Mydriatics: Uses, common brands, and safety info

The term mydriatic refers to a group of drugs that cause dilation of the pupils. The induction of the dilation of the pupil is commonly used to allow for a more in-depth examination of the retina during eye exams. This dilation is also critical during procedures such as cataract surgery to allow easy access to the inner eye. 

Mydriatic agents are some of the earliest discovered pharmaceutical agents. Atropine, one of the most widely used mydriatic agents, was isolated from the Datura plant in the early 1800s. The molecule was researched by many scientists until the laboratory synthesis of atropine was finally complete in 1879. 

There are many different types of drugs that may cause mydriasis, or pupillary dilation. Some are used with the intent to cause mydriasis for a medical purpose, while with others, mydriasis is an unintended side effect of their use. Only your healthcare professional can determine if the use of a mydriatic agent is needed for your condition. We will discuss the properties, brand names, and safety of mydriatic agents here.

Other mydriatics

• Prefrin (phenylephrine)

• Isopto Homatropine (homatropine)

• Tropicacyl (tropicamide)

• Ocu-Tropine (atropine)

• Ocu-Tropic (tropicamide)

• Ocu-Phrin (phenylephrine)

• Ocu-Pentolate (cyclopentolate)

• Neofrin (phenylephrine)

• Mydral (tropicamide)

• Mydfrin (phenylephrine)

• Isopto Hyoscine (scopolamine)

• Cyclate (cyclopentolate)

• Atropisol (atropine)

• Atropine-Care (atropine)

• Altafrin (phenylephrine)

• Ak-Pentolate (cyclopentolate)

• AK-Dilate (phenylephrine)

What are mydriatics?

Mydriatics are drugs that cause the dilation of the pupil. Pupillary dilation is needed to allow for a more detailed examination of the inner eye. Dilating is also necessary in procedures, such as surgery to correct cataracts, in order for the surgeon to have access to the inner eye. Without mydriatic agents, the pupil of the eye typically only dilates in dark environments to allow for more light to the eye and vision adjustment to the dark. In bright light environments, such as direct sunlight, the pupil normally constricts or shrinks to protect the retina. 

Disease, trauma, and the use of some drugs can cause mydriasis even in bright environments, which can be damaging to the retina. For this reason, when your doctor uses mydriatic agents, they will typically keep the room dark and ask you to bring sunglasses to your appointment to wear afterward until the effects of the drug wear off.

How do mydriatics work?

The mechanism of action of each type of mydriatic agent is different depending on the class of medication it is. Anticholinergic agents, also known as parasympatholytics such as atropine, block the muscarinic acetylcholine receptors of the eye. Neurotransmitter activity at the receptors causes pupil constriction, therefore blocking these receptors allows the pupillary muscles to relax which causes dilation of the pupil. Homatropine is a belladonna alkaloid agent which has anticholinergic effects but works differently by blocking the sphincter muscle of the iris and the muscle of the ciliary body to cause dilation. Alpha-adrenergic agonists, also known as sympathomimetics such as phenylephrine, used in the eye directly stimulate alpha receptors causing the conjunctival dilator muscle to constrict, leading to dilation.

Some agents used for mydriasis also cause a cycloplegic effect. This paralysis of accommodation of the ciliary muscle of the lens is known as cycloplegia and is necessary for some surgical procedures. The eye has no ability to adjust to light when the ciliary muscle is paralyzed. 

As a part of mydriasis, mydriatic agents cause the relaxation of the muscles of the eye responsible for your focus, and therefore, blurry vision is common when using these agents.

What are mydriatics used for?

• Mydriasis induction

• Cycloplegia induction

• Iritis

• Cyclitis

• Uveitis

• Moderate amblyopia 

• Ciliary spasm due to corneal abrasion

Types of mydriatics 

Anticholinergics

Anticholinergic agents are inhibitors of autonomic postganglionic cholinergic receptors. These receptors are found throughout the body, including the eye, gastrointestinal system, heart, and other smooth muscles. Specifically, neurotransmitter activity on these cholinergic receptors cause the constriction of the pupillary muscles, narrowing the pupils. Anticholinergics block these neurotransmitters from connecting to these receptors which allow for the relaxation of the pupillary muscles, and therefore the dilation of the pupil. Cycloplegia is caused by anticholinergic agents blocking these same cholinergic neurotransmitters on the ciliary muscle of the lens.

Examples of anticholinergics: atropine, tropicamide, scopolamine, cyclopentolate

Alpha-adrenergics

Alpha-adrenergic agents, sometimes called alpha agonists and a part of the sympathetic nervous system, work on a different muscle of the eye to cause mydriasis. These agents directly stimulate alpha receptors of the eye causing the conjunctival dilator muscle to constrict, leading to dilation of the pupil.

