Eyelids Flashcards
Layers of the eyelid (anterior to posterior)
Skin
Orbicularis muscle
Tarsal plate (fibrous)
Levator muscle
Muller muscle
Lamellae of the eyelids
Anatomically divided into 2 lamellae by the Gray line (outermost margin of the Orbicularis muscle)
- Anterior lamella contains: skin and orbicularis
- Posterior lamella contains: tarsal plate and conjunctiva
Landmarks of upper vs lower lid
Normally, the upper lid is 2mm below the superior limbus and the lower lid is at the level of the inferior limbus
What forms the tarsal plates?
The orbital septum
What maintains the shape of the eyelids?
The tarsal plates
How can depth of an eyelid laceration be catagorised?
Layer of preaponeurotic fat pads just posterior to the orbital septum
If the fat pads are visible then it is a deep laceration involving the posterior lamella
What landmarks differentiates orbital vs pre-orbital cellulitis
The orbital septum
Muscles which cause retraction of eyelid
- The levator innervated by CN3
- Frontalis (muscle of facial expression) innervated by CN7
- Muller’s muscle under sympathetic innervation
Main muscle of eyelid closure?
Orbicularis oculi innervated by CN7
What muscles has an important role in the lacrimal pump mechanism
Orbicularis oculi - its action guides the flow of tears across the ocular surface
Blink reflex
Afferent Limb (3 inputs paths)
* Corneal stimulus via CNV1
* Light stimulus via CN2
* Auditory stimulus via CN8
Efferent limb (1 effector path)
Via CN7 to the Orbicularis oculi muscle, which controls lid closure
What is Bell’s phenomenon?
Normal physiological finding where the globe rotates up and out during forced lid closure
Poor Bell’s phenomenon?
Is a risk factor for lagophthalmos
What are the Canthal tendons?
- The canthal tendons keep the eyelid structure stable
- 2 in each orbit: medial and a lateral
- Attach to the tarsus of the upper and lower eyelids
Anatomical location of the lacrimal sac?
The lacrimal sac lies between the limbs of the medial canthal tendon
What is the palpebral fissure?
The gap between the upper and lower eyelid margins.
Thyroid eye disease and the eyelid
Retraction
Muller contraction
Horner syndrome and the eyelid
Ptosis
Muller relaxation
CN7 palsy and the eyelid
Lagophthalmos due to Orbicularis spasm
CN3 palsy and the eyelid
Ptosis
Levator relaxation
What is Lagophthalmos?
Why is it dangerous?
Inability to fully close the eyelids (palpebral fissure)
Leads to exposure keratopathy, which can be sight-threatening.
Types of lid reconstruction
Can both lamellae be repaired with grafts?
No because there would be no blood supply
How is the anterior lamella reconstructed?
Anterior advancement → incise and stretch tissue over the laceration
Transposition → move tissue from the other lid
Rotation → rotated skin from the cheek
Glabella → rotated diamond-shaped forehead skin
How is the posterior lamella reconstructed?
Hughs Flap → flap taken from the upper lid
Free tarsal graft from the fellow eye → tissue taken from the other eye
In a full-thickness laceration of the lid, which lamella is reconstructed first?
The posterior lamella is repaired before the anterior lamella
Blepharitis
Chronic inflammation of the eyelid of any cause.
Typically associated with Staphylococcus aureus infection.
Classification of Blepharitis
Anterior - Affects the base of the eyelashes
2 further subtypes:
* Seborrhoeic (excessive secretions)
* Staphylococcal (direct infection)
Posterior - Affects the Meibomian glands
Does anterior or posterior blepharitis have a better response to treatment?
Anterior, because it occurs at the surface level.
Blepharitis presentation
Bilateral crusting of the lids and lashes
Foamy tear film and meibomian cysts are seen specifically with posterior blepharitis.
The lashes can appear normal in posterior blepharitis
Unilateral blepharitis must be investigated for what?
Sebaceous cell carcinoma!
Atopic dermatitis is associated with what type of blepharitis
Staphylococcal
Seborrheic dermatitis is associated with what type of blepharitis
Seborrheic
Acne rosacea is associated with what type of blepharitis
Posterior
Management of blepharitis
Lid hygiene
Warm compress
Topical lubrication and tetracyclines
How do tetracyclines treat blepharitis?
limit fatty acid production which can decrease the inflammatory secretions
Meibomian Gland Dysfunction
chronic disorder of the meibomian glands that overlaps with posterior blepharitis. It is characterised by duct obstruction and abnormal glandular secretions, which result in a characteristically foamy tear film
Pathology of MGD
Secretion of the meibomian oil is obstructed → stagnation within glands → inflammation →staphylococcal colonisation → chronic inflammation and scarring
Function of meibomian glands
Secrete a lipid layer which contributes to the tear film.
