Transcript PHARMACOLOGY OF THE EYE

PHARMACOLOGY OF THE
EYE
Prepared By:
Dr./ Rehab Lashine
Pharmacology Department
Physiological Anatomy of the Eye
THE ANT.CHAMBER OF THE EYE
The Ciliary Body
The Pupil
Pupillary Muscles
Mydriasis
Miosis
Effect of Miosis and Mydriasis on
Acquous Humor Drainage
Accomodation
Autonomic Nerve supply of the Eye
Parasympathetic:
1- Bl.Vs. …Conjuctival VD ( Oculomotor)
2- Ciliary mm.. (Accomodation)
(Oculomotor)
3- Sphincter pupillae(Miosis) (Oculomotor)
4- Increased lacrimation…..7th vranial n.
(N.B.: Stim. Of the nic. Rec. causes twitches of
eye lid mm.)
•Sympathetic
1- Bl.Vs.( Conjunctival VC)………α1
2- Dilator Pupillae ( Mydriasis)…….. α1
3- Levator palpebrae & Muller’s m.(Exophthalmus
& widening of the palpebral fissure)…..
4- Ciliary mm (relaxation)……. β2
5- Lacrimal glands (lacrimation)……… α1
6- α & β rec. in the Bl.vs. of the ciliary
processes….help in regulation of aqueous
humour formation
Light Reflex
Corneal Reflex
Drugs Acting on the Eye
I- Drugs affecting the size of the pupil:
 Miotics
 Mydriatics
II- Drugs Affecting Accomodation….Cycloplegics
III- Drugs affecting the IOP (intraocular pressure)
IV- Local Anesthetics
V- Antiallergic agents
VI- TTT of Eye Infection
Miotics
M3 rec.: Parasympathomimetics
α1 blockers:
Sympatholytics(e.g.Phenoxybenzamine)
Central : Morphine ( ↑oculomotor nucleus)
USES:
-Glaucoma
-Counteract action of mydriasis
- To break adhesions
Mydriatics
 Active:
- Sympathomimetics….(Mydriasis without Cycloplegia or loss of
light reflex)
- Local anesthetics…..(Cocaine) (Mydriasis without Cycloplegia or
loss of light reflex ).
 Passive:
- Anticholinergics……(Mydriasis with Cycloplegia & loss of light
reflex) except Eucatropine (doesn’t cause cycloplegia).
 Ganglion Blockers …...(Mydriasis with Cycloplegia )
 Central
USES:
Fundus Exam, Therapy of acute Iritis, Breaking Adhesions
Drugs Affecting Accomodation
Drugs causing Accomodation to near
objects:
- stim. of ciliary mm:
Parasympathomimetics
Cycloplegics: drugs causing paralysis of
ciliary mm…..loss of
accomodation…fixation of vision for far
vision: Parasympatholytics (EXCEPT
EUCATROPINE)
N.B.:
Sympathomimetic mydriatics are safely
used in adults > 40 years in whom
Atropine have the risk of causing
dangerous rise in IOP.
Therapeutic uses of Cycloplegic drugs:
1- Ttt of Iridicyclitis
2- Ttt of choroiditis
3- Measurement of refractive errors
Drug Therapy of Primary Open Angle
(chronic simple) Glaucoma
A) Miotics: They act mainly by↑ the acqueous
outflow.
1- Direct : pilocarpine.
2- Indirect: choline esterase inhibitors
B) Sympathomimetics: ↓ acq.humour production, &
↑ outflow
C) Β-adrenoceptor blocking agents: ↓ acq.humour
production…….Timolol, befunolol
D) Oral Agents: Carbonic Anhydrase inhibitors. ↓
acq.humour production…..Acetazolamide
Drug Therapy of acute angle closed
(congestive) glaucoma
 Dehydrating agents: IV infusion Of Hypertonic
solution ( Mannitol, Glycerol)
 Oral Acetazolamide
 Topical miotics: e.g.: pilocarpine
 Analgesics: pethidine or morphine (for pain)
Drug used in treating inflammatory
and allergic eye conditions
1- Conjunctivitis: can be ttted by:
A- Penicillin G, chloramphenicol ( Acute purulent
conj.)
B- Sulphacetamide (eye drops)..for trachoma
C- Tetracycline ….for chronic follicular
conjunctivitis
D- Vidarabine, or Acyclovir for Herpes simplex
keratitis
E- Topical steroids for chronis puppillary conj.
Drug used in treating inflammatory
and allergic eye conditions( Cont.)
2- Glucocorticoids: to suppress inf., and
allergy
3- Topical Antihistaminics: (eye drops), in
allergies
4- Sodium cromoglycate: ( for ttt. Of spring
catarrh, vernal keratoconjunctivitis)
5- Astringents : Zinc Sulphate ( angular
conj.)
Harmful drugs for the Eye
1- Drugs that ↑ IOP:
A- Mydriatic cycloplegics, tricyclic antidepressants
B- Chronic steroid use
2- Cataractogenic drugs: steroids, phenothiazines,
heavy metals…
3- Drug-induced retionopathies: ethanol, methano,
indomethacin,steroids
4- Drugs causing corneal deposits: Amiodarone,
chloroquine…
5- Oculomucocutaneous syndrome ( Conj. Fibrosis,
corneal opacities,and dimnished tear secretion) e
practolol
6- O2 : 40 % for prolonged periods in premature infants
causes Retrolental fiboplasia
Experiment