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.