Ophthalmology Flashcards
Glaucoma
Glaucoma refers to the optic nerve damage that is caused by a significant rise in intraocular pressure. The raised intraocular pressure is caused by a blockage in aqueous humour trying to escape the eye. There are two types of glaucoma: open-angle and closed-angle.
Basic anatomy and physiology of the eye
The vitreous chamber of the eye is filled with vitreous humour.
The anterior chamber between the cornea and the iris and the posterior chamber between the lens and the iris are filled with aqueous humour that supplies nutrients to the cornea.
The aqueous humour is produced by the ciliary body. The aqueous humour flows from the ciliary body, around the lens and under the iris, through the anterior chamber, through the trabecular meshwork and into the canal of Schlemm. From the canal of Schlemm it eventually enters the general circulation.
The normal intraocular pressure is 10-21 mmHg. This pressure is created by the resistance to flow through the trabecular meshwork into the canal of Schlemm.
Pathophysiology of open-angle glaucoma
In open-angle glaucoma, there is a gradual increase in resistance through the trabecular meshwork. This makes it more difficult for aqueous humour to flow through the meshwork and exit the eye. Therefore the pressure slowly builds within the eye and this gives a slow and chronic onset of glaucoma.
In acute angle-closure glaucoma, the iris bulges forward and seals off the trabecular meshwork from the anterior chamber preventing aqueous humour from being able to drain away. This leads to a continual build-up of pressure. This is an ophthalmology emergency.
Increased pressure in the eye causes cupping of the optic disc. In the centre of a normal optic disc is the optic cup. This is a small indent in the optic disc. It is usually less than half the size of the optic disc. When there is raised intraocular pressure, this indent becomes larger as the pressure in the eye puts pressure on that indent making it wider and deeper. This is called “cupping”. An optic cup greater than 0.5 the size of the optic disc is abnormal.
Risk factors for open-angle glaucoma
Increasing age
Family history
Black ethnic origin
Nearsightedness (myopia)
Presentation of open-angle glaucoma
Often the rise in intraocular pressure is asymptomatic for a long period of time. It is diagnosed by routine screening when attending optometry for an eye check.
Glaucoma affects peripheral vision first. Gradually the peripheral vision closes in until they experience tunnel vision.
It can present with gradual onset of fluctuating pain, headaches, blurred vision and halos appearing around lights, particularly at night time.
Measuring intraocular pressure
Non-contact tonometry is the commonly used machine for estimating intraocular pressure by opticians. It involves shooting a “puff of air” at the cornea and measuring the corneal response to that air. It is less accurate but gives a helpful estimate for general screening purposes.
Goldmann applanation tonometry is the gold standard way to measure intraocular pressure. This involves a special device mounted on a slip lamp that makes contact with the cornea and applies different pressures to the front of the cornea to get an accurate measurement of what the intraocular pressure is.
Diagnosing open-angle glaucoma
Goldmann applanation tonometry can be used to check the intraocular pressure.
Fundoscopy assessment to check for optic disc cupping and optic nerve health.
Visual field assessment to check for peripheral vision loss.
Managing open-angle glaucoma
Management of glaucoma aims to reduce the intraocular pressure. Treatment is usually started at an intraocular pressure of 24 mmHg or above. Patients are followed up closely to assess the response to treatment.
Prostaglandin analogue eye drops (e.g. latanoprost) are first line. These increase uveoscleral outflow. Notable side effects are eyelash growth, eyelid pigmentation and iris pigmentation (browning).
Other options:
Beta-blockers (e.g. timolol) reduce the production of aqueous humour
Carbonic anhydrase inhibitors (e.g. dorzolamide) reduce the production of aqueous humour
Sympathomimetics (e.g. brimonidine) reduce the production of aqueous fluid and increase uveoscleral outflow
Trabeculectomy surgery may be required where eye drops are ineffective. This involves creating a new channel from the anterior chamber, through the sclera to a location under the conjunctiva. It causes a “bleb” under the conjunctiva where the aqueous humour drains. It is then reabsorbed from this bleb into the general circulation.
Acute angle-closure glaucoma
Glaucoma refers to the optic nerve damage that is caused by a significant rise in intraocular pressure. The raised intraocular pressure is caused by a blockage in aqueous humour trying to escape the eye.
Acute angle-closure glaucoma occurs when the iris bulges forward and seals off the trabecular meshwork from the anterior chamber preventing aqueous humour from being able to drain away. This leads to a continual build-up of pressure in the eye. The pressure builds up particularly in the posterior chamber, which causes pressure behind the iris and worsens the closure of the angle.
Acute angle-closure glaucoma is an ophthalmology emergency. Emergency treatment is required to prevent permanent loss of vision.
Risk factors for acute angle-closure glaucoma
The risk factors are slightly different to open-angle glaucoma:
Increasing age
Females are affected around 4 times more often than males
Family history
Chinese and East Asian ethnic origin. Unlike open-angle glaucoma, it is rare in people of black ethnic origin.
Shallow anterior chamber
Certain medications can precipitate acute angle-closure glaucoma:
Adrenergic medications such as noradrenalin
Anticholinergic medications such as oxybutynin and solifenacin
Tricyclic antidepressants such as amitriptyline, which have anticholinergic effects
Presentation of acute angle-closure glaucoma
The patient will generally appear unwell in themselves. They have a short history of:
Severely painful red eye
Blurred vision
Halos around lights
Associated headache, nausea and vomiting
Examination of acute angle-closure glaucoma
Red-eye
Teary
Hazy cornea
Decreased visual acuity
Dilatation of the affected pupil
Fixed pupil size
Firm eyeball on palpation
Initial management of acute angle-closure glaucoma
NICE CKS 2019 say patients with potentially life-threatening causes of red eye should be referred for same-day assessment by an ophthalmologist. If there is a delay in admission, whilst waiting for an ambulance:
Lie patient on their back without a pillow
Give pilocarpine eye drops (2% for blue, 4% for brown eyes)
Give acetazolamide 500 mg orally
Given analgesia and an antiemetic if required
Pilocarpine acts on the muscarinic receptors in the sphincter muscles in the iris and causes constriction of the pupil. Therefore it is a miotic agent. It also causes ciliary muscle contraction. These two effects cause the pathway for the flow of aqueous humour from the ciliary body, around the iris and into the trabecular meshwork to open up.
