7/29/2019 Glaucoma Pharmacology

1/2

1

Pharmacology of the Eye

Edward JN Ishac

Department of Pharmacology and Toxicology

Medical College of VirginiaCampus of Virginia Commonwealth UniversityRichmond, Virginia, USA

Smith Building, Room 742eishac@hsc.vcu.edu8-2127 8-2126

Pharmacology of the Eye

The eye is a good example ofan organ with multiple ANS

functions, controlled by several different autonomicreceptors. (Katzung)

Increased intraocular pressure: Untreated blindness

Glaucoma:

- Open-angle (wide, chronic) treated with beta-

blockers and other agents

- Closed-angle (narrow-angle) dilated iris can

occlude outflow. Pilocarpine or surgical removal of

part of iris (iridectomy)

GlaucomaIncreased intraocular pressure: Untreated blindness

Glaucoma:- Open angle (wide, chronic) treated with beta-blockers and other agents- Closed-angle (narrow-angle) dilated iris can occlude outflow

Pilocarpine or surgical removal of part of iris (iridectomy)

Glaucoma treatment

1. -Agonist: Outflow2. M-Agonists: Outflow3. -Blocker:Secretion4. 2-Agonist: Secretion

5. Prostaglandins: Outflow6. Carbonic acid inhibitors: Secretion

Ach effects on smooth muscle in the eye

Contraction of sphincter muscle miosis

Contraction of ciliarymuscle for near vision

Actions on the EyeGlaucoma treatment

1. -AgonistOutflow

2. M-Agonists

Outflow

3. -BlockerSecretion

4. 2-AgonistSecretion

5. Prostaglandins Outflow

6. Carbonic acidinhibitors

Secretion

Drugs used in glaucoma

Cholinomimetics

Pilocarpine, physostigmine,echothiophate

Ciliary muscule contraction opening of trabecular

meshwork outflow

Topical

Alpha Agonists: Unselective:Epinephrine

Outflow Tropical

Alpha2-Selective Agonists:

Apraclonidine

Aqueous secretion from theciliary epithelium

Topical

Beta-Blockers :Timolol, betaxolol, carteolol

Aqueous secretion from theciliary epithelium

Topical

Secretion due to lack ofHCO3

-

OralTopical

Diuretics: Carbonic acid inhi b.Acetazolamide, Methazolamide

Dorzolamide, Brinzolamide

Outflow TopicalProstaglandins:

Latanoprost

7/29/2019 Glaucoma Pharmacology

2/2

2

Innervation of the iris

Clinical Setting Drug Pupillary Response

Normal Sympathomimeticie. phenylephrine

Dilation (mydriasis)

Normal Parasympathomimeticie. pilocarpine

Constriction (miosis)

Normal Parasympatholytic

ie. atropine

Mydriasis,

cyclopegia

Horners syndrome Cocaine 4-10% No dilation

P re ga ng li on ic H orn er s Hy droxy amph etami ne Di la ti on

Postgangl ioni c Horner s Hydroxyamphetamine No di la ti on

Adies pup il Pilocarpine 0.05-0.1% Constriction

Normal Opioids (oral or

intravenous)

Pinpoint pupils

Effects of pharmacological agents on the pupil

Eye - Horners Syndrome

Destruction of Sympathetic innervation to the iris

- loss of preganglionic fibers- loss of postganglionic fibers

- parasympathetic innervation left unopposed

Horners Syndrome (note sagging left eyelid and miosis)

Adies Pupil & Iritis

Iritis

Muscarinic blocker to dilate pupil

to prevent attachment to lens.Steroid to treat inflammation.

Adies PupilPoor light reflex

Topical scopolamine drops on pupil diameter and accommodation. inthe normal human eye. One drop (0.5%) at zero time and 30 min.