Flashcards in Diseases of the External Eye Deck (52)
What are the two main varieties of blepharitis?
Staphylococcal (epidermis or aureus) and seborrhoeic blepharitis.
However, both types of blepharitis frequently overlap and may be indistinguishable from each other.
True or false: symptoms of blepharitis may be severe despite minimal signs being present.
What the the signs associated with staphylococcal blepharitis?
The lid margin is inflamed and coated with scales.
The lashes are stuck together by crusts.
What are the signs associated with seborrhoeic blepharitis?
The lid margin is less inflamed than in staphylococcal blepharitis.
Plugs of sebum in the meibomian gland.
Foamy tear film.
What is the abnormality in seborrhoeic blepharitis?
An overproduction of sebum by glands at the lid margin (especially the meibomian glands). Bacteria metabolise the sebum, producing irritant free fatty acids.
What are two main complications of both types of blepharitis?
1. Secondary conjunctivitis (which may not be infective)
2. Punctate corneal epithelial erosions (seen after instillation of fluorescein and examination with blue light).
Name 8 other associations with blepharitis.
1. Dry eye (disturbance of tear film)
2. Corneal scarring and vascularisation (especially inferior cornea)
3. Peripheral corneal ulceration and infiltration
4. Eyelash abnormalities (eg. Trichiasis)
5. Stye (external hordeolum, a bacterial eyelash folliculitis)
6. Internal hordeolum (acute bacterial meibomian gland infection)
7. Chalazion (meibomian gland lipogranuloma)
8. Acne rosacea (erythema, pustules, hypertrophic sebaceous glands, rhinophyma)
What are the three principles of management of blepharitis?
1. Lid hygiene (rub away scales, crusts, sebum; reduce bacterial load; express plugged meibomian glands)
2. Antibiotics (eg. Chloramphenicol OINTMENT clings to lid margin better than drops; systemic ABx in severe or persistent cases (tetracycline, doxycycline for 6-12 weeks).
3. Artificial tear drops (as often as necessary)
Note: emphasise to pts that condition is chronic and relapsing-remitting; complete cure may not be possible.
What may provide relief in acute infections of the eyelid (external or internal hordeolum)?
If severe, especially if associated cellulitis, surgical drainage and systemic ABx may be required.
What are some features of eyelid/periorbital contact dermatitis?
Erythema, swelling and scales of eyelid skin.
Medications administered to the eye may be the fault, and will cause an associated conjunctivitis. The dermatitis will extend down onto the cheek, where the medication spills out.
Dermatitis usually allergic (contact) or in association with eczema.
With eyelid lumps, name four features typical of an acutely infective cause:
4. Purulent discharge
The sterile chalazion is also common.
Name three types of retention cysts of the eyelid.
1. Retention cyst of Möll (sweat gland): thin-walled margin cyst containing clear fluid.
2. Retention cyst of Zeiss (sebaceous gland): sebum-containing lid margin cyst.
3. Sebaceous retention cyst: sebum-containing cyst.
Retention cysts are benign and can safely be left alone (but pts often request their removal).
Name 5 categories of eyelid lumps.
1. Infections (stye, internal hordeolum, molluscum contagiosum, viral warts)
2. Inflammation (ie. chalazion)
3. Retention cysts (Möll, Zeiss, sebaceous)
4. Benign tumours (papilloma, seborrhoeic keratosis, senile keratosis, xanthelasma, keratocanthoma, cutaneous horn, haemangioma, naevus).
5. Malignant tumours (BCC, SCC, sebaceous gland carcinoms, melanoma). *BCC most common malignant lump.
How much of the cornea is covered by the normally positioned eyelid?
1-2mm of the cornea.
In ptosis, the upper eyelid margin lies below this level.
Which muscles and cranial nerve are involved in lifting the eyelid?
Levator palpebrae + sympathetic smooth muscle component (Muller's muscle).
CN III (oculomotor).
Which muscle and cranial nerve close the eyes?
What two situations can mimic a ptosis?
Enophthalmos (a sunken eye, which may follow an orbital fracture).
OR a proptosed/large eye may give appearance of ptosis in the other (normal) eye.