Acetazolamide is a carbonic anhydrase inhibitor. This reduces the production of aqueous humour.
Secondary care management of acute angle-closure glaucoma
Various medical options can be tried to reduce the pressure:
Pilocarpine
Acetazolamide (oral or IV)
Hyperosmotic agents such as glycerol or mannitol increase the osmotic gradient between the blood and the fluid in the eye
Timolol is a beta-blocker that reduces the production of aqueous humour
Dorzolamide is a carbonic anhydrase inhibitor that reduces the production of aqueous humour
Brimonidine is a sympathomimetic that reduces the production of aqueous fluid and increase uveoscleral outflow
Laser iridotomy is usually required as a definitive treatment. This involves using a laser to make a hole in the iris to allow the aqueous humour to flow from the posterior chamber into the anterior chamber. This relieves pressure that was pushing the iris against the cornea and allows the humour the drain.
Age related macular degeneration
Age-related macular degeneration is a condition where there is degeneration in the macula that cause a progressive deterioration in vision. In the UK it is the most common cause of blindness. A key finding associated with macular degeneration is drusen seen during fundoscopy.
There are two types, wet and dry. 90% of cases are dry and 10% are wet. Wet age-related macular degeneration carries a worse prognosis.
The macula is made of four key layers. At the bottom, there is the choroid layer, which contains blood vessels that provide the blood supply to the macula. Above that is Bruch’s membrane. Above Bruch’s membrane there is the retinal pigment epithelium and above that are the photoreceptors.
Drusen are yellow deposits of proteins and lipids that appear between the retinal pigment epithelium and Bruch’s membrane. Some drusen can be normal. Normal drusen are small (< 63 micrometres) and hard. Larger and greater numbers of drusen can be an early sign of macular degeneration. They are common to both wet and dry AMD.
Other features that are common to wet and dry AMD are:
Atrophy of the retinal pigment epithelium
Degeneration of the photoreceptors
In wet AMD there is the development of new vessels growing from the choroid layer into the retina. These vessels can leak fluid or blood and cause oedema and more rapid loss of vision. A key chemical that stimulates the development of new vessels is vascular endothelial growth factor (VEGF) and this is the target of medications to treat wet AMD.
Risk factors for age related macular degeneration
Age
Smoking
White or Chinese ethnic origin
Family history
Cardiovascular disease
Presentation of age related macular degeneration
There are some key visual changes to remember for spotting AMD in your exams:
Gradual worsening central visual field loss
Reduced visual acuity
Crooked or wavy appearance to straight lines
Wet age-related macular degeneration presents more acutely. It can present with a loss of vision over days and progress to full loss of vision over 2-3 years. It often progresses to bilateral disease.
Examining age related macular degeneration
Reduced acuity using a Snellen chart
Scotoma (a central patch of vision loss)
Amsler grid test can be used to assess the distortion of straight lines
Fundoscopy. Drusen are the key finding.
Slit-lamp biomicroscopic fundus examination by a specialist can be used to diagnose AMD.
Optical coherence tomography is a technique used to gain a cross-sectional view of the layers of the retina. It can be used to diagnose wet AMD.
Fluorescein angiography involves giving a fluorescein contrast and photographing the retina to look in detail at the blood supply to the retina. It is useful to show up any oedema and neovascularisation. It is used second line to diagnose wet AMD if optical coherence tomography does not exclude wet AMD.
Managing dry AMD
There is no specific treatment for dry age-related macular degeneration. Management focuses on lifestyle measure that may slow the progression:
Avoid smoking
Control blood pressure
Vitamin supplementation has some evidence in slowing progression
Managing wet AMD
Anti-VEGF medications are used to treat wet age-related macular degeneration. Vascular endothelial growth factor is involved in the development of new blood vessels in the retina. Medications such as ranibizumab, bevacizumab and pegaptanib block VEGF and slow the development of new vessels. They are injected directly into the vitreous chamber of the eye once a month. They slow and even reverse the progression of the disease. They typically need to be started within 3 months to be beneficial.
Diabetic retinopathy
Diabetic retinopathy is a condition where the blood vessels in the retina are damaged by prolonged exposure to high blood sugar levels (hyperglycaemia) causing a progressive deterioration in the health of the retina.
Pathophysiology of diabetic retinopathy
Hyperglycaemia leads to damage to the retinal small vessels and endothelial cells. Increased vascular permeability leads to leakage from the blood vessels, blot haemorrhages and the formation of hard exudates. Hard exudates are yellow/white deposits of lipids in the retina.
Damage to the blood vessel walls leads to microaneurysms and venous beading. Microaneurysms are where weakness in the wall causes small bulges. Venous beading is where the walls of the veins are no longer straight and parallel and look more like a string of beads or sausages.
Damage to nerve fibres in the retina causes fluffy white patches to form on the retina called cotton wool spots.
Intraretinal microvascular abnormalities (IMRA) is where there are dilated and tortuous capillaries in the retina. These can act as a shunt between the arterial and venous vessels in the retina.
Neovascularisation is when growth factors are released in the retina causing the development of new blood vessels.
Classification of diabetic retinopathy
Diabetic retinopathy can be split into two broad categories: non-proliferative and proliferative depending on whether new blood vessels have developed. Non-proliferative is often called background or pre-proliferative retinopathy as it can develop in to proliferative retinopathy. A condition called diabetic maculopathy also exists separate from non-proliferative and proliferative diabetic retinopathy.
These conditions are classified based on the findings on fundus examination.
