A curtain or shadow across vision is a red-flag symptom and may indicate retinal detachment or stroke-like problems.
Retinal causes of a curtain
When the retina pulls away from the back of the eye, part of the visual field can disappear. The shadow is usually painless but progresses over hours or days.
- Retinal detachment often follows new floaters and flashing lights
- Bleeding inside the eye can also cause dark patches
- Tears or holes in the retina may create a creeping shadow
- Short-sighted people and those after eye surgery are at higher risk
Other serious possibilities
Sudden visual field loss can also result from blocked blood vessels or brain events. These situations require emergency care.
- Stroke affecting the visual pathways may cause side vision loss
- Eye strokes occlusions reduce blood flow to the retina
- Immediate hospital assessment improves chances of saving sight
- Do not drive; seek urgent medical help straight away
