Essentials of Ophthalmology

For Medical School and Beyond

Ray Manotosh, Victor Koh

• Editorial: WSPC
• Año: 2018
• ISBN:
  9789813275614
• Categoría: Medicine
• Categoría: Opthalmology & Optometry

Essentials of Ophthalmology: For Medical School and Beyond is a concise reference text for the medical undergraduates and residents, but the contents will also benefit family physicians who really are the first line of eye-care givers in the community.

Highly illustrated with 200 colour clinical pictures and illustrations, the book is written by the multi-disciplinary faculty of the Department of Ophthalmology, National University Health System, Singapore. The authors constantly asked themselves 'how much is too much' and deliberately attempted to weed out any 'excess' for the benefit of the target readers. The content is written in a point format with lucid language.

Emphasis has been focused on information that constitutes essential ophthalmic 'core conditions and problems' of the current medical undergraduate curriculum. Every section in the book has 'learning objectives' and a 'take home message' to facilitate quick learning. The book embraces a practical guide to the study of ocular diseases, basic methods of investigations and treatment where applicable.

Contents:

• Basic Anatomy of the Eye, Adnexa and Visual Pathways (Jeyabal Preethi, Koh Teck Chang Victor)
• Cornea and External Eye Diseases (Chai Hui Chen Charmaine, Anna Marie Tan Wee Tien, Ray Manotosh)
• Cataract (Chai Hui Chen Charmaine, Anna Marie Tan Wee Tien, Ray Manotosh)
• Glaucoma (Koh Teck Chang Victor, Chen Ziyou David)
• Uveitis (Chan Hwei Wuen, Dawn Lim Ka-Ann)
• Vitreoretinal Disorders (Yuen Yew Sen, Paul Zhao Song Bo)
• Oculoplastics (Stephanie Ming Young, George Thomas Naveen, Shantha Amrith, Gangadhara Sundar)
• Paediatric Ophthalmology and Strabismus (Lam Sing Harn Janice, Cheryl Ngo Shufen)
• Neuro-Ophthalmology (Lin Hui'en Hazel Anne, Clement Tan Woon Teck)
• Principles and Practice of Low Vision Rehabilitation (Daniel Bohan)
• Clinical Approaches:
  • Approach to Leukocoria (Lam Sing Harn Janice)
  • Clinical Pathway for Chronic Visual Loss (Jeyabal Preethi, Koh Teck Chang Victor)
  • Clinical Pathway for Acute Visual Loss (Lin Hui'en Hazel Anne)
  • Diagnostic Flowchart in an Acute Red Eye (Chai Hui Chen Charmaine, Anna Marie Tan Wee Tien, Ray Manotosh)
  • Neuro-ophthalmology Approaches (Lin Hui'en Hazel Anne)
  • Pupil Examination (Lin Hui'en Hazel Anne)

• Clinical Examinations:

• Approaches to Visual Acuity (Jeyabal Preethi, George Naveen Thomas)
• Cover Test (Lam Sing Harn Janice)
• Normal Fundus Examination (Yuen Yew Sen)
• Visual Fields by Confrontation (Lin Hui'en Hazel Anne)

Readership: Medical undergraduates, residents, primary eye-care providers.
Key Features:

• The book is designed to incorporate knowledge and skills to prepare the undergraduate medical students for their NUS rotation within Ophthalmology
• The content is written in summarized point format with lucid language that is supplemented with more than 200 high resolution clinical pictures and illustrations
• Atlas of coloured images which illustrates concepts, anatomy, conditions, treatment and common complications related to the Asian population

Chapter 1

BASIC ANATOMY OF THE EYE, ADNEXA AND VISUAL PATHWAYS

1.1Basic Anatomy

Learning Objectives

Understand the basic anatomical structures of the globe.

The external structure of the globe comprises the sclera (outer most layer), uveal tissue (middle layer) and retina (innermost layer). Refer to Fig. 1.1.

Sclera

•Strong and dense coat protecting the intraocular contents

•Anterior 1/6th — transparent cornea, posterior 5/6th opaque sclera. Junction is called limbus

Fig. 1.1. Coronal section of the eyeball showing the various structures.

•Thickness:

Thickest posteriorly (1 mm) and gradually becomes thinner upon tracing anteriorly

Thinnest at the level of insertion of extraocular muscles

•Lamina cribrosa: sieve-like part of sclera through which optic nerves exits the globe

Uveal tissue

•Supplies nutrition to various structures of the eyeball

•From anterior to posterior, it consists of iris, ciliary body and choroid

•Functions:

Iris: iris colour varies among different individuals depending on the amount of melanin. Controls amount of light entering the eye

Ciliary body: aqueous humour production, accommodation

Choroid: supplies oxygen and nutrition to outer layers of retina

Retina

•See the sections below for more details

Take home messages

The cornea and sclera forms the outermost wall of the globe and forms a protective cover over the intraocular structures.

1.2Cornea

Learning Objectives

Understand the components and functions of the different layers of the cornea.

The cornea is the transparent outermost covering of the eye and is the most important refractive medium of the eye (Fig. 1.2 and Fig. 1.3).

Fig. 1.2. Illustration of slit-lamp beam image of the anterior segment. The first broad slit beam corresponds to the cornea and the second narrow beam corresponds to the anterior surface of the lens.

Fig. 1.3. Cross-section of the cornea and the 5 layers.

The 5 layers of the cornea are composed of:

Epithelium

•5 layers of cells and 50-60 microns thick

•Approximately 7 days for complete turnover of corneal surface epithelium

•Production of new cells occurs at the limbus and grows centripetally from the periphery towards the centre

•Nerve endings of sensory nerve fibres run between the epithelial cells

Bowman’s Layer

•Acellular layer

•8–12 microns thick

Stroma

•Forms 90% of corneal thickness

•Multiple lamellae of compact collagen fibrils

•Uniform spacing of collagen fibrils maintain the transparency

Descemet’s Membrane

•Basement membrane of the endothelium

•10 microns thick

Endothelium

•Single layer of flattened cells

•Important in the transport of fluid, keeping the cornea dehydrated and transparent

•Does not regenerate

•Physiological rate of loss of cells with age

Nerve Supply of the Cornea

•From the ophthalmic division of the trigeminal nerve (mainly...