Non-proliferative diabetic retinopathy
Mild: microaneurysms
Moderate: microaneurysms, blot haemorhages, hard exudates, cotton wool spots and venous beading
Severe: blot haemorrhages plus microaneurysms in 4 quadrants, venous beading in 2 quadrates, intraretinal microvascular abnormality (IMRA) in any quadrant
Proliferative diabetic retinopathy
Neovascularisation
Vitreous haemorrhage
Diabetic maculopathy
Macular oedema
Ischaemic maculopathy
Complications of diabetic retinopathy
Retinal detachment
Vitreous haemorrhage (bleeding in to the vitreous humour)
Rebeosis iridis (new blood vessel formation in the iris)
Optic neuropathy
Cataracts
Managing diabetic retinopathy
Laser photocoagulation
Anti-VEGF medications such as ranibizumab and bevacizumab
Vitreoretinal surgery (keyhole surgery on the eye) may be required in severe disease
Hypertensive retinopathy
Hypertensive retinopathy describes the damage to the small blood vessels in the retina relating to systemic hypertension. This can be the result of years of chronic hypertension or can develop quickly in response to malignant hypertension. There are a number of signs that occur within the retina in response to the effects of hypertension in these vessels.
Silver wiring or copper wiring is where the walls of the arterioles become thickened and sclerosed causing increased reflection of the light.
Arteriovenous nipping is where the arterioles cause compression of the veins where they cross. This is again due to sclerosis and hardening of the arterioles.
Cotton wool spots are caused by ischaemia and infarction in the retina causing damage to nerve fibres.
Hard exudates are caused by damaged vessels leaking lipids into the retina.
Retinal haemorrhages are caused by damaged vessels rupturing and releasing blood into the retina.
Papilloedema is caused by ischaemia to the optic nerve resulting in optic nerve swelling (oedema) and blurring of the disc margins.
Keith-Wagener classification
Stage 1: Mild narrowing of the arterioles
Stage 2: Focal constriction of blood vessels and AV nicking
Stage 3: Cotton-wool patches, exudates and haemorrhages
Stage 4: Papilloedema
Managing hypertensive retinopathy
Management is focused on controlling the blood pressure and other risk factors such as smoking and blood lipid levels.
Cataracts
Cataracts are where the lens in the eye becomes cloudy and opaque. This reduces visual acuity by reducing the light that enters the eye.
The job of the lens is to focus light coming into the eye onto the retina at the back of the eye. It is held in place by suspensory ligaments attached to the ciliary body. The ciliary body contracts and relaxes to focus the lens. When the ciliary body contracts it releases tension on the suspensory ligaments and the lens thickens. When the ciliary body relaxes it increases the tension in the suspensory ligaments and the lens narrows. The lens is nourished by the surrounding fluid and doesn’t have a blood supply. It grows and develops throughout life.
Most cataracts develop over years with advanced age in the presence of risk factors. Congenital cataracts occur before birth and are screened for using the red reflex during the neonatal examination.
Risk factors for cataracts
Increasing age
Smoking
Alcohol
Diabetes
Steroids
Hypocalcaemia
Presentation of cataracts
Symptoms are usually asymmetrical as both eyes are affected separately. It presents with:
Very slow reduction in vision
Progressive blurring of vision
Change of colour of vision with colours becoming more brown or yellow
“Starbursts” can appear around lights, particularly at night time
A key sign for cataracts is the loss of the red reflex. The lens can appear grey or white when testing the red reflex. This might show up on photographs taken with a flash.
TOM TIP: It is useful in exams to distinguish the causes of visual problems based on the symptoms. Cataracts cause a generalised reduction in visual acuity with starbursts around lights. Glaucoma causes a peripheral loss of vision with halos around lights. Macular degeneration causes a central loss of vision with a crooked or wavy appearance to straight lines.
Managing cataracts
If the symptoms are manageable then no intervention may be necessary.
Cataract surgery involves drilling and breaking the lens into pieces, removing the pieces and then implanting an artificial lens into the eye. This is usually done as a day case under local anaesthetic. It usually gives good results.
It is worth noting that cataracts can prevent the detection of other pathology such as macular degeneration or diabetic retinopathy. Once cataract surgery is performed these conditions may be detected. Therefore, the surgery may treat the cataract but they may still have poor visual acuity due to other causes.
Endophthalmitis
Endophthalmitis is a rare but serious complication of cataract surgery. It is inflammation of the inner contents of the eye, usually caused by infection. It can be treated with intravitreal antibiotics injected into the eye. This can lead to loss of vision and loss of the eye itself.
Pupil constriction
There are circular muscles in the iris that cause pupil constriction. They are stimulated by the parasympathetic nervous system using acetylcholine as a neurotransmitter. The fibres of the parasympathetic system innervating the eye travel along the oculomotor (third cranial) nerve.
Pupil dilation
The dilator muscles of the pupil arranged like spokes on a bicycle wheel travelling straight from the inside to the outside of the iris. They are stimulated by the sympathetic nervous system using adrenalin as a neurotransmitter.
Abnormal pupil shape
Trauma to the sphincter muscles in the iris can cause an irregular pupil. This could be caused by cataract surgery and other eye operations.
Anterior uveitis can cause adhesions (scar tissue) in the iris that make the pupils misshapen.
Acute angle closure glaucoma can cause ischaemic damage to the muscles of the iris causing an abnormal pupil shape, usually a vertical oval.
Rubeosis iridis (neovascularisation in the iris) can distort the shape of the iris and pupil. This is usually associated with poorly controlled diabetes and diabetic retinopathy.
Coloboma is a congenital malformation in the eye. This can cause a hole in the iris causing an irregular pupil shape.
Tadpole pupil is where there is spasm in a segment of the iris causing a misshapen pupil. This is usually temporary and associated with migraines.
Causes of mydriasis (dilated pupil)
Third nerve palsy
Holmes-Adie syndrome
Raised intracranial pressure
Congenital
Trauma
Stimulants such as cocaine
Anticholinergics
Causes of miosis (constricted pupil)
Horners syndrome
Cluster headaches
Argyll-Robertson pupil (in neurosyphilis)
Opiates
Nicotine
Pilocarpine
Third nerve palsy
A third nerve palsy causes:
Ptosis (drooping upper eyelid)
Dilated non-reactive pupil
Divergent strabismus (squint) in the affected eye. It causes a “down and out” position of the eye.
