The vitreous gel inside the eye changes in consistency as we get older and most people note grey floaters in their vision often from their 20’s. This occurs because solid filaments of gel move around in a more liquid matrix and, in bright lighting conditions, cast shadows back on the retina. These floaters are rarely concerning, and the brain is very adept at filtering this ‘junk information’ so that we don’t see them all the time.

As we get older, the gel changes further in consistency and starts to separate away from the retina in a process known as posterior vitreous detachment (PVD). Patients frequently report a grey circle in their vision, or ‘frog spawn’ or a ‘spiders web’ appearing. This is sometimes accompanied by flashes of light which represents traction from the gel on the retina. This can be alarming for patients and if it happens acutely, you should probably have this looked at.

If there is a further acute onset of black floaters, this may be a retinal tear. This occurs when the gel is too firmly adherent to the peripheral retina and pulls on it causing a tear to form. This can lead to a retinal detachment and should be seen urgently for treatment with either laser or cryotherapy to weld the retina shut to prevent detachment.

The retina is the photosensitive film at the back of the eye that turns light into electrical signals that are carried to the brain to allow us to see. The retina can become detached from the wall of the eye. There are a number of different causes.

A ‘rhegmatogenous’ retinal detachment is the commonest form, when a tear in the retina, caused because of posterior vitreous detachment, allows fluid from the jelly cavity underneath the retina. Patients may note flashes of light and black floaters initially when the tear is forming. This can then proceed to a gradually increasing shadow coming across the vision from the periphery. This is a sight threatening emergency.

If the retinal detachment involves the centre of the vision (the macula) then the quality of the vision will usually be permanently damaged. It is important therefore important to try to operate on a retinal detachment before the macular becomes detached. If the macula is off, surgery will still be performed and much vision recovered but it less imperative that it is performed on an emergency basis.

There are a number of surgical approaches and the technique used will depend on both surgical preference, age of patient, and the exact type of retinal detachment.

A macular hole is a vitreo-retinal condition where a hole appears at the middle of the patient’s vision at the fovea in the centre of the retina.

It is usually caused by abnormal adhesions between the jelly of the eye (vitreous) and the retina. As we get older, the vitreous frequently separates away from the retina in a process known as posterior vitreous detachment (PVD). In some cases however the vitreous is firmly stuck to the retina and traction from the gel pulls a hole. Patients frequently complain of difficulty with reading or seeing faces and there is often distortion at the centre of the vision.

This hole can be closed with surgery. Your surgeon will perform a vitrectomy (removal of the vitreous); a thin membrane on the surface of the retina is then peeled off (ILM peel); and the eye is then filled with gas.

You may be asked to “posture” after surgery: this involves looking or lying face down so that the gas bubble is in contact with the hole. This may be for a number of days. Not all surgeons advocate this however.

The vision will take some time to recover and is unlikely to be quite as good as it used to be. The distortion is usually much improved and there is more central detail than preoperatively.

An epiretinal membrane (also known as macular pucker, or cellophane maculopathy) is a layer of scar tissue that forms over the centre of the retina at the macula. This acts like all scar tissue does – which means that it contracts. This pulls the underlying retina into folds causing thickening and distortion of the retinal architecture. This in turn can cause distortion of a patient’s vision and blur.

Treatment is most commonly with surgery. Your surgeon will perform a vitrectomy – to remove the vitreous gel of the eye. The epiretinal membrane is then stained with a special dye. It can then be peeled off the surface of the retina.

The vision takes some time to recover; it can sometimes get transiently worse post operatively, as removal of the membrane causes inflammation and thickening of the retina (rather as the skin becomes red and swollen after removal of a sticky plaster). Over several months, however, the retinal architecture improves and the quality of vision with it.