Examples of alpha-adrenergics: phenylephrine

Belladonna alkaloids

Belladonna alkaloids have anticholinergic properties and cause blockage of the receptors of the sphincter muscle of the iris and the muscle of the ciliary body to cause dilation and cycloplegia. The iris sphincter is a component of the parasympathetic nervous system.

Examples of belladonna alkaloids: homatropine

Who can take mydriatics?

Adults

Adult men and women can use mydriatic agents for dilation and cycloplegia. These agents are typically used in a medical office in a light-controlled environment. Due to the fact that your eyes may be sensitive to light and your vision may be blurred, your healthcare professional may suggest having someone else drive you. Sunglasses may also be helpful for the light sensitivity you will experience. These agents should be avoided in patients with synechia (iris adhesion to the cornea) or increased intraocular pressure, as well as those with a known hypersensitivity to any of the agents.

During pregnancy or breastfeeding

Generally speaking, ophthalmically (topical) administered mydriatics (e.g. eye drops and ointments instilled directly into the eye) have minimal systemic absorption and therefore are generally considered safe. Systemically administered agents may not be safe in pregnancy. You should consult your doctor or pharmacist for more detailed information on the agent you are using.

Seniors

Some seniors can safely use mydriatic agents. However, mydriatic agents, specifically anticholinergics, should be avoided in patients with closed-angle glaucoma as they can increase intraocular pressure. In general, phenylephrine products should be avoided in the senior population.

Children

The safety of use of mydriatic agents in children depends on the type of agent, dosage, and age of the child. For instance, atropine is approved in infants as young as 3 months for induction. Anticholinergics should be used cautiously, however, because neonates, infants, and young children are especially sensitive to their effects. Phenylephrine can be used in lower concentrations in infants, but the higher concentrations are only safe in older children. Your child’s ophthalmology professional can provide more information on the safety of these products for your child.

Are mydriatics safe?

Mydriatic recalls

• Bella Pharmaceuticals, Inc.: Voluntary recall due to lack of sterility assurance, February 2018

• Altaire Pharmaceuticals, Inc.: Voluntary recall of multiple ophthalmic products, July 2019

• KRS Global Biotechnology, Inc: Voluntary recall due to lack of assurance of sterility, September 2019

Mydriatic restrictions

Do not take mydriatic agents if you have a history of hypersensitivity reactions to other mydriatics.  

Systemic use of mydriatics such as phenylephrine may be contraindicated in patients with cardiac diseases such as severe or uncontrolled hypertension or ventricular tachycardia. High concentrations of ophthalmic phenylephrine are contraindicated in patients with thyrotoxicosis, including hyperthyroidism. Ophthalmic phenylephrine in the 10% concentration is contraindicated in neonates and infants less than a year old due to its cardiac effects.

It is not recommended to use contact lenses with ophthalmic mydriatic dosage forms.

Avoid the use of atropine and other anticholinergics in closed-angle glaucoma as they will increase intraocular pressure. Anticholinergics may also cause dry eyes and may necessitate the need for lubricant eye drops.

Homatropine, a belladonna alkaloid, is contraindicated in both open-angle and closed-angle glaucoma.

Patients with renal disease may be at an increased risk for systemic accumulation of ophthalmically administered mydriatic drugs.

The effects of mydriatic agents (dilated pupils, blurred vision, light sensitivity, and cycloplegia) can last for up to three days after use. It is generally not considered safe to operate machinery or drive during this period of adverse effects. Sunglasses are recommended to assist with light sensitivity. 

Are mydriatics controlled substances?

No, mydriatics are not controlled substances.

Common mydriatics side effects

• Ocular burning

• Ocular stinging

• Ocular discomfort

• Increased lacrimation

• Photophobia

• Eyelid edema

• Conjunctivitis

• Loss of visual acuity

• Headache

• Hyperemia

• Ocular hypersensitivity

• Rebound miosis

• Tachycardia

• Reflex bradycardia

• Hypertension

• Myocardial infarction/ heart attack

• Ventricular arrhythmia

• Syncope

• Subarachnoid hemorrhage

• Respiratory depression

• Hallucinations

How much do mydriatics cost?

The price of mydriatics can have a broad range, especially for the uninsured. Paremyd, a combination product with amphetamine and anticholinergic, is almost $200 for a standard package. Generic products offer cost savings and may be better covered by your insurance. Visit SingleCare to find your best price prior to filling your prescription. A SingleCare discount card can reduce your prescription cost by as much as 80%.