THE EYE

The anatomy and physiology of the eye is summarized in Figure 16.3.

The red eye

Many patients with a red eye will have simple benign conditions (Table 16.2). However, other conditions can rapidly lead to loss of Vision which may be permanent and these patients must be referred urgently (i.e. same-day) to a specialist (Table 16.3). Slit lamp examination and measurement of intraocular pressures will often be performed under specialist care after onward referral. The management of a patient presenting with a red eye and a history of trauma or foreign body hitting the eye is beyond the scope of this chapter and is not discussed further.

Conjunctivitis does not usually need referral for a specialist opinion unless the symptoms continue for more than 2 weeks or the eye becomes painful or Vision decreases. Bacterial conjunctivitis is treated with a topical broad-spectrum antibiotic such as chloramphenicol. Conjunctival swabs for Gram stain should be taken if there is no response to treatment or in suspected gonococccal conjunctivitis (rapid onset of symptoms, copious discharge,
chemosis, and lid oedema). Viral conjunctivitis is usually self-limiting. The patient is highly contagious while the eye is red; strict hygiene and keeping towels separate from other family members is necessary to reduce the chance of transmission.

Fig. 16.3 Anatomy and physiology of the eye.

Sclera- thick protective membrane forming outer coat of eyeball (the white of the eye).

Cornea – transparent dome-shaped anterior portion of outer covering of eye, continuous
with sclera. Provides most of eye’s refractive power.

Conjunctiva – richly vascularized mucous membrane covering anterior surface of sclera and
reflected onto undersurface of upper and lower eyelids. Anterior chamber – contains aqueous humor (produced by ciliary body and drained via canal of Schlemm) providing nutrients and oxygen to cornea.

Iris – coloured part of eye, muscles regulate size of pupil and thus control amount of
light entering eye. Lens – transparent biconvex structure. Changes shape to alter refractive power of the eye. Retina – contains two types of photoreceptors, rods and cones. The cones provide the eye’s colour vision and are mainly confined to the central yellow spot known as the macula. In the centre of that region is the fovea.

Visual loss

Every patient with unexplained visual loss requires ophthalmic referral. The history will determine if the visual loss is transient or persistent. Temporary blurring in one or both eyes or seeing ‘zig-zag’ lines is most commonly due to migraine (p. 774). However, these symptoms can also occur with cerebral vascular lesions or tumours and should not automatically be attributed to migraine unless there is a history of typical migraine headache or the patient is under 50 years and has no other neurological symptoms or signs. Severe temporary visual loss (amaurosis fugax) is due to a transient lack of blood supply to the retina or visual cortex and may occur with a transient ischaemic attack (p. 744) or temporal arteritis (p. 777). Urgent assessment and treat-ment is necessary as amaurosis fugax is a warning sign of impending blind-ness or stroke. Rarely, papilloedema due to raised intracranial pressure can cause transient (lasting seconds) loss of vision in one or both eyes.

All causes of sudden severe visual loss are indications for urgent referral to an ophthalmologist (Table 16.4). Central retinal artery occlusion is an indication for very urgent referral to an ophthalmic centre (within 1 hour).

Table 16.2 Causes of a red eye that do not need urgent referral
  Causes History Acuity/
pupil/
cornea
Site of redness

Conjunctivitis

Bacterial, viral, allergic, chlamydial

Often bilateral. Itchy, gritty eye. Purulent discharge with bacterial iníection

Normal

Diffuse (‘conjunctival’) redness of ocular suríace

Subconjunctival

haemorrhage

Blood between sclera and conjunctiva

May occur after eye rubbing, severe coughing, rarely hypertension or blood clotting disorder

Normal

Diffuse area of bright red blood under conjunctiva of one eye

Episcleritis

Inflammation of episclera (thin
membrane covering sclera)

Mild eye irritation and redness

Normal

Diffuse or localized injection of conjunctiva

Table 16.3 Causes of a red eye requiring urgent (same day) reterral to an ophthalmologist

Causes

History

Visual acuity

Site of redness

Pupil

Cornea

Keratitis (corneal intlammation)

Iníections, autoimmune, exposure keratopathy, contact lens related

Pain, íoreign body sensation, blurred Vision, photophobia

Reduced

Ciliary injection - redness maximal around the edge of the cornea

Normal

Corneal ulceration.
More easily visible with fluorescein
drops and a blue light (Fig. 16.4)

Acute glaucoma

Sudden severe rise in intraocular pressure due to reduced aqueous fluid drainage

Sudden onset of severe eye pain, blurred Vision, rainbow-like ‘haloes’ around lights ± nausea, vomiting

Reduced

Diííuse

Fixed and semi-dilated

Cloudy

Anterior uveitis (iritis)

Autoimmune diseases, sometimes iníectious

Painíul eye, blurred Vision, photophobia

Normal or reduced

Ciliary injection

Small and fixed

Normal

Scleritis

Often underlying vasculitis

Mild to severe eye pain

Normal or decreased

Diffuse or localized

Normal

Normal

Endophthalmitis

Iníection of the eyeball after eye surgery, injury or spread Via the bloodstream

Blurred Vision, painíul eye, photophobia, ‘íloaters’

Decreased

Diffuse or localized

Small and fixed

Cloudy

Fig. 16.5 (A) The fundus in Central retinal vein occlusion compared with (B) the normal appearance of the fundus.

