Eye-dilating drops make it possible for a medical practitioner to examine the interior of the eye. While people often don't like getting them, it's impossible to do an adequate eye exam without them. Like all medications, dilating drops can cause adverse reactions, some of which can be quite serious.
Most adverse reactions to dilating drops are mild and temporary. Dilating drops sting briefly when they're instilled, and may cause temporary reddening in the eye. The area around the eye and the eyelid may temporarily whiten due to blood vessel constriction, the Pediatric Glaucoma and Cataract Family Association (PGCFA) reports. Vision blurs until the drops start to wear off, because dilation interferes with accommodation, the eye's way of adjusting vision to see objects close up or far away. Near vision is usually more affected than distance vision.
Allergic reactions can occur with any medication, often without warning. Allergic reactions to dilating drops can lead to anaphylactic shock, typified by lightheadedness, fainting, extremely low blood pressure and possibly coma or death. Rashes, itching, hives, facial swelling and difficulty breathing should be evaluated by a health practitioner.
Atropine, a dilating drop that can keep the eye dilated for several days, can cause specific reactions. Facial flushing, rapid heart rate, hot, dry skin and dry mouth, difficulty urinating and hallucinations can occur after atropine dilating drops are given. Other dilating drops can also cause serious reactions, including cardiac problems such as heart arrhythmias, a fast heart rate, confusion, seizures and a rise in blood pressure. Heart attack and fatal subarachnoid hemorrhage occur in rare cases, AgingEye Times reports.
Narrow Angle Glaucoma
Dilating drops can cause a serious complication called narrow angle glaucoma. People who develop narrow angle glaucoma after being given dilating drops have a smaller than normal area to drain fluid from the eye. Fluid must drain out because increased fluid raises the pressure within the eye. Increased intraocular pressure compresses the optic nerve and can cause severe, permanent vision loss. Dilation of the pupil further closes the angle and causes a sudden rise in eye pressure because fluid can't drain out of the eye. Severe pain, redness and vision loss are symptoms of narrow angle glaucoma.
Treatment of adverse reactions to dilating drops depends on the cause. A numbing drop given before the drops are instilled decreases stinging. Artificial tears ease discomfort in a mildly reddened eye. Treatment for other serious complications depends on the symptoms.
Mild allergic reactions respond to antihistamines, while serious reactions may require epinephrine and hospital treatment. Narrow angle glaucoma is a medical emergency that may require medication, laser or surgical treatment.