The third cranial nerve is the oculomotor nerve. It supplies all of the extraocular muscles except the lateral rectus and superior oblique. Therefore when these muscles are no longer getting signals from the oculomotor nerve, the eyes moves outward and downward due to the effects of the lateral rectus and superior oblique still functioning without resistance.
It also supplies the levator palpebrae superioris, which is responsible for lifting the upper eyelid. Therefore third nerve palsy causes a ptosis.
The oculomotor nerve also contains parasympathetic fibres that innervate the sphincter muscle of the iris. Therefore third nerve palsy causes a dilated fixed pupil.
The oculomotor nerve travels directly from the brainstem to the eye in a straight line. It travels through the cavernous sinus and close to the posterior communicating artery. Therefore, cavernous sinus thrombosis and a posterior communicating artery aneurysm can cause compression of the nerve and a third nerve palsy.
Causes of a third nerve palsy
Third nerve palsy can be idiopathic, without a clear cause.
A third nerve palsy with sparing of the pupil suggests a microvascular cause as the parasympathetic fibres are spared. This may be due to:
Diabetes
Hypertension
Ischaemia
A full third nerve palsy is caused by compression of the nerve, including the parasympathetic fibres. This is called a “surgical third” due to the physical compression:
Idiopathic
Tumour
Trauma
Cavernous sinus thrombosis
Posterior communicating artery aneurysm
Raised intracranial pressure
Horner syndrome
Horner syndrome is a triad of:
Ptosis
Miosis
Anhidrosis (loss of sweating)
They may also have enopthalmos, which is a sunken eye. Light and accommodation reflexes are not affected.
Horner syndrome is caused by damage to the sympathetic nervous system supplying the face.
The journey of the sympathetic nerves to the head is relevant for the causes of Horner syndrome. The sympathetic nerves arise from the spinal cord in the chest. These are pre-ganglionic nerves. They then enter into the sympathetic ganglion at the base of the neck and exit as post-ganglionic nerves. These post-ganglionic nerves then travel to the head, running alongside the internal carotid artery.
The location of the Horner syndrome can be determined by the anhidrosis. Central lesions cause anhidrosis of the arm and trunk as well as the face. Pre-ganglionic lesions cause anhidrosis of the face. Post-ganglionic lesions do not cause anhidrosis.
Causes of Horner syndrome
The causes can be remembered as the 4 Ss, 4 Ts and 4 Cs. S for Sentral, T for Torso (pre-ganglionic) and C for Cervical (post-ganglionic).
Central lesions (4 Ss):
S – Stroke
S – Multiple Sclerosis
S – Swelling (tumours)
S – Syringomyelia (cyst in the spinal cord)
Pre-ganglionic lesions (4 Ts):
T – Tumour (Pancoast’s tumour)
T – Trauma
T – Thyroidectomy
T – Top rib (a cervical rib growing above the first rib above the clavicle)
Post-ganglionic lesion (4 Cs):
C – Carotid aneurysm
C – Carotid artery dissection
C – Cavernous sinus thrombosis
C – Cluster headache
Testing Horner syndrome
Congenital Horner syndrome is associated with heterochromia, which is a difference in the colour of the iris on the affected side.
Cocaine eye drops can be used to test for Horner syndrome. Cocaine acts on the eye to stop noradrenalin re-uptake at the neuromuscular junction. This causes a normal eye to dilate because there is more noradrenalin stimulating the dilator muscles of the iris. In Horner syndrome, the nerves are not releasing noradrenalin to start with so blocking re-uptake does not make a difference and there is no reaction of the pupil.
Alternatively, a low concentration adrenalin eye drop (0.1%) won’t dilate a normal pupil but will dilate a Horner syndrome pupil.
Holmes Adie Pupil
A Holmes Adie pupil is a unilateral dilated pupil that is sluggish to react to light with slow dilation of the pupil following constriction. Over time the pupil will get smaller. This is caused by damage to the post-ganglionic parasympathetic fibres. The exact cause is unknown but may be viral.
Holmes Adie Syndrome is where there is a Holmes Adie pupil with absent ankle and knee reflexes.
Argyll-Robertson Pupil
An Argyll-Robertson pupil is a specific finding in neurosyphilis. It is a constricted pupil that accommodates when focusing on a near object but does not react to light. They are often irregularly shaped. It is commonly called “prostitutes pupil” due to the relation to neurosyphilis and because “it accommodates but does not react“.
Blepharitis
Blepharitis is inflammation of the eyelid margins.
It causes a gritty, itchy, dry sensation in the eyes. It can be associated with dysfunction of the Meibomian glands, which are responsible for secreting oil onto the surface of the eye. It can lead to styes and chalazions.
Managing blepharitis
Management is with hot compresses and gentle cleaning of the eyelid margins to remove debris using cotton wool dipped in sterilised water and baby shampoo.
Lubricating eye drops can be used to relieve symptoms:
Hypromellose is the least viscous. The effect lasts around 10 minutes.
Polyvinyl alcohol is the middle viscous choice. It is worth starting with these.
Carbomer is the most viscous and lasts 30 – 60 minutes.
Stye
Hordeolum externum is an infection of the glands of Zeis or glands of Moll. The glands of Moll are sweat glands at the base of the eyelashes. The glands of Zeis are sebaceous glands at the base of the eyelashes. A stye causes a tender red lump along the eyelid that may contain pus.
Hordeolum internum is infection of the Meibomian glands. They are deeper, tend to be more painful and may point inwards towards the eyeball underneath the eyelid.
Managing styes
Styes are treated with hot compresses and analgesia. Consider topic antibiotics (i.e. chloramphenicol) if it is associated with conjunctivitis or persistent.
Chalazion
A chalazion occurs when a Meibomian gland becomes blocked and swells up. It is often called a Meibomian cyst. It presents with a swelling in the eyelid that is typically not tender. It can be tender and red.
