Patient Information

Eye leaflets

Colchester Eye Centre
Colchester Primary Care Centre
Tel: 07780 005 814
Monday to Friday, 9am–5pm


Floaters and flashing lights

Symptoms of floaters and flashing lights are relatively common complaints among our patients.

Floaters are commonly described by patients as black dots, irregular semi-transparent lines, circles, cobweb or veil-Iike shadows that are seen to move around across the field of vision with the eye movements. They become more noticeable when looking at white surfaces and in bright light. Most often, floaters are experienced in otherwise healthy individuals, more commonly among short-sighted people.

Floaters are thick parts or strands of the vitreous gel in the back chamber of the eye (see diagram). They move freely inside the vitreous and thus can drift over and interfere with the light path and their shadow on the retina is seen as floaters.

diagram of the eye showing a floater in the path of light in the eye

This diagram of the structure of the eye shows that a floater in the vitreous cavity is visible because it can interrupt the light path, casting a shadow on the retina.

Flashing lights are transient, bright white or coloured flickers that are perceptible when suddenly moving the head – more frequently in the dark – usually at the outer edge of vision. They are the result of mechanical stimulation to the retina by the vitreous.

The symptoms of floaters and flashing lights most commonly result from a condition called posterior vitreous detachment (PVD). This is a common condition, occurring in more than 60% of people over the age of 40 and its incidence increases with age.

In the majority of cases, vitreous detachment causes no harm and, therefore, does not need any treatment and the symptoms become less noticeable with time. However, sometimes as the vitreous separates, it can tug off part of the retina causing a retinal tear. The torn retina could lead to fluid seeping underneath and lifting the rest of the retina off. This is called retinal detachment and surgical intervention will be needed to treat it. If detected early, retinal tears can be treated with a laser, which seals off the torn edges preventing the development of retinal detachment.

If you have floaters or flashing lights that developed suddenly or if you develop recurrence of these symptoms, especially if they are associated with reduced vision or loss of a part of your visual field, you need to be seen promptly by an eye specialist.

For advice out of hours

Weekdays 5pm–7pm and weekends and bank holidays, 11am–4pm, please telephone 01206 286 882, or contact your GP, or go to a walk-in centre or the nearest accident and emergency department.



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