A Textbook of Clinical Pharmacology and Therapeutics

424 DRUGS AND THE EYE

Posterior cavity

(vitreous humour)

Retinal arteries

and veins

Macula lutea

Central fovea

(II) nerve

Optic disc

(blind spot)

Retina

Choroid

Choroid

Optic portion

of retina

Ciliary

muscle

Ciliary body

Ciliary

body

α-I-

adrenoceptor

Carbonic

anhydrase

Conjunctiva

Canal of

Schlemm

Posterior

chamber

Anterior

chamber

Iris

Cornea

β- 2 -

adrenoceptor

α- 2

adrenoceptor

Ciliary blood

supply

Ciliary

process

Suspensory

ligaments

of lens

Lens

Sclera

Sclera

Superior rectus

muscle

Conjunctiva

Posterior chamber

Anterior chamber

Anterior cavity

(aqueous humour)

Visual axis Light

Pupil

Iris

Lens

Cornea

Sclera

Inferior rectus

muscle

Figure 52.1:The eye. (a) General features and the visual axis. (b) Enlargement to show features of the ciliary body and the circulation of
aqueous humour, and high magnification area detailing the distribution of adrenergic receptors and carbonic anhydrase location.
(Redrawn with permission from Clancy J, McVicar AJ. Physiology and anatomy. London: Edward Arnold, 1995).

Table 52.1:Autonomic pharmacology/physiology of the eye and associated structures

Tissue Adrenergic receptor Response Cholinergic receptor Response

and subtype and subtype

Iris radial muscle α 1 Mydriasis

Iris sphincter muscle – – M 3 Miosis

Ciliary epithelium α 2 /β 2 Aqueous humour production

Ciliary muscle β 2 Relaxation M 3 Accommodation

Lacrimal gland α 1 Secretion M 2 /M 3 Secretion