Managing chalazions
Treatment is with hot compress and analgesia. Consider topic antibiotics (i.e. chloramphenicol) if acutely inflamed.
Rarely if conservative management fails then surgical drainage may be required.
Entropion
Entropion is where the eyelid turns inwards with the lashes against the eyeball.
This results in pain and can result in corneal damage and ulceration.
Managing entropions
Initial management is by taping the eyelid down to prevent it turning inwards. Definitive management is with surgical intervention. When the eyelid is taped down it is essential to prevent the eye drying out by using regular lubricating eye drops.
A same-day referral to ophthalmology is required if there is a risk to sight.
Ectropion
Ectropion is where the eyelid turns outwards with the inner aspect of the eyelid exposed. It usually affects the bottom lid.
This can result in exposure keratopathy as the eyeball is exposed and not adequately lubricated and protected.
Managing ectropions
Mild cases may not require treatment. Regular lubricating eye drops are used to protect the surface of the eye. More significant cases may require surgery to correct the defect.
A same-day referral to ophthalmology is required if there is a risk to sight.
Trichiasis
Trichiasis is inward growth of the eyelashes. This results in pain and can result in corneal damage and ulceration.
Managing trichiasis
Management by a specialist is to remove the eyelash (epilation). Recurrent cases may require electrolysis, cryotherapy or laser treatment to prevent the lash regrowing.
A same day referral to ophthalmology is required if there is a risk to sight.
Periorbital cellulitis
Periorbital cellulitis (also known as preorbital cellulitis) is an eyelid and skin infection in front of the orbital septum (in front of the eye). It presents with swelling, redness and hot skin around the eyelids and eye.
It is essential to differentiate it from orbital cellulitis, which is a sight and life threatening emergency. CT scan can help distinguish between the two.
Treating periorbital cellulitis
Treatment is with systemic antibiotics (oral or IV). Preorbital cellulitis can develop into orbital cellulitis so vulnerable patients (e.g. children) or severe cases may require admission for observation while they are treated.
Orbital cellulitis
Orbital cellulitis is an infection around the eyeball that involves tissues behind the orbital septum.
Key features that differential this from periorbital celluitis is pain on eye movement, reduced eye movements, changes in vision, abnormal pupil reactions and forward movement of the eyeball (proptosis).
Treating orbital cellulitis
This is a medical emergency that requires admission and IV antibiotics. They may require surgical drainage if an abscess forms.
Conjunctivitis
Conjunctivitis is inflammation of the conjunctiva. The conjunctiva is a thin layer of tissue that covers the inside of the eyelids and the sclera of the eye. There are three main types:
Bacterial
Viral
Allergic
Presentation of conjunctivitis
Conjunctivitis presents with:
Unilateral or bilateral
Red eyes
Bloodshot
Itchy or gritty sensation
Discharge from the eye
Conjunctivitis does not cause pain, photophobia or reduced visual acuity. Vision may be blurry when the eye is covered with discharge, however when the discharge is cleared the acuity should be normal.
Bacterial conjunctivitis presents with a purulent discharge and an inflamed conjunctiva. It is typically worse in the morning when the eyes may be stuck together. It usually starts in one eye and then can spread to the other. It is highly contagious.
Viral conjunctivitis is common and usually presents with a clear discharge. It is often associated with other symptoms of a viral infection such as dry cough, sore throat and blocked nose. You may find tender preauricular lymph nodes (in front of the ears). It is also contagious.
Painless red eye
Conjunctivitis
Episcleritis
Subconjunctival Haemorrhage
Painful red eye
Glaucoma
Anterior uveitis
Scleritis
Corneal abrasions or ulceration
Keratitis
Foreign body
Traumatic or chemical injury
The more serious differentials tend to cause pain and reduced visual acuity.
Managing conjunctivitis
Conjunctivitis usually resolves without treatment after 1-2 weeks.
Advise on good hygiene to avoid spreading (e.g. avoid sharing towels or rubbing eyes and regularly washing hands) and avoiding the use of contact lenses. Cleaning the eyes with cooled boiled water and cotton wool can help clear the discharge.
If bacterial conjunctivitis is suspected then antibiotic eye drops can be considered, however bear in mind it will often get better without treatment. Chloramphenicol and fuscidic acid eye drops are both options.
Patients under the age of 1 month of age with conjunctivitis need urgent ophthalmology review as neonatal conjunctivitis can be associated gonococcal infection and can cause loss of sight and more severe complications such as pneumonia.
Allergic conjunctivitis
Allergic conjunctivitis is caused by contact with allergens. It causes swelling of the conjunctival sac and eye lid with a significant watery discharge and itch.
Antihistamines (oral or topical) can be used to reduce symptoms.
Topical mast-cell stabilisers can be used in patients with chronic seasonal symptoms. They work by preventing mast cells releasing histamine. These require use for several weeks before showing any benefit.
Anterior uveitis
Anterior uveitis is inflammation in the anterior part of the uvea. The uvea involves the iris, ciliary body and choroid. The choroid is the layer between the retina and the sclera all the way around the eye. Sometimes anterior uveitis is referred to as iritis.
It involves inflammation and immune cells in the anterior chamber of the eye. The anterior chamber of the eye becomes infiltrated by neutrophils, lymphocytes and macrophages. This is usually caused by an autoimmune process but can be due to infection, trauma, ischaemia or malignancy. Inflammatory cells in the anterior chamber cause floaters in the patient’s vision.
Anterior uveitis can be acute or chronic. Chronic anterior uveitis is more granulomatous (has more macrophages) and has a less severe and longer duration of symptoms, lasting more than 3 months.
Associations of acute anterior uveitis
Acute anterior uveitis is associated with HLA B27 related conditions:
Ankylosing spondylitis
Inflammatory bowel disease
Reactive arthritis
Associations of chronic anterior uveitis
Chronic anterior uveitis is associated with:
Sarcoidosis
Syphilis
Lyme disease
Tuberculosis
Herpes virus
Presentation of anterior uveitis
Anterior uveitis usually presents with unilateral symptoms that start spontaneously without a history of trauma or precipitating events. They may occur with a flare of an associated disease such as reactive arthritis.
