Eye balls

[Jennifer123]

Does anyone know why someones eye pupil could be larger than the other?

[flirty41]

I think you might be referring to a condition called Adie's pupil, where one pupil is larger than the other. Google Adie's pupil and a whole host of links will appear. It seems to be a nerve disorder which stops the pupil from constricting (ie getting smaller), if I read it right!

[apricot]

Is the size differential permanent or does it change? I have a dog who used to have very different pupil sizes on occasions then it would go back to normal. She had a full neurological check up and was found to be fine. No explanation was ever given by the consultant but it just stopped one day.

[TheParamedic]

A detatched retina can have this effect. Generally caused by a traumatic mechanism of injury (ie car crash, fall from height etc) the afflicted pupil can stay 'frozen' leaving it unable to react to changes in light levels. It is also possible to diagnose a brain bleed by checking a potential stroke victims pupils, if they are not equal in size and reactive to light it may be indicative of a problem. This method also works for traumatic head injuries, but is only another item in a long checklist of tests whilst attempting to ascertain a patients condition.

[craig_edward]

Ok... rare, but Horner's syndrome or a third cranial nerve palsy can cause your pupils to be of different sizes.