<ul>
 <li>Neurotransmitters</li>
 <ul>
 <li>Acetylcholine: acts at autonomic ganglia</li>
 <li>Adrenaline (epinephrine)</li>
 <li>Noradrenaline (norepinephrine)</li>
 </ul>
 <li>
 The hydroxylation of tyrosine synthesises DOPA which is then converted to dopamine and finally
 to adrenaline and noradrenaline
 </li>
 <ul>
 <li>Dopamine beta-hydroxylase converts dopamine to noradrenaline</li>
 <li>Adrenaline is formed by methylation of noradrenaline</li>
 </ul>
 <li>
 The action of adrenaline and noradrenaline is terminated by presynaptic reuptake and enzyme
 degradation by monoamine oxidases and catechol-0-methyltransferase (COMT)
 </li>
</ul>

## Adrenergic agonists
<ul>
 <li>Phenylephrine: synthetic sympathimometric</li>
 <ul>
 <li>Acts directly on alpha-receptors</li>
 </ul>
</ul>
<HotTopic>
 
 Phenylephrine cannot&nbsp; produce mydriasis in bright light and produces a rebound miosis.
 Hence it is often combined with cyclopentolate
 
</HotTopic>
<ul>
 <li>Cocaine: works by preventing noradrenaline reuptake into nerve endings</li>
 <ul>
 <li>Can be used to diagnosis pre- or post-ganglionic Horner syndrome (fails to dilate)</li>
 </ul>
 <li>
 Apraclonidine: alpha2-agonist (with weak alpha1 agonist activity, hence use in Horner&rsquo;s)
 </li>
 <ul>
 <li>
 Lowers IOP be decreasing aqueous humour formation (as above, alpha2-receptors stimulate
 aqueous production via adenylate cyclase)
 </li>
 <li>Does not penetrate the blood aqueous barrier</li>
 </ul>
 <li>Brimonidine: selective alpha2-agonist</li>
 <ul>
 <li>
 Used to reduce IOP by reducing aqueous production (by interfering with adenyl
 cyclase) and increasing outflow (by stimulating TM adrenergic receptors,
 increasing cAMP)&nbsp;
 </li>
 <li>Less effective than latanoprost</li>
 <li>
 Causes miosis (can sometimes be utilised intentionally)
 </li>
 <li>Ocular side effects: allergic blepharoconjunctivits, CMO in aphakia</li>
 <li>Contraindicated in heart block/bradycardia</li>
 </ul>
 <li>Hydroxyamphetamine: releases noradrenaline from nerve terminals</li>
</ul>
<HotTopic>
 
 Adrenergic agonists are mydriatic but anticholinergics are both mydriatic and 
 cycloplegic (since the ciliary body is primarily under parasympathetic control)
 
</HotTopic>

## Adrenergic antagonists
<ul>
 <li>Timolol: beta-antagonist (non-selective)</li>
 <ul>
 <li>
 Beta-adrenergic blockade in the non-pigmented ciliary epithelium{' '}
 reduces aqueous production (by disrupting adenyl cyclase action)
 </li>
 <li>
 Side effects: bronchospasm, bradycardia, syncope, CNS depression, may mask hypoglycaemia
 </li>
 <li>10% of patients do not show therapeutic response to beta-blockers</li>
 <ul>
 <li>And the response is reduced in those on systemic beta-blockers</li>
 </ul>
 <li>
 The additive effect of beta-blockers is greatest with topical carbonic anhydrase inhibitors
 </li>
 <li>Betaxolol is a selective blocker but is less effective than timolol</li>
 <li>Carteolol produces less bradycardia than timolol</li>
 </ul>
 <li>
 Guanethidine: inhibits release of noradrenaline from nerve terminals (chemical sympathectomy)
 </li>
 <ul>
 <li>Inhibits Mullers muscle: narrows palpebral fissure</li>
 </ul>
</ul>

Pharmacology

Sympathetic Neurotransmission

Intro

FRCOphth Part 1 Study Notes

Orbit and ocular adnexae

Orbit

Extraocular Muscles

Orbital Blood Vessels

Paranasal Sinuses

Lacrimal Glands

Tear Film

Eyelids

Blinking

Anterior segment - ocular surface

Conjunctiva

Conjunctivitis

Sclera

Cornea

Corneal Structure And Development

Corneal Physiology

AC to Lens

Angle

Ciliary Body

Aqueous Humour Dynamics

Iris

Pupil

Lens

Posterior segment

Choroid

Vitreous

Retinal Macrostructure

Neurosensory Retina

Retinal Pigment Epithelium

Neuroanatomy

Venous Sinuses

Cerebral Ventricles

Cerebral Blood Supply

Supranuclear Gaze Pathways

Head And Neck Autonomic Nervous Supply

Head And Neck Glands

Osteology

Nerves

Muscles And Pharyngeal Arches

Extraocular Nerves

Sensory Nerves

Physiology

Physics Of Blood Flow

Neuronal Control Of Blood Vessels

Oxygen-Haemoglobin Dissociation Curve

Cytochrome p450

Pituitary Gland

Thyroid Hormone Production

Insulin

Glucagon

Parathyroid Hormone

Corticosteroids

Catecholamines

Cardiac Cycle

Renal Physiology

Fluid Balance

Acid-Base Balance

Muscle Physiology

Sensory Fibres

Cutaneous Receptors

Endocytosis

Glycosaminoglycans

Condensed Ocular Biochemistry

Eye Movements

Accomodation

Vision

Visual Cycle And Phototransuction

Visual Pathway

Visual Acuity

Colour Vision

Binocular Vision

Pathology

Collagen

Tissue Damage

Inflammation

Disease Entities

Wound Healing

Thrombosis / Atherosclerosis

Cell Growth

Neoplasia

Histopathology

Nystagmus

Free Radicals And Antioxidants

Immunology

Ocular Immunology

Microbiology

Viral Infections

Bacterial Infections

Fungal Infections

Protozoa

Nematodes

Antimicrobials

Genetics

Chromosomes

Mitosis

Meiosis

Genes

Polypeptide Synthesis

Histones

MicroRNA

Hardy-Weinberg Equilibrium

Mutations

Chromosome Defects

Autosomal Inheritance

X-Linked Inheritance

Mitochondrial Inheritance

Multifactorial Inheritance