(unequal pupil size)
What is Anisocoria?
Anisocoria is simply when your eye's pupils are not the same (equal).
The pupil is an aperture created by the Iris; which dilates and constrict to regulate the amount of light entering the eye.This protect the retina(macula) from direct sunlight burns(UV trauma) that can blind the eye.
Anyone can have pupils that differ in size with no problem.In fact,epidemiologically,one out of five people have pupils that are normally of different sizes.Not withstanding the aforementioned,there may be  clinically cautions for a serious eye problems when seen.Namely;
*A Nervous system problem(tumor)
*A history of damage of the eye
*Risk of having stroke
*A viral infection
*Adie's tonic pupil(When one eye does not respond to light as well as the other pupil )
NOTE:Anisocoria is not a stand alone diagnosis ;A probe of the underlying cause(if organic ) with effective treatment  will automatically correct this condition.
People rarely realize it themselves that they have unequal pupils.They are often rectified by others(Doctors or neighbors ) or noticed by comparing old to recent photos of themselves.
As Clinicians,patients often present other related problems plus these symptoms :
*drooping eyelids(ptosis)
*problems moving eyes( ocular Akinesia)
*reduced sweating
Your optometrist/ophthalmologist will will examine your pupils both in light room and dark room.this will allow him to see how your pupils respond to light.This help diagnose a normal from abnormal pupils.
Instrument : A pen torch (light)
This is an assessment of the pupillary light pathway,both DIRECT response and consensual response are tested.When a bright light is directed into the eye:
1.both direct (constriction of the Ipsilateral iris) and CONSENSUAL  response (constriction of the contralateral iris) occur.
⚠️The consensual response occurs because the two crossing of the fibers in the neural pathway(optic chiasma) in the brain.The nasal retina fibers cross in the chiasm,and approximately half from each protected nucleus cross in the posterior commissure.this allows a photoelectrical stimulation in the Right eye to indirectly stimulate the left eye too and vice versa.
Caution:both pupils should equally and symmetrically constrict under direct photostimulation of one eye and vice versa.(normal)
About 20% of many benign Anisocoria may be caused by asymmetric Supranuchlear inhibition of the  Edinger -Wesphal nucleus.
Look out for Fixed dilated pupil in accidental drug induced mydyiasis.Look out for drug abuse investigation of individuals proffesion or chemical that could exert such effect.pharmceutical agents such as 0.125% Pilcarpine and cocaine abuse.
RAPD(retinal Affarent Pupillary defect) Test:
This test is done to rule out the organic cause of the anisocoria(tumors,aneurysms,or an inflammation (neuritis ).
The patient fixate on a distant object and then the practitioner swings a light from eye to eye several times rhythmically,taking care to illumibnate each pupil for equal length of time,about 2 to 3 seconds.
The below reactions in the picture will be seen and interpreted :

Adie's tonic pupil:pupil becomes small and does not dilate well in dark,hence pupil is larger in light and smaller in darkness.
Honers syndrome:a damage of the sympathetic pathway to the head resulting in ptosis,miosis,and facial anhidrosis(absence of sweat)
Argyl -Robertson syndrome :there are bilaterally small pupils that reduces in size on near objects (Accommodate ) but not constrict when exposed to bright light.
Argyll -Robertson syndrome

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