Rapid Ophthalmology E-Book

Zahir Mirza

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Rapid
• Sprache: Englisch

Seitenzahl: 133

Veröffentlichungsjahr: 2013

Beschreibung

A brand new title in the Rapid series, providing a concise, structured approach for students preparing for ophthalmology examinations

Presents a thorough foundation of ophthalmology knowledge, emphasising clinically relevant information, in the familiar 'Rapid' series format where diseases are presented in alphabetical order so aiding quick look-up of conditions

Ideal for use in busy clinical settings, such as clinics and hospital wards, while on rotation

Includes a companion website at www.wileyrapids.com/ophthalmology containing a range of clinical images in PowerPoint format.

This title is also available as a mobile App from MedHand Mobile Libraries. Buy it now from iTunes, Google Play or the MedHand Store.

Leseprobe

Contents

Cover

Dedication

Title Page

Copyright

Preface

Acknowledgements

Abbreviations

About the companion website

Basic anatomy and physiology

Osteology of the orbit

Orbital fissures

Optic canal

The globe

Cornea (Figure 2)

Anatomical terms

Retinal overview

Layers of the retina

Blood supply to the eye

Ciliary body and lens

Trabecular meshwork

Aqueous humour flow

Tears

Vitreous humour

Ocular muscles (origin / insertion / primary actions [Figure 5])

The visual pathway (Figures 6 and 7)

Pupillary reflexes

Pupil defects

Ophthalmological assessment

History taking

Examination

Examination techniques

Objective structured clinical examination (OSCE) section

Differentials

Watery eye

Proptosis

Optic disc atrophy

Toxic optic neuropathy

Swollen optic discs

Ptosis

The red eye

Differential flow charts

Diseases

Age-related macular degeneration (AMD), dry

Age related macular degeneration, wet

Amaurosis fugax

Amblyopia

Blepharitis

Cataract, age-related

Cataract, congenital

Cavernous sinus syndrome

Cellulitis, orbital

Cellulitis, preseptal

Chemical injury to the eye

Conjunctivitis, bacterial and chlamydial

Conjunctivitis, other (including ophthalmia neonatorum)

Conjunctivitis, viral

Cranial nerve III (CNIII) palsy

Cranial nerve IV (CNIV) palsy

Cranial nerve VI (CNVI) palsy

Cytomegalovirus (CMV) retinitis

Dacrocystitis

Diabetic retinopathy

Ectropion

Endophthalmitis

Entropion

Episcleritis

Exposure keratopathy

Eye trauma

Eye tumours

Giant cell arteritis (GCA) (including Wegener's granulomatosis and Behçet's disease)

Glaucoma, acute primary angle-closure

Glaucoma, chronic open angle

Herpes zoster ophthalmicus (HZO)

Horner's syndrome

Hypertensive retinopathy

Keratitis, bacterial

Keratitis, herpetic

Keratoconjunctivitis sicca

Keratoconus

Lid lumps, basal cell carcinoma

Lid lumps, chalazion

Lid lumps, other (benign)

Lid lumps, other (malignant)

Migraine

Multiple sclerosis (MS)

Pinguecula

Posterior vitreous detachment (PVD)

Pterygium

Retinal artery occlusion

Retinal detachment

Retinal vein occulsion

Retinitis pigmentosa and other inherited retinal dystrophies

Retinoblastoma

Retinopathy of prematurity (ROP)

Sarcoidosis (and Tuberculosis)

Scleritis

Squint (strabismus), childhood

Thyroid eye disease

Uveitis, anterior

Uveitis, intermediate

Uveitis, posterior

Glossary

Index

To my supportive and ever thoughtful wife.