Acute uveitis, acute glaucoma and keratitis present with the combination of a red eye (see above) and sudden or rapidly Progressive visual loss. The initial history and examination of a patient presenting with sudden loss of vision is summarized in Emergency Box 16.1.

Gradual visual loss includes slowly Progressive optic atrophy, chronic glaucoma, cataracts, diabetic retinopathy (p. 681), macular degeneration and chronic retinal detachment. In developing countries trachoma due to Chlamy-dia trachomatis and onchocerciasis (river blindness) due to Onchocerca vol-vulus are also causes of visual loss.

Table 16.4 Causes of sudden or rapidly Progressive visual loss

History

Visual acuity

Pupils

Ophthalmoscopy

Acute retinal detachment

Flashing lights, íloating spots (black or red), field loss (like a curtain Corning in from the periphery)

Usually decreased with a visual field deíect

Pupil in aííected eye dilates in response to light rather than constricting (relative aííerent pupillary deíect, RAPD)

Abnormal red reílex. Detached retina looks grey and wrinkled. Normal examination does not exclude diagnosis

Retinal vein occlusion

Sudden loss of Vision in all (Central vein) or part (branch of retinal vein) of visual field

Decreased, with visual field deíect

RAPD if severe

Retinal haemorrhages, tortuous dilated retinal veins, macular oedema, cotton wool spots (Fig. 16.5)

Retinal artery occlusion

Sudden painless loss of Vision

Markedly reduced

RAPD

Pale retina with Central macular ‘cherry red spot’

Acute optic neuropathy

Rapidly Progressive loss of Vision; may be decreased colour Vision. Symptoms of underlying disease (usually multiple sclerosis or nerve ischaemia due to atherosclerosis)

Decreased

RAPD

Normal or svrollen optic disc

Vitreous

haemorrhage

Severe visual loss if a major bleed, íloating blobs or spots if mild/moderate

Normal or reduced

No RAPD

Decreased red reílex

‘Wet’
age-related
macular
degeneration

Occurs in the elderly. Sudden distortion (straight lines seem curved, Central blank patch of Vision) or blurring of Vision

Decreased acuity with Central scotoma (the macula lies in the centre of the retina and disease causes a Central blank patch on field testing)

Usually no RAPD

Macular oedema (svvelling) and/or subretinal haemorrhages and hard exudates - due to abnormal new vessels under the macula leaking tluid or bleeding

Ebook Essentials of Kumar and Clark's Clinical Medicine, 5e

1. Ethics and communication

Ethics and communication

2. Infectious diseases

Infectious diseases

3. Gastroenterology and nutrition

Gastroenterology and nutrition

4. Liver, biliary tract and pancreatic disease

Liver, biliary tract and pancreatic disease
LIVER BIOCHEMISTRY AND LIVER FUNCTION TESTS
SYMPTOMS AND SIGNS OF LIVER DISEASE
JAUNDICE
HEPATITIS
NON - ALCOHOLIC FATTY LIVER DISEASE (NAFLD)
CIRRHOSIS
COMPLICATIONS AND EFFECTS OF CIRRHOSIS
LIVER TRANSPLANTATION
TYPES OF CHRONIC LIVER DISEASE AND CIRRHOSIS
PRIMARY SCLEROSING CHOLANGITIS
BUDD - CHIARI SYNDROME
LIVER ABSCESS
LIVER DISEASE IN PREGNANCY
LIVER TUMOURS
GALLSTONES
THE PANCREAS
CARCINOMA OF THE PANCREAS
NEUROENDOCRINE TUMOURS OF THE PANCREAS

5. Haematological disease

Haematological disease
ANAEMIA
Assessment and treatment of suspected neutropenic sepsis
HAEMOLYTIC ANAEMIA
INHERITED HAEMOLYTIC ANAEMIAS
ACQUIRED HAEMOLYTIC ANAEMIA
MYELOPROLIFERATIVE DISORDERS
THE SPLEEN
BLOOD TRANSFUSION
THE WHITE CELL
HAEMOSTASIS AND THROMBOSIS
THROMBOSIS
THERAPEUTICS

6. Malignant disease

Malignant disease
MYELOABLATIVE THERAPY AND HAEMOPOIETIC STEM CELL TRANSPLANTATION
THE LYMPHOMAS
THE PARAPROTEINAEMIAS
PALLIATIVE MEDICINE AND SYMPTOM CONTROL

