cause the eye to ache and feel gritty for a few days. It also takes 10-14 days for cryo-retinopexy to reach full strength.
Cryo machines use the expansion of either carbon dioxide or nitrous oxide to reach very low temperatures
Exceptions To Retinal Tears Requiring Treatment
The two main exceptions to retinal tears needing treatment are:
- when a chunk of retina is pulled completely off the retina, leaving a roundish hole and with no vitreous pulling on the attached retina. This is known as an operculated tear and has a very low chance of developing into a retinal detachment.
- when a retinal tear is found during a routine retinal examination and there have definitely been no symptoms of flashes or floaters.
After discussion with their retinal specialist some patients choose to have both of these types of tear treated anyway.