Zahir Mirza

This edition first published 2013 © John Wiley & Sons, Ltd

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Library of Congress Cataloging-in-Publication Data

Mirza, Zahir. Rapid ophthalmology / Zahir Mirza ; editorial advisor, Andrew Coombes. p. ; cm. – (Rapid series) Includes bibliographical references and index. ISBN 978-0-470-65691-4 (softback : alk. paper) I. Coombes, Andrew. II. Title. III. Series: Rapid series. [DNLM: 1. Eye Diseases–Handbooks. 2. Diagnostic Techniques, Ophthalmological–Handbooks. WW 39] RE720 617.7–dc23 2013003061

A catalogue record for this book is available from the British Library.

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.

Cover image: © Pasieka/Science Photo Library Cover design by Visual Philosophy

Preface

Rapid Ophthalmology is crafted to offer a concise, clear and accessible overview of ophthalmology. Primarily, the book is aimed at medical students, especially to complement ophthalmology firms and exam revision. It is not designed to be a textbook but rather a source for quickly finding facts about ophthalmology. For example, one could easily have a copy in clinic and look up a disease using a patient's presenting symptoms. Whilst revising for exams the book provides an extremely efficient resource with sections tailored specifically towards differential diagnosis, assessment and OSCE exams.

This book, however, has a value beyond most revision textbooks. It is a book that will not be defunct on the shelves of a junior doctor or even a general practitioner. I have intended this book to be such that it that contains the information needed for the nonspecialist to diagnose, manage and refer those presenting with ophthalmological conditions.

Finally, there is the cohort who desire to pursue ophthalmology as a career. This book would serve that cohort well as they begin to attain knowledge in preparation for a career in ophthalmology.

Zahir Mirza

Acknowledgements

Thank you to Zainab Laftah who authored the two sections, ‘Lid lumps, basal cell carcinoma’ and ‘Lid lumps, other (malignant)’.

Abbreviations

Denotes that an urgent referral is requiredA&EAccident and emergencyAAIONAnterior ischaemic optic neuropathyACEAngiotensin converting enzymeAMDAge-related macular degenerationANAAnti-nuclear antibodyANCAAnti-neutrophil cytoplasmic antibodiesBCCBasal cell carcinomaBPBlood pressureBRVOBranch retinal vein occlusionCADASILCerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathyCFCount fingers visual acuityCNCranial nerveCNSCentral nervous systemCRAOCentral retinal artery occlusionCRPC-reactive proteinCTComputerised tomography scanCMVCytomegalovirusCRVOCentral retinal vein occlusionDMDiabetes mellitusdsDNADouble stranded deoxyribonucleic acidDVLADriver and Vehicle Licensing AgencyECGElectrocardiographyERDExudative retinal detachmentESRErythrocyte sedimentation rateFBCFull blood countFFAFundus fluorescein angiographyGCAGiant cell arteritisGCLGanglion cell layerHAARTHighly active antiretroviral treatmentHLAHuman leukocyte antigensHMHand movements visual acuityHSVHerpes simplex virusHZOHerpes zoster ophthalmicusILMInner limiting membraneIOInferior obliqueIOPIntraocular pressureIRInferior rectusITUIntensive care unitLRLateral rectusM,C &SMicroscopy culture and sensitivityMRMedial rectusMRAMagnetic resonance angiographyMRIMagnetic resonance imagingNANoradrenalineNFLNerve fibre layerNPLNil perception of light visual acuityNSAIDsNonsteroidal anti-inflammatory drugsNVDNeovascularization at the discNVENeovascularization elsewhereODOmni dei (once a day)ONLOuter nuclear layerOLLOuter limiting layerOSCEObjective structured clinical examinationPCRPolymerase chain reactionPIPeripheral iridotomyPLPerception of light visual acuityPMRPolymyalgia rheumaticaPRLPhotoreceptor layerPVDPosterior vitreous detachmentRAPDRelative afferent papillary defectRFRheumatoid factorROPRetinopathy of prematurityRPERetinal pigment epitheliumRRDRhegmatogenous retinal detachmentSCCSquamous cell carcinomaSOSuperior obliqueSRSuperior rectusTBTuberculosisTORCHToxoplamosis, other, rubella, cytomegalovirus, herpesTRDTractional retinal detachmentU&EUrea and electrolytesUVUltravioletVEGFVascular endothelial growth factorVZVVaricella-zoster virus

About the companion website

This book is accompanied by a companion website:

   www.wileyrapids.com/ophthalmology

The website contains additional ophthalmic images in PowerPoint format for you to download.

