From the Guidelines
Tropicamide is a short-acting anticholinergic medication primarily used as a mydriatic and cycloplegic agent in eye examinations, with effects beginning within 20-40 minutes and lasting 4-6 hours, as noted in the most recent study from 2023 1.
Key Points
- Tropicamide works by blocking the muscarinic receptors in the eye, causing pupil dilation (mydriasis) and paralysis of the ciliary muscle (cycloplegia), which allows for better examination of the retina and accurate measurement of refractive errors.
- The typical concentration used is 0.5% to 1%, and it is commonly used before eye examinations, retinal photography, and certain eye surgeries.
- Patients should be aware that tropicamide will cause temporary blurry vision and light sensitivity, so they should arrange transportation after appointments where it's used and bring sunglasses.
- Side effects are generally mild and temporary, including stinging upon application, increased intraocular pressure, and dry mouth, as reported in a study from 2023 1.
- It should be used with caution in patients with narrow-angle glaucoma or those predisposed to this condition, as it can potentially trigger an acute attack, as noted in a study from 2023 1.
Usage and Precautions
- Tropicamide may be used in combination with other agents, such as phenylephrine hydrochloride, to produce adequate dilation and cycloplegia, as reported in a study from 2023 1.
- The use of topical anesthetic prior to the cycloplegic agent reduces the stinging of subsequent eyedrops and promotes penetration of subsequent eyedrops.
- Uncommon short-term side effects of cycloplegic agents may include hypersensitivity reactions, fever, dry mouth, tachycardia, nausea, vomiting, flushing, somnolence, and, rarely, behavioral changes (i.e., delirium).
From the FDA Drug Label
ADVERSE REACTIONS Ocular: Transient stinging, blurred vision, photophobia and superficial punctuate keratitis have been reported with the use of tropicamide. Increased intraocular pressure has been reported following the use of mydriatics. Non-Ocular: Dryness of the mouth, tachycardia, headache, allergic reactions, nausea, vomiting, pallor, central nervous system disturbances and muscle rigidity have been reported with the use of tropicamide. The effect of Tropicamide is to cause mydriasis (dilation of the pupil) as a mydriatic agent, but it also has several adverse effects, including:
- Ocular effects: transient stinging, blurred vision, photophobia, superficial punctuate keratitis, and increased intraocular pressure
- Non-ocular effects: dryness of the mouth, tachycardia, headache, allergic reactions, nausea, vomiting, pallor, central nervous system disturbances, and muscle rigidity 2
From the Research
Effects of Tropicamide on the Eye
- Tropicamide is a mydriatic agent that can cause pupil dilation, with studies showing its effectiveness in achieving mydriasis 3, 4, 5.
- The use of tropicamide can lead to a decrease in the risk of angle closure and significantly raised pressure during dilatation, especially when compared to other mydriatic agents like cyclopentolate 3.
- However, repeated doses of tropicamide can result in reduced mydriasis, with pupils not dilating as well after the second dose as those of control eyes 6.
Comparison with Other Mydriatic Agents
- Tropicamide has been compared to phenylephrine, with studies showing that tropicamide is more effective at inducing pupillary dilation 5.
- The combination of tropicamide and phenylephrine has been shown to be more effective than multiple drops of single eye drops 5.
Effects on Visual Recovery and Retinal Microvasculature
- The use of micro drops of 1% tropicamide has been shown to cause a small but statistically significant improvement in the rate of recovery of distance and near visual acuity 4.
- Pupil dilation using topical 2.5% phenylephrine and 0.5% tropicamide has been shown to result in a small but statistically significant reduction in non-HD ONH whole image and cpCD in healthy eyes 7.