Small eyes, large pupils in disease
Small pupils - causes and backgrounds
What is the function of the pupil?
The pupil allows light to enter the inside of the eye. Both pupils are usually the same size. When light hits the eye, the pupil shrinks to protect the eye from it. If, on the other hand, your surroundings are dark, your pupils dilate so that more light can enter the eye. The pupil regulates the incidence of light and improves the image quality. It also gets tighter when you try to fixate on an object more precisely.
Anatomically, the pupil is the opening that is enclosed by the iris or iris. Your change is not only influenced by the sight itself, but also by
- Substance abuse
- pupil-altering substances
The iris muscles contract or expand. This leads to small or large pupils. These are necessary so that your eye adapts to the light conditions while seeing.
How and how do small pupils develop?
The reduction in size of the pupils is quite normal when exposed to light, emotions or when an object is fixed. The narrowing caused by closer inspection results in a greater depth of field. The iris contracts strongly. The process is designed to protect the eye when light falls.
However, if the pupils become the size of a pinhead, other causes may also be the case, such as poisoning, the effects of drugs or pupillary disorders. Nerve diseases also reduce the size of the pupil. Eye movements are restricted and signal transmission via the brain is faulty.
What causes and diseases cause small pupils?
Normally and in good health, the pupils are between one and eight millimeters in size. The constriction is called miosis, the enlargement is called mydriasis. The pupils are often larger in youth, but more narrowed in old age. Disorders, allergies, injuries and illnesses influence the pupil motor skills. With tumors, too, the pupils can narrow.
In addition to typical eye diseases, small pupils are also caused by local injuries in the sympathetic vegetative nervous system. Ophthalmology then speaks of Horner's syndrome. With the pupil constriction, the eye appears smaller, as the upper eyelid also hangs down further and the lower eyelid stands up. Horner's syndrome occurs in the following diseases:
- Circulatory disorders
- dilated blood vessels
Which drugs affect pupil size?
Taking drugs has a huge impact on the size of the pupil. Stimulants make it widen, while calming drugs narrow it. Drugs that relax you, wake you up, or just make you feel happy act on both the neurotransmitters in the brain and the muscles of the eye. A narrowing of the pupil occurs with opiates, while it dilates with amphetamines, cocaine, cannabis, LSD or MDMA. Hallucinogens in particular cause a delayed light reaction in the pupil, causing the pupil to dilate or not react.
In which eye disorders do the pupils no longer react at all?
Pupils that no longer respond to light can have other reasons. The term for this is the pupillary rigidity, which can occur in an absolute, reflex or amaurotic manner.
- In the case of absolute pupillary rigidity, the entire pupil motor skills are suspended. Causes can be inflammation, vasodilation, nerve fiber damage or bleeding.
- In reflective pupillary rigidity, the pupil no longer reacts to light stimuli, but becomes narrow when an object is fixed. In addition to bleeding and tumors, the causes are also infectious diseases or alcoholism.
- In amaurotic rigidity, there is a fault in the sensor system. The causes are often inflammation of the optic nerve or a detachment of the retina.
How can an ophthalmologist check symptoms for disorders?
When diagnosing eye diseases, ophthalmologists test the pupil reaction either with light to see whether the pupil narrows when exposed to light, or with special eye drops that cause the pupil to enlarge. This makes it possible to examine the fundus and to better recognize the symptoms. The ophthalmologist illuminates the eye with an ophthalmoscope and identifies symptoms on the retina, the optic nerve or the blood vessels. If the pupils are small, the drops allow examinations in:
- Inflammation of the retina
- Retinal detachment
- Retinal tears
- Macular degeneration
In which feelings do pupils become small or large?
Your eyes and pupil size tell you how you feel. This is because the change in the iris occurs through the unconscious nervous system. If the brain becomes more attentive or switches off accordingly, this affects the eyes. This is not only the case with stress and fear, but also when you are alert or unfocused, tired or bored. A conversation partner who knows their way around immediately notices when you are no longer listening to their report.
Fear and excitement cause the pupil to dilate. Depression, exhaustion, anger and concentration, in turn, reduce them. Calming and pleasant experiences also make the pupil larger, while something unpleasant causes the iris to contract. When communicating with others, humans only perceive many signals subconsciously. In the eyes of others, however, you can very well read what's going on and also recognize when flirting whether the other is really interested, whether you arouse sympathy or antipathy.
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