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The pupil is a hole in the center of the iris which allows light to enter the eye and then moves towards the retina. The iris contains muscle fibers and they control the size of the pupil when necessary. Normally, the size of the pupil reduces when the eye is exposed to bright light and in dark environment the pupil becomes wider in order to allow sufficient reception of available light. There are also other reasons why the pupils change their size. For instance, this occurs when we focus our eyes to something, take certain drugs or are suffering from certain eye conditions.Changes in Pupil Size and Additional Health Issues

Many times pupil dilation may be accompanied by several more symptoms pointing to the presence of certain medical conditions. The problem becomes even more serious if there is uneven response of pupils, i.e. if one is dilated and the other one narrowed.

Drug poisoning and use of drugs is typically associated with pupil dilation and confusion/loss of consciousness, dry mouth, rapid heart rate and slurred speech. Vomiting may occur as well.

If there is change in level of consciousness, changes in mental status and sudden behavioral changes, garbles and slurred speech, paralysis, seizures, severe headache or eye pain, sudden changes in vision, loss of bladder /bowel control and loss of sensation along with the change of the size of the pupils, such individuals require emergency medical assistance.

Drugs and Pupil Dilation

There are different drugs that can cause dilation of pupils as a side effect. Some drugs are, however, exclusively used for dilation of pupils, and they allow an ophthalmologist to have better insight in the inner structures of the eye.

Amphetamines, antihistamines, atropine, cocaine, decongestants, some eye drops like Visine, LSD, marijuana, methamphetamine are all known to cause pupil dilation.

Furthermore, it is essential to take potential poisoning with certain substances into consideration when searching for reasons behind dilated pupils. Pupils are dilated in case of benzene, chloroform, jimson weed and toxic mushroom poisoning.Dilated Pupils and Other Medical Conditions

Dilated pupils are a characteristic of a variety of neurological illnesses as well as eye disorders and diseases.

Patients suffering from disorder of the third cranial nerve and elevated intraocular pressure typically have dilated pupils.

Furthermore, there are brain aneurysms, brain tumors, cerebral edema, head trauma, elevated intracranial pressure, intracranial hemorrhage, stoke etc. as potential underlying causes of dilated pupils.

All in all, if problems with the pupils and their inability to adapt normally or their asymmetrical appearance are accompanied by any additional symptom and sign, a person is due to seek medical assistance immediately.

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