Comprehensive Notes on Cholinergic Agonists for Glaucoma Management

Cholinergic agonists are characterized by the following general properties:
- They are recognized in clinical practice by their green caps.
- They are the oldest class of glaucoma medications, having been in use since the late 1800s.
- They are also referred to as:
- Cholinergics.
- Paris and pathala medics.
- Miotics.
The term "miotic" is a point of professional objection for the speaker, who argues that the term refers to a side effect (pupillary constriction) rather than the primary therapeutic goal, similar to calling carbonic anhydrase inhibitors "tingly fingers."

Cholinergic receptors possess both nicotinic and muscarinic activities.
- Nicotinic activities (associated with Truffaut Nia Morton salon) are categorized as neuro-ophthalmic topics and are not the focus of this discussion.
- Muscarinic mechanisms of action involve specific muscular contractions within the eye:
- Contraction of Longitudinal Muscles: These drugs contract the longitudinal muscles of the ciliary body.
- Trabecular Meshwork Opening: The contraction of these muscles serves to open the trabecular meshwork.
Unique therapeutic status: This is the only class of glaucoma agents that increases trabecular outflow.
- In most glaucoma cases, the underlying pathology is that fluid does not flow normally through the trabecular meshwork into the slums canal.
- Theoretically, this makes cholinergic agonists an ideal class of drugs for treating the root cause of the condition.
Secondary Effects (Non-Pressure Related):
- Circular Muscle Contraction: These drugs contract the circular muscles of the ciliary body, which leads to accommodation. This is particularly problematic for young patients with significant accommodative reserve.
- Pupillary Sphincter Contraction: This leads to meiosis (pupillary constriction). It is important to note that meiosis is not mechanically tied to the pressure-lowering effect of the drug.

Open Angle Glaucoma:
- While effective, they are rarely used for chronic treatment today because they have been supplanted by newer medication classes.
Narrow Angle Glaucoma:
- Used as a temporary measure while patients are awaiting a laser ear ADATA me.
- Chronic use in narrow-angle patients is discouraged because the drug can move the lens iris diaphragm forward, potentially precipitating an acute angle closure.
Plateau Iris Syndrome: Used as a treatment option for this specific syndrome.
Pre-Surgical Application: Used before a laser ear ADATA me to tighten and stretch the iris, facilitating the procedure.

Active Inflammation: These agents are generally avoided in patients with active ocular inflammation.
- Use during inflammation can cause the iris to adhere to the lens, leading to central posterior suny kia.
High Myopia: Patients with high myopia are at an increased risk for retinal detachment when using these medications.

Ocular Side Effects:
- Chronic Meiosis: Prolonged use can cause the pupil to become fixed and unable to dilate.
- Brow Ache: Caused by muscle contraction; this is typically transient and does not cause long-term suffering.
- Accommodative Spasm: Younger patients may experience multiple diopters of induced myopia.
- Retinal Detachment: A significant risk factor, especially in predisposed individuals.
- Iris Cysts: Associated with the use of indirect-acting cholinergics like eka 5:8 iodide, specifically in children.
- Cataracts: Indirect agents can cause cataract formation in adult patients.
- Precipitation of Angle Closure: By shifting the lens iris diaphragm forward.
Systemic Side Effects:
- These are very rare and typically occur during over-treatment, such as during an acute angle closure event where drops like pilocarpine are administered every five minutes.
- It is recommended to lower the intraocular pressure via other means first until it reaches a range where the iris musculature can actually respond to cholinergic stimulation.
- Symptoms include:
- Gastrointestinal (GI) side effects: cramps and diarrhea.
- In your esis.
- Bronchospasm.

Pilocarpine:
- Available in concentrations of $1\%$ , $2\%$ , and $4\%$ .
- The $2\%$ concentration is considered to be at the top of the dose-response curve.
- Dosing frequency: Four times a day (QID).
Carbajal:
- Available in concentrations of $1.5\%$ or $3\%$ .
- Used very rarely, primarily when a patient cannot manage the fourth daily drop required by pilocarpine.
- Dosing frequency: Three times a day.
Eka 5:8 Iodide (Phosphine Iodide):
- A very potent agent that frequently appears and disappears from the market.
- Useful for patients who are poor candidates for surgery but tolerate pilocarpine.
- Dosing frequency: Twice a day, which is a significant clinical advantage.
- Interaction Warning: Pilocarpine and eka 5:8 iodide should not be used together. Pilocarpine will compete for the same receptors and actually diminish the therapeutic effect of the more potent eka 5:8 iodide.
Carping Gel:
- Developed to eliminate the need for QID dosing.
- Retained all the side effects of pilocarpine drops and is now largely off the market or hardly used.

Functional distinction: The only glaucoma drug class that increases conventional/trabecular outflow.
Clinical status: Rarely used for chronic management due to side effects and the burden of QID (four times daily) dosing.
Risk management: Essential to remember they can precipitate angle closure glaucoma despite their role in pre-surgical preparation for laser ear ADATA me.