It triggers rapid breathing, increased heart rate and blood pressure, more adrenaline in the bloodstream and dilation of the pupils, which are the black parts of the eye. The dilated pupils make the eyes seem black. They indicate that the person's brain perceives a threat and is preparing to respond with aggression.
It's documented that adrenaline can make the pupil take over the eye. Mania sounds like it's something to do with adrenaline, so I would think the eye is the same color, but the pupil is huge. This creates the all-black eye.”
The pupil can change size with certain emotions, thus changing the iris color dispersion and the eye color. You've probably heard people say your eyes change color when you're angry, and that probably is true. Your eyes can also change color with age. They usually darken somewhat.
A black eye develops when fluids collect in the tissues around the eye. The bruising and blue and purple discolouration are caused by broken blood vessels under the skin. These tissues will usually be swollen too. The eye itself is not usually damaged.
Stimulation of the autonomic nervous system's sympathetic branch, known for triggering "fight or flight" responses when the body is under stress, induces pupil dilation.
Anger is another emotion that can be easily expressed with the eyes. They may narrow and "harden", seeming to pin people with a newfound intensity. Angry eyes are perceived as cold and sharp. They often look as if they're snapping or sparking as they glower, stare, or glare at others.
For example, narrow eyes and tight lips indicate anger. If someone is uncomfortable with something you have said, he will often use a body language tactic called eye blocking.
Dark circles can be a sign of tiredness and a lack of sleep, but they can also result from allergies, thyroid conditions, older age, and other factors. Dark circles under the eyes may look purple or blue to dark brown or black, depending on skin color.
Why do narcissists' eyes go black? They don't change color. Pupils dilate when you are under stress which signifies a mental 'commotion' that is occurring. Since narcissists are generally high-stress type people, their pupils may dilate more than average or when confronted or when under some type of mental distress.
Anger as Seeing Red: Perceptual Sources of Evidence - PMC.
When psychopaths cry, Glass says they will often wipe underneath each eye, one at a time. "When people cry genuine tears they cry with both eyes, and so they will tend to wipe both eyes at once."
One analysis by researchers in 2005 also contrasted core characteristics of women and men with psychopathy. They suggested that women often exhibited traits like debilitating impulsiveness (such as a lack of planning), thrill-seeking in interpersonal relationships, and verbal aggression.
The most common cause of temporary vision loss is reduced blood flow to your eye. You have a large blood vessel on each side of your neck that brings blood from your heart to your eyes and brain. Fatty deposits called plaque may build up in blood vessels and make them more narrow.
A blow to the eye or to the head can cause the skin around the eye to turn purple, blue and black. This happens because skin around the eye is very loose, so fluid fills up underneath, causing swelling and bruising. A blow to the eye can also break the paper thin bones that surround the eye.
Reacting quickly and violently to small problems, e.g. becoming angry when somebody bumps into you. Accusing friends and relatives of disrespecting you or of going behind your back. Finding it difficult to calm the feeling of anger without feeling the urge to express it through displays of anger.
A clenched jaw, intense eye contact, furrowed brows, and reddened skin are facial signs of anger. You might notice these signs when someone is unable to express anger through gestures or words.
The emotion of anger is associated with the choleric humor and can cause resentment and irritability. It is believed that this emotion is stored in the liver and gall bladder, which contain bile. Anger can cause headaches and hypertension which can in turn affect the stomach and the spleen.
The adrenal glands flood the body with stress hormones, such as adrenaline and cortisol. The brain shunts blood away from the gut and towards the muscles, in preparation for physical exertion. Heart rate, blood pressure and respiration increase, the body temperature rises and the skin perspires.
Facial expression of anger
In anger the eyebrows come down and together, the eyes glare, and there is a narrowing of the lip corners. During conscious suppression or unconscious repression of anger, the expression may be less obvious, though the person may show signs of their anger in a split-second micro expression.