Unequal pupils may indicate physiologic anisocoria, a birth defect; drugs used to treat other eye conditions; or neurological conditions that affect the third cranial nerve, according to The Merck Manual Home Edition. Disorders in the brain that affect the pupils include strokes, bleeding in the brain, infections or tumors.Know More
Physiologic anisocoria is marked by pupils that appear naturally different in size. This condition occurs in 20 percent of the population, and the difference in sizes does not affect how people see. Pupils affected by physiologic anisocoria react to light normally, notes The Merck Manual Home Edition. Eye disorders and drugs used to treat them may cause unequal pupil sizes. Homatropine is used for inflammation of the eye, and pilocarpine treats glaucoma. Both of these drugs may cause pupils to have different sizes. Iritis, or inflammation of the eye, and glaucoma can also make the pupils become unequal.
Strokes and brain hemorrhaging can affect the pathways of the cranial nerves that control muscles and actions of the eye. Brain disorders such as tumors and infections can also affect the pupil sizes, but these are not as common as strokes and bleeding, explains The Merck Manual Home Edition. Other symptoms may be a cause for concern if they appear alongside unequal pupils. These symptoms include droopy eyelids, double vision, loss of vision, headache and eye pain and could be warning signs of a more serious medical condition in the brain.Learn more about Vision
Scleral melanocytosis, amelanotic conjunctival nevi and scleral thinning are three eye conditions associated with gray spots on the whites of eyes, explains EyeSmart. The first two are benign conditions but still require monitoring by an eye health professional because they are associated with potential development of eye diseases.Full Answer >
Thinking about dark places can be enough to dilate your pupils on command. Staring at something in the distance or letting your eyes fall relaxed and unfocused makes your pupils grow. Other methods for dilating your pupils include tensing your stomach or imagining yourself in a daring situation.Full Answer >
An image is formed in the human eye when light passes through the pupil, is refracted by the lens and is absorbed by pigment cells in the retina, altering the pigments and triggering neurons to fire. The particular arrangement of the stimulated cells is interpreted by the brain into a separate image for each eye. The two eyes look at images from slightly different angles, allowing the perception of depth.Full Answer >
The normal range for pupil size is between 2 and 5 millimeters, although the lighting plays a large part in that spectrum. As people age, their pupils tend to become smaller, according to About.com.Full Answer >