Basic anatomy and physiology

Note that anatomical layers are described in order from the outer surface of the eye to the inner core.

Osteology of the orbit

ORBITAL FLOOR

Maxilla, zygoma, palatine bone.

ORBITAL ROOF

Frontal bone, lesser wing of sphenoid.

MEDIAL WALL

Maxilla, lacrimal bone, ethmoid, body of sphenoid.

LATERAL WALL

Zygomatic bone, greater wing of sphenoid.

Orbital fissures

Superior orbital fissure (Figure 1)

TRANSMITS

Lacrimal nerve

Frontal nerve

Trochlear nerve

Superior division of oculomotor nerve

Nasociliary nerve

Inferior division of oculomotor nerve

Abducent nerve

Superior ophthalmic vein

Inferior ophthalmic vein

FIGURE 1 Diagram of the right orbit showing structures passing through the superior orbital fissure (cross section with the globe not included).

Inferior orbital fissure

TRANSMITS

Infraorbital nerve

Zygomatic nerve

Branches from the pterygopalatine ganglion

Optic canal

TRANSMITS

Optic nerve

Ophthalmic artery

The globe

DIMENSIONS

Approximate sphere of 2.5 cm diameter

Axial length 24 mm

Volume 5.5 cm3

LAYERS

Superficial to deep: corneoscleral, uveal tract, neural layer.

Cornea (Figure 2)

DIMENSIONS

Vertical diameter 10.6 mm

Horizontal diameter 11.7 mm

LAYERS

Superficial to deep; corneal epithelium, Bowman's layer, stroma, Descemet's membrane, corneal endothelium.

SENSORY INNERVATION

Ophthalmic division of the trigeminal nerve.

FIGURE 2 Diagram of a cross-section through the cornea.

Anatomical terms

ORBITAL SEPTUM

Layer of fascia within the eyelids arising from the periosteum of the orbital rim.

LIMBUS

Junction between cornea and sclera.

UVEAL TRACT

Comprises the iris, ciliary body and choroid.

CHOROID

Vascular connective tissue between the sclera and retina. It nourishes the outer third of the retinal. The fovea is dependent on this blood supply for nourishment.

ANTERIOR SEGMENT

Portion of the eye between the cornea and the anterior surface of the vitreous humour.

POSTERIOR SEGMENT

Posterior two-thirds of the eye that contains the vitreous humour, optic disc, retina, most of the sclera and choroid.

ANTERIOR CHAMBER

Formed by the cornea anteriorly and the iris posteriorly.

POSTERIOR CHAMBER

Formed by the iris anteriorly and the lens posteriorly.

MACULA LUTEA

Yellow area at the centre of the posterior retina that gives rise to fine vision owing to a high concentration of cone receptors.

FOVEA CENTRALIS

A depression within the centre of the macula; it provides the most distinct vision as it has the highest density of cone receptors. Inner retinal layers are displaced laterally, hence the depression.

OPTIC DISC

The optic nerve and central retinal vessels enter and leave the globe at this site. There are no photoreceptors at the optic disc, hence there is no visual perception of light falling onto this region. Therefore this area gives rise to the blind spot.

Retinal overview

FIGURE 3 Schematic diagram showing clinical terms used to describe regions of the retina.

Layers of the retina

Lying on the retinal pigment epithelium (RPE) are three cell types in series that form the neurosensory retina; photoreceptive rods and cones, interneurones and ganglion cells. The RPE provides physiological support to the overlying neurosensory retina. The neurosensory retina converts light to neural impulses.

Figure 4 is a picture, obtained from ocular coherence tomography, that shows almost histological anatomical detail of retinal layers.