What is dermatochalasis?
Excess of upper lid skin. Can also mimic ptosis.
Name 6 causes of ptosis (always consider congenital vs acquired).
1. Involutional (ageing) changes (common, usually bilateral).
2. Third nerve palsy (will also have divergent squint & sometimes dilated pupil).
3. Myasthenia gravis
4. Trauma to the levator muscle.
5. Horner's syndrome.
6. Mitochondrial myopathies (retinal pigmentation, like retinitis pigmentosa, can also occur).
Any of these causes may result in congenital ptosis, although this is usually idiopathic or part of congenital Horner's.
What are three important causes of a third nerve palsy?
1. Diabetes mellitus
3. Expanding intracranial aneurysm (rarely).
What are the features of eye symptoms in myasthenia gravis?
May present with ocular signs before systemic disease.
Typically, ptosis is variable, becoming worse with effort and therefore worse at the end of the day.
There may also be abnormal eye movements, causing double vision.
What are the features of Horner's Syndrome, and why is there ptosis?
1. Ptosis, small pupil, sometimes dryness and flushing of facial skin on the affected side.
2. In Horner's, sympathetic innervation of Muller's muscle is disrupted at any point along the course of the sympathetic pathway through important sites in including the brainstem (in association with other neurological signs) and in the neck, particularly due to invasive lung cancer.
What is one facial sign of ptosis?
Wrinkling of the forehead.
Caused by compensatory contraction of the frontalis muscle, which has some attachment to the upper lid. An overacting frontalis muscle should be neutralised by pressing firmly against the brow to prevent transference of contracting force from forehead to lid.
What is a possible management option for involutional (ageing) ptosis?
Surgical restoration of the connections between levator and eyelid skin is commonly performed.
How is myasthenia managed?
Acetylcholinesterase inhibitors (increase availability of ACh) and immunosuppressants.
What is a possible concern resulting from elevating the lid in third nerve palsy?
May produce disabling double vision.
Does entropion (turning inwards of the lid margin) affect the upper lid or lower lid?
Can affect both.
In the UK, upper lid entropion is rare, but worldwide it is more common dud to the contractile scarring process which occurs in trachoma.
Name three causes of entropion.
1. Involutional (ageing) processes.
2. Conjunctival scarring (cicatricial, trachoma, alkaline burns, Stevens-Johnson syndrome). Pull eyelid away and look for adhesions across conjunctival fornix.
3. Spasm of orbicularis oculi (primary and secondary).
What are the ocular consequences of entropion?
The inwardly turning lid causes eyelashes to rub against eyeball.
Pt has foreign body type sensation and reflex watering.
Abrasive eyelashes may cause corneal abrasion/ulceration with risk of bacterial corneal infection. Ulceration requires urgent ophthal referral.
Management of entropion?
Most cases fine with simple surgical procedure.
Scarring very hard to overcome.
Blepharospasm treated with repeated botox a injections.
Name 4 causes of ectropion.
1. Involutional (ageing) changes
2. Facial nerve palsy
3. Eyelid skin scarring (cicatricial)
4. Bulky eyelid tumours
Does ectropion affect upper or lower lid?
Ocular consequences of ectropion?
Mainly watering, as normal collection of tears into punctum is impaired.
Exposed lid may become inflamed and keratinised.
Corneal exposure (incl. ulceration) may result from extreme ectropion and requires specialist referral.
How is ectropion managed?
Involutional, permanent facial nerve palsy and cicatricial ectropion managed with surgical procedure.
Likely facial nerve palsy recovery - usually lubricating ointment, but if cornea at risk, then perform a temporary lateral tarsorrhapy (eyelids sutured together).
Dry eye syndrome can result from a deficiency in any one of three what?
Three components of tear film: outer lipid, middle aqueous and inner mucin layers.
Lipid layer produced by Meibomian glands.
95% of aqueous component is secreted by main lacrimal gland; additional secretion by accessory glands in conjunctiva.
Inner mucinous layer produced mainly by conjunctival goblet cells.
What is aqueous tear deficiency also known as?
What is the most common cause of dry eye syndrome?
