Understanding vitreomacular traction surgery

What is vitreomacular traction?
What causes vitreomacular traction?
How does vitreomacular traction affect your sight?
When should you have surgery for vitreomacular traction?

 

What is vitreomacular traction?

Vitreomacular traction is an uncommon condition in which shrinkage of the vitreous jelly within the eye pulls on the central macular area of retina. This causes central visual impairment, either in the form of a generalised blurring or distortion.

Rarely, the shrinkage of the vitreous jelly within the eye results in a partial separation, with some jelly remaining attached to the very central macular area of retina. The cause of this is unknown and it is only in the last few years with the advent of OCT retinal scanning that we have been able to recognise this appearance.

It is helpful to know a little about the eye and how it works in order to understand what effect vitreomacular traction has on the vision, and how it can be treated.

Anatomy of a normal eye

The wall of the eye is formed by three layers, the retina, the choroid and the sclera.

The retina is the light-sensitive nerve tissue that lines the inner wall of the eye. Rays of light enter the eye, passing through the cornea, pupil and lens before focusing on to the retina. The retina contains photoreceptors which convert these light rays into electrical impulses.

In the healthy eye these impulses are sent via the optic nerve to the brain where sight is interpreted as clear, bright, colourful images. The retina can be likened to photographic film in a camera.

The macula is a small area at the centre of the retina. It is very important as it is responsible for our central vision. It allows us to see fine detail for activities such as reading, recognising faces, watching television and driving. It also enables us to see colour.

The choroid is the underlying vascular (blood vessel) layer of the eye from which the retina receives oxygen and nutrients.

The vitreous is the clear jelly-like substance which fills the hollow space behind the lens. As we age this vitreous gel opacifies and shrinks away from the retina. This is very common, occurring in about seventy-five per cent of people over the age of sixty-five.

Separation of the vitreous gel from the retina is known as posterior vitreous detachment or “PVD”. It does not itself cause any permanent loss of vision although floaters may be troublesome.

Example of vision with floaters

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What causes vitreomacular traction?

The normal ageing process of the vitreous results in shrinkage of the gel and ultimately a separation from the retina. There are points on the retina where the vitreous jelly can be unusually adherent and one of these is in the very central macular area.

The retina is multi-layered and ongoing traction (“pull”) from the jelly can result in a swelling of the macular area as the retinal layers separate. The inner layers are pulled inwards towards the vitreous cavity whilst the outer layers remain adherent to the eye wall. The situation worsens as normal eye movements cause the jelly within the eye to rotate, this movement producing a relentless pull on the macula.

OCT image showing vitreomacular traction with “pull” and swelling of the macular area

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How does vitreomacular traction affect your sight?

Common symptoms of vitreomacular traction are;

  • the appearance of a blurred patch in the central vision;

  • distortion of straight lines, which appear broken or bent;

  • a loss of contrast sensitivity – “greying” of central vision;

  • loss of colour vision.

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When should you have surgery for vitreomacular traction?

The procedure to treat this condition involves removal of the vitreous jelly, and requires a vitrectomy operation.

The purpose of surgery is to separate the vitreous gel from the underlying macula, such that the retinal layers can return to a more normal position. As this happens, there is every chance that further visual loss will be avoided and in most cases a degree of visual improvement is possible.

Vitreomacular traction is potentially progressive. Early surgery offers the best chance of long-term visual success. Even when few symptoms are present, surgery may be considered to prevent further worsening.

We will help you decide if vitrectomy surgery for vitreomacular traction is appropriate for you.

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