Glaucoma is a condition that causes intraocular pressure (IOP) to increase and can lead to permanent blindness. Glaucoma may develop suddenly and clear up with treatment (acute) or become chronic and require lifelong management. Miotic treatment causes contractions in the iris sphincter and the ciliary muscle to reduce eye pressure by clearing fluid more rapidly from the eye. Mydriatic medications dilate the pupil for a similar effect.
Mydriatic or miotic eye drops can potentially inhibit visual field loss and slow optic nerve damage to delay the need for surgery.
Types of Medications
There are different types of miotic medications, including pilocarpine, carbachol and physostigmine. Pilocarpine has the fewest side effects and is usually prescribed first. If pilocarpine isn't effective, ophthalmologists typically suggest carbachol, which has similar side effects to pilocarpine but requires an additional wetting agent for application. Physostigmine is a last choice due to its high potential for side effects and unsuitability for long-term use. Cyclopentolate/phenylephrine (Cyclomydril) is the most commonly prescribed mydriatic medication.
Miotic agents typically cause a reduction in night vision acuity, darkening of the vision, irritation and redness. Mydriatic medications cause sensitivity to bright lights and headaches and inhibit the eyes' ability to focus for several hours after application.
When miotic drops are combined with either epinephrine or timolol, the IOP levels decrease faster. Ophthalmologists rarely prescribe two miotic agents together because of the increased risk of side effects and quicker development of immunity to benefits.
Mydriatic and miotic medicines shouldn't be used in conjunction because they have opposite effects and would counter the other's benefits.