Pilocarpine is a prescription medication that is used to treat various eye conditions.
How Does Pilocarpine Work?
Pilocarpine acts on the nervous system and stimulates a portion of the nervous system called the parasympathetic nervous system.
The parasympathetic nervous system is responsible for digestion, constricting pupils, constricting airways, and secreting fluids like saliva and tears.
Pilocarpine acts to stimulate these effects, but when used as an eye drop, its impact is mostly contained to only the eyes.
What Do Pilocarpine Eye Drops Do?
When instilled in the eye, pilocarpine will cause pupil constriction and cause accommodation, or the eyes to harder at near.
When pilocarpine causes the pupil to constrict, it also pulls the trabecular meshwork open, allowing the fluid in the front of the eye to drain easier.
The increased fluid drainage results in a reduction in the intraocular pressure of the eyes.
What Conditions Can Be Treated with Pilocarpine Eye Drops?
Historically, pilocarpine has been mainly used to treat glaucoma. While other medications have become more common, pilocarpine is still prescribed as treatment for glaucoma.
Pilocarpine is also used in preparation for some laser eye surgeries and in cases of Adie’s Tonic Dilated Pupil.
An emerging use of pilocarpine is in presbyopia. Recently, low dose pilocarpine has been approved for daily use to avoid the use of reading glasses.
Pilocarpine in Glaucoma Treatment
Pilocarpine was the first medication approved and used to lower the intraocular pressure in cases of glaucoma.
When pilocarpine constricts the pupil, the anterior chamber angle is opened wider, and fluid can drain easier.
The anterior chamber angle is the limiting factor for draining fluid from the eye and can affect the eye pressure based on how wide open the angle is.
When used effectively, pilocarpine can lower the eye pressure in cases of glaucoma by upwards of thirty percent.
Pilocarpine in Presbyopia Treatment
In 2021, pilocarpine was approved to treat the symptoms associated with presbyopia.
Presbyopia is a normal aging change in which the eyes cannot focus at near as well due to the inflexibility of the crystalline lens.
Treatment options for presbyopia include reading glasses, bifocal glasses, contact lenses, and now low dose pilocarpine.
Pilocarpine causes the pupil to constrict and increases the range of clear vision.
This affect will only last a few hours and is not changing the nature of the condition, only masking the symptoms associated with presbyopia.
Side Effects of Pilocarpine
Pilocarpine is associated with several serious ocular side effects.
The most common side effects are a headache or brow ache, increase in distance blurry vision, and mild burning on instillation.
Less commonly, pilocarpine can cause angle closure attacks and retinal detachments.
Many of the common side effects are due to the increase in accommodation in the eyes causing eye strain and headaches along with blurred vision that mimics nearsightedness.
Angle closure attacks are a rare but serious concern for pilocarpine treatment. If the anterior chamber angle is already narrow, pilocarpine may cause it to close and result in secondary glaucoma.
One of the most severe side effects of pilocarpine is a retinal detachment. As the ciliary muscle contracts when the pupil constricts, it may pull on the peripheral retina and result in a tractional detachment or a retinal tear.
The presence of these side effects necessitates regular eye examinations for anyone using pilocarpine eye drops.
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