Symptoms include:
Dull, aching, painful red eye
Ciliary flush (a ring of red spreading from the cornea outwards)
Reduced visual acuity
Floaters and flashes
Sphincter muscle contraction causing miosis (constricted pupil)
Photophobia due to ciliary muscle spasm
Pain on movement
Excessive tear production (lacrimation)
Abnormally shaped pupil due to posterior synechiae (adhesions) pulling the iris into abnormal shapes
A hypopyon is a collection of white blood cells in the anterior chamber, seen as a yellowish fluid collection settled in front of the lower iris, with a fluid level
Managing anterior uveitis
NICE Clinical Knowledge Summaries on red eye say patients with potentially sight threatening causes of red eye should be referred for same day assessment by an ophthalmologist. They need full slit lamp assessment of the different structures of the eye and intraocular pressures to establish the diagnosis.
The ophthalmologist will guide treatment choices:
Steroids (oral, topical or intravenous)
Cycloplegic-mydriatic medications such as cyclopentolate or atropine eye drops. Cycloplegic means paralysing the ciliary muscles. Mydriatic means dilating the pupils. Cyclopentolate and atropine are antimuscarinic medications that blocks to the action of the iris sphincter muscles and ciliary body. These dilate the pupil and reduce pain associated with ciliary spasm by stopping the action of the ciliary body.
Immunosuppressants such as DMARDS and TNF inhibitors
Laser therapy, cryotherapy or surgery (vitrectomy) are also options in severe cases.
Episcleritis
Episcleritis is benign and self-limiting inflammation of the episclera, the outermost layer of the sclera. The episclera is situated just underneath the conjunctiva.
It is relatively common in young and middle-aged adults and is not usually caused by infection. It is often associated with inflammatory disorders such as rheumatoid arthritis and inflammatory bowel disease.
Presentation of episcleritis
Episcleritis usually presents with acute onset unilateral symptoms:
Typically not painful but there can be mild pain
Segmental redness (rather than diffuse). There is usually a patch of redness in the lateral sclera.
Foreign body sensation
Dilated episcleral vessels
Watering of eye
No discharge
Managing episcleritis
If in doubt about the diagnosis, refer to ophthalmology.
Episcleritis is usually self limiting and will recover in 1-4 weeks. In mild cases no treatment is necessary. Lubricating eye drops can help symptoms.
Simple analgesia, cold compresses and safetynet advice are appropriate.
More severe cases may benefit from systemic NSAIDs (e.g. naproxen) or topical steroid eye drops.
Scleritis
Scleritis involves inflammation of the full thickness of the sclera. This is more serious than episcleritis. It is not usually caused by infection.
The most severe type of scleritis is called necrotising scleritis. Most patients with necrotising scleritis have visual impairment but may not have pain. It can lead to perforation of the sclera. This is the most significant complication of scleritis.
Associated systemic conditions of scleritis
There is an associated systemic condition in around 50% of patients presenting with scleritis. This may be:
Rheumatoid arthritis
Systemic lupus erythematosus
Inflammatory bowel disease
Sarcoidosis
Granulomatosis with polyangiitis
Presentation of scleritis
Scleritis usually presents with an acute onset of symptoms. Around 50% of cases are bilateral.
Severe pain
Pain with eye movement
Photophobia
Eye watering
Reduced visual acuity
Abnormal pupil reaction to light
Tenderness to palpation of the eye
Managing scleritis
NICE Clinical Knowledge Summaries on red eye say patients with potentially sight threatening causes of red eye should be referred for same day assessment by an ophthalmologist.
Management in secondary care involves:
Consider an underlying systemic condition
NSAIDS (topical/ systemic)
Steroids (topical/ systemic)
Immunosuppression appropriate to the underlying systemic condition (e.g. methotrexate in rheumatoid arthritis)
Corneal abrasions
Corneal abrasions are scratches or damage to the cornea. They are a cause of red, painful eye. There are some common causes:
Contact lenses
Foreign bodies
Fingernails
Eyelashes
Entropion (inward turning eyelid)
If the abrasion is associated with the use of contact lenses there may be infection with pseudomonas.
An important differential diagnosis to consider is herpes keratitis as this will require treatment with antiviral eye drops.
Chemical abrasions (e.g., from acid) can cause severe damage to the eye and loss of vision.
Presentation of corneal abrasions
History of contact lenses or foreign body
Painful red eye
Foreign body sensation
Watering eye
Blurring vision
Photophobia
Diagnosing corneal abrasions
A fluorescein stain is applied to the eye to diagnose a corneal abrasion. This is a yellow-orange colour. The stain collects in abrasions or ulcers, highlighting them.
Slit lamp examination may be used in more significant abrasions.
Managing corneal abrasions
NICE Clinical Knowledge Summaries on red-eye say patients with potentially sight-threatening causes of red eye should be referred for same-day assessment by an ophthalmologist. Mild, uncomplicated abrasions may be managed in primary care where there is appropriate experience and skill.
Management options include:
Removing foreign bodies
Simple analgesia (e.g. paracetamol)
Lubricating eye drops
Antibiotic eye drops (i.e. chloramphenicol)
Follow-up after 24 hours
Cyclopentolate eye drops dilate the pupil (they are mydriatics – causing mydriasis, meaning pupil dilation). They may be considered to help relieve symptoms, although evidence is lacking for their use in uncomplicated abrasions.
Chemical abrasions require immediate irrigation for 20-30 minutes and urgent referral to ophthalmology.
Uncomplicated corneal abrasions usually heal over 2-3 days.
Herpes keratitis
Keratitis is inflammation of the cornea. There are a number of causes of keratitis:
Viral infection with herpes simplex
Bacterial infection with pseudomonas or staphylococcus
Fungal infection with candida or aspergillus
Contact lens acute red eye (CLARE)
Exposure keratitis is caused by inadequate eyelid coverage (e.g. eyelid ectropion)
Herpes simplex infection is the most common cause of keratitis. This is called herpes simplex keratitis. It can cause inflammation in any part of the eye however it most commonly affects the epithelial layer of the cornea. Herpes simplex keratitis can be primary or recurrent.