Aqueous tear deficiency, aka keratoconjunctivitis sicca.
The aqueous layer of tear film smooths the optical interface, washes away debris and conveys oxygen and antibacterial elements to the corneal and conjunctival surfaces.
What is lacrimal gland dysfunction (leading to aqueous tear deficiency) usually caused by?
Inflammation, especially autoimmune.
Other causes include scarring of the secretory ducts and excision of the lacrimal gland.
Pure keratoconjunctivitis sicca involves the lacrimal gland alone.
If salivary and other glands are involved in an autoimmune process, primary Sjögren's syndrome is used. Secondary Sjögren's is found as part of a systemic autoimmune disorder such as rheumatoid arthritis.
What is mucin deficiency known as, and what are two ways it can occur?
Occurs when a large number of goblet cells are damaged by extensive conjunctival scarring (alkali burn, cicatrising conjunctival disease).
Also can be caused by hypovitaminosis A (inadequate production).
What is an irritative eye condition which is usually found in association with a disturbance in the production of the lipid component of tear film?
Poor tear film quality is common (vs pure aqueous deficiency) and is especially associated with which irritative eye condition?
Chief symptom is persistent irritation, often with a feeling of dryness.
Identification of the clinical features of dry eye is best performed how?
Slit lamp examination with fluorescein or rose bengal dye (for examination of tear film and staining of punctate epithelial erosions in the cornea and conjunctiva). Mucus strands and debris may also be seen.
Which objective test can be used for dry eye, despite being unreliable?
Involves wetting a strip of filter paper from the eye.
What are three corneal consequences of dry eye? Plus two rare consequences?
1. Corneal epithelial loss
1. Corneal thinning (melt) (eg. In a pt with RA)
What are the three management options for dry eye (in addition to the three options for blepharitis)?
1. Conservative: reduce tear evaporation via room humidification or attachment of side pieces to spectacles.
2. Tear supplements
3. Lacrimal puncta, occlusion (temporary or permanent)
Recall blepharitis: regular lid hygiene, restore Meibomian gland function, antibiotics.
What is inappropriate watering of the eye called and what are two general reasons it may occur?
1. Failure of lacrimal drainage system
2. Oversecretion of tears
Oversecretion follows ocular irritation by eyelashes and even, paradoxically, as a reflex to the ocular irritation that accompanies blepharitis and dry eye states.
What are two reasons for failure of the lacrimal drainage system?
1. Obstruction (congenital or acquired)
2. Failure of the lacrimal pump mechanism (which propels tears into the lacrimal sac).
Obstruction (congenital) - failure of complete development of the nasolacrimal duct, which may continue to develop in infancy leading to spontaneous resolution. After 9 months, surgical probe fix under GA.
Obstruction (acquired) - distal nasolacrimal duct by involutional changes is most common, but may occur anywhere along drainage pathway. May require a bypass procedure (dacrocystorhinostomy - major operation which links sac to nasal cavity by removal of intervening bone). Alternatively, creation of bypass channel with endonasal laser is increasingly popular as a day procedure.
What are the two usual causes for failure of the lacrimal pump?
1. Facial nerve palsy
ie. may lead to epiphora.
On inspection, what two things could one see if a nasolacrimal duct obstruction was present (causing epiphora)? Where do they appear, and what distinguishes one from the other?
1. Mucocele (a non-infected swelling of lacrimal sac)
2. Dacrocystitis (lacrimal sac infection).
Both appear as swellings at the medial canthus. Contents of mucocele may be expressed into conjunctival fornix by digital pressure. Acute dacrocystitis is a tender, red swelling, often with a purulent point of discharge.
How could you investigate an obstruction of the drainage system causing epiphora?
Instil anaesthetic drops and gently probe using a cannula attached to a syringe of saline solution.
Punctal stenosis will prevent insertion of the cannula.
Canaliculus obstruction will prevent cannula passage into the lacrimal sac.
If the sac can be entered, regurgitation of saline indicates nasolacrimal duct obstruction.
If saline tasted (nasopharynx), indicates either partial obstruction or functional drainage failure.
What is it called when a radio-opaque dye is injected into the lacrimal drainage system?