In March 1991, a team of London ophthalmologists and visual scientists discovered one-fifth of people have unequal pupil size. The condition is scientifically referred to as anisocoria and is often asymptomatic. Determining which pupil is abnormal has to be done through a clinical process under controlled conditions.
In some circumstances, children are born with unequal pupils, called physiological anisocoria. The condition is not life-threatening, and people with this type of anisocoria can live normally and have vision equivalent to those unaffected by the issue. The difference between the normal pupil and the other ranges between 25% to 50% at any given light stimulus.
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