Herpes keratitis usually affects only the epithelial layer of the cornea. If there is inflammation of the stroma (the layer between the epithelium and endothelium), this is called stromal keratitis. This is associated with complications such as stromal necrosis, vascularisation and scarring and can lead to corneal blindness.
Presentation of herpes keratitis
Painful red eye
Photophobia
Vesicles around the eye
Foreign body sensation
Watering eye
Reduced visual acuity. This can vary from subtle to significant.
Diagnosing herpes keratitis
Staining with fluorescein will show a dendritic corneal ulcer. Dendritic describes the appearance of branching and spreading of the ulcer.
Slit-lamp examination is required to find and diagnose keratitis.
Corneal swabs or scrapings can be used to isolate the virus using a viral culture or PCR.
Managing herpes keratitis
NICE Clinical Knowledge Summaries on red-eye say patients with potentially sight-threatening causes of red eye should be referred for same-day assessment by an ophthalmologist.
Management options in secondary care:
Aciclovir (topical or oral)
Ganciclovir eye gel
Topical steroids may be used alongside antivirals to treat stromal keratitis
A corneal transplant may be required after the infection has resolved to treat corneal scarring caused by stromal keratitis.
Subconjunctival haemorrhage
Subconjunctival haemorrhages are a relatively common condition where one of the small blood vessels within the conjunctiva ruptures and release blood into the space between the sclera and the conjunctiva. They often appear after episodes of strenuous activity such as heavy coughing, weight lifting or straining when constipated. It can also be caused by trauma to the eye.
TOM TIP: Most cases are idiopathic and the patient is otherwise healthy, however there are a number of conditions that may have predisposed them to developing a subconjunctival haemorrhage. When a patient turns up with a subconjunctival haemorrhage use it as a clue to think about other conditions that may have contributed:
Hypertension
Bleeding disorders (e.g thrombocytopenia)
Whooping cough
Medications (warfarin, NOACs, antiplatelets)
Non-accidental injury
Presentation of subconjunctival haemorrhage
A subconjunctival haemorrhage appears as a patch of bright red blood underneath the conjunctiva and in front of the sclera covering the white of the eye. It is painless and does not affect vision.
There may be a history of a precipitating event such as a coughing fit or heavy lifting.
They can be confidently diagnosed based on a simple history and examination.
Managing subconjunctival haemorrhage
Subconjunctival haemorrhages are harmless and will resolve spontaneously without any treatment. This usually takes around 2 weeks.
Think about the possible causes such as hypertension and bleeding disorders. These may need investigating further.
If there is a foreign body sensation lubricating eye drops can help with symptoms.
Posterior vitreous detachment
The vitreous body is the gel inside the eye that maintains the structure of the eyeball and keeps the retina pressed on the choroid. The vitreous body is made up of collagen and water. With age it becomes less firm and less able to maintain its shape. Posterior vitreous detachment is a condition is where the vitreous gel comes away from the retina. It is very common, particularly in older patients.
Presentation of posterior vitreous detachment
Posterior vitreous detachment is a painless condition. It may be completely asymptomatic or patients may present with symptoms of:
Painless
Spots of vision loss
Floaters
Flashing lights
Managing posterior vitreous detachment
No treatment is necessary. Over time the symptoms will improve as the brain adjusts.
Posterior vitreous detachment can predispose patients to developing retinal tears and retinal detachment. They can also present very similarly.
It is essential to exclude and assess the risk of a retinal tear or detachment with a thorough assessment of the retina. This is usually done by an optometrist or ophthalmologist.
Retinal detachment
Retinal detachment is where the retina separates from the choroid underneath. This is usually due to a retinal tear that allows vitreous fluid to get under the retina and fill the space between the retina and the choroid.
The outer retina relies on the blood vessels of the choroid for its blood supply. This makes retinal detachment a sight-threatening emergency unless quickly recognised and treated.
Risk factors for retinal detachment
Posterior vitreous detachment
Diabetic retinopathy
Trauma to the eye
Retinal malignancy
Older age
Family history
Presentation of retinal detachment
Retinal detachment is a painless condition that can present with:
Peripheral vision loss. This is often sudden and like a shadow coming across the vision.
Blurred or distorted vision
Flashes and floaters
Managing retinal detachment
Patients presenting with painless flashes and floaters should have a detailed assessment of the retina by someone with the appropriate skillset to detect retinal tears or detachment. Any suspicion of retinal detachment requires immediate referral to ophthalmology for assessment and management.
Management of retinal tears aims to create adhesions between the retina and the choroid to prevent detachment. This can be done using:
Laser therapy
Cryotherapy
Management of retinal detachment aims to reattach the retina and reduce any traction or pressure that may cause it to detach again. This needs to be followed by treating retinal tears as above. Reattaching the retina can be done using one of three options:
Vitrectomy involves removing the relevant parts of the vitreous body and replacing it with oil or gas.
Scleral buckling involves using a silicone “buckle” to put pressure on the outside of the eye (the sclera) so that the outer eye indents to bring the choroid inwards and into contact with the detached retina.
Pneumatic retinopexy involves injecting a gas bubble into the vitreous body and positioning the patient so the gas bubble creates pressure that flattens the retina against the choroid and close the detachment.
Retinal vein occlusion
Central retinal vein occlusion occurs when a blood clot (thrombus) forms in the retinal veins and blocks the drainage of blood from the retina. The central retinal vein runs through the optic nerve and is responsible for draining blood from the retina.
There are four branched veins that come together to form the central retinal vein. Blockage of one of the branch veins causes problems in the area drained by that branch whereas blockage in the central vein causes problems with the whole retina.
Blockage of a retinal vein causes pooling of blood in the retina. This results in leakage of fluid and blood causing macular oedema and retinal haemorrhages. This results in damage to the tissue in the retina and loss of vision. It also leads to the release of VEGF, which stimulates the development of new blood vessels (neovascularisation).
