This can happen due to many reasons, like sudden drop in blood pressure, migraine aura, retina related problems, glaucoma or sudden shock in the body. Whether the reason is small or big, it is important to understand why darkness appears in front of the eyes.

Orthostatic hypotension is a common cause. On standing suddenly, blood pressure falls and due to reduced blood flow to the brain, darkness can appear in front of the eyes. This may cause dizziness, lightheadedness and sometimes even fainting.

Migraine aura can also cause such problems. Before a migraine starts, many people experience flashes of light, jagged lines, or a momentary loss of vision. This is an early sign of migraine.

Transient ischemic attack i.e. mini-stroke can also cause sudden blackout. In this, the brain stops getting blood for some time. Along with this, if symptoms like weakness, numbness or difficulty in speaking are seen then a doctor is needed immediately.

Retinal detachment is a serious condition. In this, the retina starts moving from its place, due to which suddenly floaters, glare or a sensation like curtain falling on one side can be seen. If timely treatment is not received, permanent damage may also occur.

If darkness starts suddenly and repeatedly, is accompanied by pain, or is accompanied by symptoms like weakness and difficulty in speaking, then one should not delay. In many situations, medical examination should be done immediately, hence it is important to get emergency eye check-up done in time.