Flashes of light, especially at the edge of vision. A sudden shower of new floaters, particularly if it looks like soot or a swarm. A shadow or curtain coming across part of your vision from one side. Any of these means a retinal tear or detachment until proven otherwise, and all three warrant being seen the same day.
The vitreous gel that fills the eye shrinks with age and separates from the retina. Usually this is harmless. But where the vitreous is abnormally adherent, it can pull a tear in the retina as it separates. The pull stimulates the retina mechanically, which the brain interprets as light — that is the flash.
When a tear happens, retinal pigment cells and blood escape into the vitreous. Those cells cast shadows on the retina, and you perceive them as new floaters. A sudden burst of them, especially with flashes, is a classic presentation of an acute tear.
Once fluid passes through a tear and lifts the retina off the back wall of the eye, the detached portion stops working. You perceive this as a shadow that does not move with your eye, often described as a curtain. Detachment involving the macula — the centre of vision — has a substantially worse visual prognosis, and the difference is often measured in hours to a couple of days.
A tear without detachment can often be sealed with laser retinopexy or cryotherapy in clinic, which is quick and prevents progression. A detachment requires surgery — pneumatic retinopexy, scleral buckle, or vitrectomy depending on the configuration. The earlier it is done, the better the outcome.
Do not wait to see whether it settles. Do not assume it is a migraine because you have had migraines. Do not drive yourself if the vision is affected in a way that worries you. Ring, describe the symptoms, and come in.
This article is general information about eye conditions and does not replace an examination. If you have symptoms, book an assessment.
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