Presentation of retinal vein occlusion
Blockage of one of these retinal veins causes sudden painless loss of vision.
Risk factors for retinal vein occlusion
Hypertension
High cholesterol
Diabetes
Smoking
Glaucoma
Systemic inflammatory conditions such as systemic lupus erythematosus
Fundoscopy and retinal vein occlusion
Fundoscopy examination is diagnostic of retinal vein occlusion. It give characteristic findings:
Flame and blot haemorrhages
Optic disc oedema
Macula oedema
Other tests and retinal vein occlusion
The Royal College of Ophthalmologists guidelines from 2015 suggest checking for possible associated conditions in patients presenting with retinal vein occlusion:
Full medical history
FBC for leukaemia
ESR for inflammatory disorders
Blood pressure for hypertension
Serum glucose for diabetes
Managing retinal vein occlusion
Patients with suspected retinal vein occlusion should be referred immediately to an ophthalmologist for assessment and management.
Management in secondary care aims to treat macular oedema and prevent complications such as neovascularisation of the retina and iris and glaucoma. The options for this are:
Laser photocoagulation
Intravitreal steroids (e.g. a dexamethasone intravitreal implant)
Anti-VEGF therapies (e.g. ranibizumab, aflibercept or bevacizumab)
Central retinal artery occlusion
Central retinal artery occlusion occurs where something blocks the flow of blood through the central retinal artery. The central retinal artery supplies the blood to the retina. It is a branch of the ophthalmic artery, which is a branch of the internal carotid artery.
The most common cause of occlusion of the retinal artery is atherosclerosis. It can also be caused by giant cell arteritis, where vasculitis affecting the ophthalmic or central retinal artery causes reduced blood flow.
Risk factors for central retinal artery occlusion
Risk factors for retinal artery occlusion by atherosclerosis are the same as for other cardiovascular diseases:
Older age
Family history
Smoking
Alcohol consumption
Hypertension
Diabetes
Poor diet
Inactivity
Obesity
Those at higher risk for retinal artery occlusion secondary to giant cell arteritis are white patients over 50 years of age, particularly females and those already affected by giant cell arteritis or polymyalgia rheumatica.
Presentation of central retinal artery occlusion
Blockage of the central retinal artery causes sudden painless loss of vision.
There will be a relative afferent pupillary defect. This is where the pupil in the affected eye constricts more when light is shone in the other eye compared when it is shone in the affected eye. This occurs because the input is not being sensed by the ischaemic retina when testing the direct light reflex but is being sensed by the normal retina during the consensual light reflex.
Fundoscopy will show a pale retina with a cherry-red spot. The retina is pale due to a lack of perfusion with blood. The cherry-red spot is the macula, which has a thinner surface that shows the red coloured choroid below and contrasts with the pale retina.
Managing central retinal artery occlusion
Patients with suspected central retinal artery occlusion should be referred immediately to an ophthalmologist for assessment and management.
Giant cell arteritis is an important potentially reversible cause. Therefore older patients are tested and treated for this if suspected. Testing involves an ESR and temporal artery biopsy and treatment is with high dose steroids (i.e. prednisolone 60mg).
Immediate management of central retinal artery occlusion
If the patient presents shortly after symptoms develop then there are certain things that can be tried to attempt and dislodge the thrombus. None of these have a strong evidence base. Some examples are:
Ocular massage
Removing fluid from the anterior chamber to reduce intraocular pressure.
Inhaling carbogen (a mixture of 5% carbon dioxide and 95% oxygen) to dilate the artery
Sublingual isosorbide dinitrate to dilate the artery
Long term management of central retinal artery occlusion
Long term management involves treating reversible risk factors and secondary prevention of cardiovascular disease.
Retinitis pigmentosa
Retinitis pigmentosa is a congenital inherited condition where there is degeneration of the rods and cones in the retina. There are many different genetic causes. Some causes involve isolated retinitis pigmentosa whereas others result in systemic diseases associated with the condition. They vary in age at presentation and prognosis.
In most genetic causes the rods degenerate more than cones, leading to night blindness. They get decreased central and peripheral vision.
Presentation or retinitis pigmentosa
The presentation can vary between different underlying causes. Family history is very important. In most causes the symptoms start in childhood.
Night blindness is often the first symptom
Peripheral vision is lost before the central vision.
Fundoscopy of retinitis pigmentosa
Fundoscopy will show pigmentation. This is described as “bone-spicule” pigmentation. Spicule refers to sharp, pointed objects. Bone-spicule is used to refer to the similarity to the networking appearance of bone matrix.
The pigmentation is most concentrated around the mid-peripheral area of the retina.
There can be associated narrowing of the arterioles and a waxy or pale appearance to the optic disc.
Associated systemic diseases to retinitis pigmentosa
There are several genetic systemic diseases that involve retinitis pigmentosa. It is not worth learning the names and details but it is worth being aware they exist. Some examples are:
Usher’s Syndrome causes hearing loss plus retinitis pigmentosa
Bassen-Kornzweig Syndrome is a disorder of fat absorption and metabolism causing progressive neurological symptoms and retinitis pigmentosa
Refsum’s Disease is a metabolic disorder of phytanic acid causing neurological, hearing and skin symptoms and retinitis pigmentosa
Managing retinitis pigmentosa
General management involves:
Referral to an ophthalmologist for assessment and diagnosis
Genetic counselling
Vision aids
Sunglasses to protect the retina from accelerated damage
Driving limitations and informing the DVLA
Regular follow up to assess vision and check for other potentially reversible conditions that may worsen the vision such as cataracts
There isn’t a huge amount of evidence supporting options to slow the disease process. Some options that may be considered by a specialist in certain scenarios include:
Vitamin and antioxidant supplements
Oral acetazolamide
Topical dorzolamide
Steroid injections
Anti-VEGF injections
Gene therapy is a potential future treatment that could alter the disease process and lead to better outcomes.