7. Rheumatology

Rheumatology
COMMON INVESTIGATIONS IN MUSCULOSKELETAL DISEASE
COMMON REGIONAL MUSCULOSKELETAL PROBLEMS
BACK PAIN
OSTEOARTHRITIS
INFLAMMATORY ARTHRITIS
THE SERONEGATIVE SPONDYLOARTHROPATHIES
Clinical features, Investigations
INFECTION OF JOINTS AND BONES
AUTOIMMUNE RHEUMATIC DISEASES
SYSTEMIC INFLAMMATORY VASCULITIS
DISEASES OF BONE
THERAPEUTICS

8. Water, electrolytes and acid–base balance

WATER AND ELECTROLYTE REQUIREMENTS
BODY FLUID COMPARTMENTS
REGULATION OF BODY FLUID HOMEOSTASIS
PLASMA OSMOLALITY AND DISORDERS OF SODIUM REGULATION
DISORDERS OF POTASSIUM REGULATION
DISORDERS OF MAGNESIUM REGULATION
DISORDERS OF ACID - BASE BALANCE
THERAPEUTICS

9. Renal disease

Renal disease
INVESTIGATION OF RENAL DISEASE
GLOMERULAR DISEASES
NEPHROTIC SYNDROME
URINARY TRACT INFECTION
TUBULOINTERSTITIAL NEPHRITIS
HYPERTENSION AND THE KIDNEY
RENAL CALCULI AND NEPHROCALCINOSIS
URINARY TRACT OBSTRUCTION
ACUTE RENAL FAILURE/ACUTE KIDNEY INJURY
CHRONIC KIDNEY DISEASE
RENAL REPLACEMENT THERAPY
CYSTIC RENAL DISEASE
TUMOURS OF THE KIDNEY AND GENITOURINARY TRACT
DISEASES OF THE PROSTATE GLAND
TESTICULAR TUMOUR
URINARY INCONTINENCE

10. Cardiovascular disease

COMMON PRESENTING SYMPTOMS OF HEART DISEASE
INVESTIGATIONS IN CARDIAC DISEASE
CARDIAC ARRHYTHMIAS
HEART FAILURE
ISCHAEMIC HEART DISEASE
RHEUMATIC FEVER
VALVULAR HEART DISEASE
PULMONARY HEART DISEASE
MYOCARDIAL DISEASE
CARDIOMYOPATHY
PERICARDIAL DISEASE
SYSTEMIC HYPERTENSION
ARTERIAL AND VENOUS DISEASE
ELECTRICAL CARDIOVERSION
DRUGS FOR ARRHYTHMIAS
DRUGS FOR HEART FAILURE
DRUGS AFFECTING THE RENIN - ANGIOTENSIN SYSTEM
NITRATES, CALCIUM - CHANNEL BLOCKERS AND POTASSIUM - CHANNEL ACTIVATORS

11. Respiratory disease


Respiratory disease
TUBERCULOSISnd
DIFFUSE DISEASES OF THE LUNG PARENCHYMA
OCCUPATIONAL LUNG DISEASE
CARCINOMA OF THE LUNG
DISEASES OF THE CHEST WALL AND PLEURA
DISORDERS OF THE DIAPHRAGM

12. Intensive care medicine

Intensive care medicine

13. Drug therapy, poisoning, and alcohol misuse

Drug therapy, poisoning, and alcohol misuse

14. Endocrine disease

Endocrine disease
PITUITARY HYPERSECRETION SYNDROMES
THE THYROID AXIS
MALE REPRODUCTION AND SEX
FEMALE REPRODUCTION AND SEX
THE GLUCOCORTICOID AXIS
THE THIRST AXIS
DISORDERS OF CALCIUM METABOLISM
DISORDERS OF PHOSPHATE CONCENTRATION
ENDOCRINOLOGY OF BLOOD PRESSURE CONTROL
DISORDERS OF TEMPERATURE REGULATION
THERAPEUTICS

15. Diabetes mellitus and other disorders of metabolism

DIABETES MELLITUS
DIABETIC METABOLIC EMERGENCIES
COMPLICATIONS OF DIABETES
SPECIAL SITUATIONS
HYPOGLYCAEMIA IN THE NON - DIABETIC
DISORDERS OF LIPID METABOLISM
THE PORPHYRIAS

16. The special senses

THE EAR
THE NOSE AND NASAL CAVITY
THE THROAT
THE EYE

17. Neurology

COMMON NEUROLOGICAL SYMPTOMS
COORDINATION OF MOVEMENT
THE CRANIAL NERVES
COMMON INVESTIGATIONS IN NEUROLOGICAL DISEASE
UNCONSCIOUSNESS AND COMA
STROKE AND CEREBROVASCULAR DISEASE
EPILEPSY AND LOSS OF CONSCIOUSNESS
NERVOUS SYSTEM INFECTION AND INFLAMMATION
HYDROCEPHALUS
HEADACHE, MIGRAINE AND FACIAL PAIN
SPINAL CORD DISEASE
DEGENERATIVE NEURONAL DISEASES
DISEASES OF THE PERIPHERAL NERVES
MUSCLE DISEASES
MYOTONIAS
DELIRIUM
THERAPEUTICS

18. Dermatology

Dermatology



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