FIGURE 4 Ocular coherence tomography scan of the retina.

RPE – retinal pigment epithelium (and Bruch's membrane); PRL – photoreceptor layer; OLL – outer limiting layer; ONL – outer nuclear layer; GCL – ganglion cell layer; NFL – nerve fibre layer; ILM – inner limiting membrane.

Blood supply to the eye

Branches of the ophthalmic artery, which is the first cavernous branch of the internal carotid artery, supply the eye (important branches listed below):

Central retinal artery – supplies the inner two-thirds of the retina; however, there are no capillaries from branches of this artery supplying the fovea.

Short posterior ciliary arteries – supply the choroid.

Long posterior ciliary arteries – supply the iris and ciliary body.

Lacrimal artery – supplies lacrimal gland and eyelids.

Ciliary body and lens

This structure joins the choroid to the iris and features specialized surface folds (ciliary processes) that secrete aqueous humour. Through fine filaments (zonules) it supports the lens. Contraction of the ciliary body's muscular component relaxes the zonules and causes the lens to assume a more convex shape and thus allows focusing for near vision (accommodation). The lens is a transparent structure contained in an elastic capsular membrane located posterior to the pupil and iris and anterior to the vitreous.

Trabecular meshwork

Located within the angle between the cornea and iris, this structure is responsible for draining 90% of the aqueous fluid.

Aqueous humour flow

Aqueous humour flows from the posterior chamber, through the pupil and into the anterior chamber. It is taken up by the trabecular meshwork which drains aqueous filled vacuoles into a collecting channel known as Schlemm's canal. These drain into the vortex veins that contribute to the venous drainage of the eye.

Tears

Every blink recreates a three-layer tear film that coats the ocular surface.

From anterior to posterior:

Lipid (from eyelid Meibomian glands)

Aqueous (from the lacrimal gland and accessory conjunctival lacrimal glands)

Mucin (from conjunctival Goblet cells)

Vitreous humour

The transparent gel-like substance that occupies the posterior segment of the eye. It is composed 99% of water with collagen, hyaluronic acid and other proteins forming the remainder.

Ocular muscles (origin / insertion / primary actions [Figure 5])

Superior rectus (SR)

Origin – common tendinous ring

Insertion – sclera

Innervation – cranial nerve III (superior division)

Primary action – elevation of the globe

Inferior rectus (IR)

Origin – common tendinous ring

Insertion – sclera

Innervation – cranial nerve III (inferior division)

Primary action – depression of the globe

Medial rectus (MR)

Origin – common tendinous ring

Insertion – sclera

Innervation – cranial nerve III (inferior division)

Primary action – adduction

Lateral rectus (LR)

Origin – common tendinous ring

Insertion – sclera

Innervation – cranial nerve VI

Primary action – abduction

Superior oblique (SO)

Origin – sphenoid bone; however, its functional origin is from the trochlea which acts like a pully

Insertion – sclera

Innervation – cranial nerve IV

Primary action – intorsion (the secondary action is depression, especially in the adducted position)

Inferior oblique (IO)

Origin – anterior orbital floor

Insertion – sclera

Innervation – cranial nerve III (inferior division)

Primary action – extorsion (the secondary action is elevation in adduction)

FIGURE 5 Schematic diagram using a lateral view to show the approximate insertions of extraocular muscles onto the globe. Note that a portion of the lateral rectus has been removed in this diagram in order to show the insertions of the oblique muscles. Also, the medial rectus inserts onto the medial aspect of the globe thus its insertion cannot be visualized from this view.

The visual pathway (Figures 6 and 7)

The nasal retinal receives light from the temporal visual field and the temporal retina receives light from the nasal visual field. Photoreceptors within the retina act as the first-order neurones in the visual pathway. These then synapse with bipolar cells (second-order neurones) which synapse with ganglion cells (third-order neurones). The optic nerve contains axons from these ganglion cells.