Functions of this layer is to help keep the tear film stable
What is Meibomianitis?
Type of MGD where inflammation is marked
It is associated with acne rosacea and worse in the mornings with thick secretions and duct inflammation
Presentation of MGD
Foamy tear film
Crusty eyelashes
Gritty irritated eyes
Investigations for MGD
- Tear film breakup time of <5 seconds is a sign of tear film instability
- Fluorescein staining of the cornea shows corneal epithelial damage
Management of MGD
Determined by clinical classification
Untreated MGD can lead to?
MG cysts, trichiasis, blepharitis, and keratitis
What is Trichiasis?
Trichiasis is the inward misdirection of the eyelashes. This can lead to corneal irritation and ulceration.
Distichiasis
A congenital abnormality where there are 2 rows of eyelashes. Can be associated with Meige syndrome
Acquired metaplastic lashes
Abnormally positioned lashes due to inflammation such as meibomitis and scarring
Pseudotrichiasis
Inwardly projecting lashes due to entropion
Types of Trichiasis?
Distichiasis
Acquired metaplastic lashes
Pseudotrichiasis
Management of Trichiasis
Epilation - Recurrence is common so this is a temporising measure
Lash destruction by electrolysis/laser/cryotherapy - typically used when there is only a limited collection of abnormal lashes. Scarring and inflammation can be worsened.
Surgery - A pentagon excision can be used to remove focal groups of lashes.
How are benign lid lumps classified?
Based on location: anterior or posterior lamella
Hordeolum (stye)
A painful lid abscess caused by Staphylococcus infection.
Hordeolum classification
External (anterior lamella): abscess of Zeis or Moll glands
Internal (posterior lamella): abscess of Meibomian glands
Presentation of hordeolum
Painful nodule
Commonly affects the upper eyelid
Diagnosis is clinical
Management of hordeolum
Hot compress
Oral antibiotics
Key difference between Hordeolum vs chalazion
chalazion is a painless nodule
Pathology of Chalazion
Obstruction of Meibomian or Zeis glands leads to sterile lymphogranuloma formation
Presentation of chalazion
Painless upper eyelid nodule
Management of chalazion
Hot compress is the only management that is usually required
Surgical incision and curettage is an option but rarely needed
Anterior Lamella Cysts
Cyst of Moll and Cyst of Zeis are chronic benign anterior lamella cysts.
They are often self-limiting but can be excised or treated with diathermy
Compare a cyst of Moll vs Zeis
Cyst of Moll - chronic translucent cyst arising from blockage of Moll glands
Cyst of Zeis - chronic non-translucent cysts arising from blockage of Zeis glands
commonest cancer in ophthalmology
Basal Cell Carcinoma
Basal Cell Carcinoma features
- Most commonly occurs on lower lid of eye and upper lip of the mouth
- It is a slow-growing lesion and does not typically spread
- The lesion is pearly white with associated telangiectasia
BCC management
Surgical resection
Mohs Micrographic surgery can for used in high-risk cases where the lesion margins are uncertain
What is Vismodegib?
Vismodegib is a medication approved for non-resectable cases and works through the Hedgehog pathway.
BCC is associated with Ptch/Smo gene mutation in the Hedgehog pathway
Squamous Cell Carcinoma is associated with what two populations?
HPV and immunocompromise
Pathology of SCC
Aggressive and spreads via lymphatics
Histology shows epidermal proliferation, atypical keratinocytes, and squamous eddies
Management of SCC
Surgical excision, radiotherapy, chemotherapy
Melanoma pathology
- Melanoma is not always pigmented.
- Most likely to arise from the choroid inside the eye (highest concentration of melanin)
- Spreads to the liver
- Breslow thickness is the prognostic indicator
Melanoma management
Surgical excision, radiotherapy, chemotherapy
What is vemurafenib
Vemurafenib is a kinase inhibitor with FDA approval for unresectable melanomas
Sebaceous Gland Carcinoma arise from?
Meibomian and Zeis glands
Pathology of Sebaceous gland carcinoma
Can be misdiagnosed as unilateral blepharitis.
Spreads to lymph nodes and viscera
Associated with Muir Torre syndrome
Management of Sebaceous gland carcinoma
Surgical excision, radiotherapy, chemotherapy
Prognosis is poor
Entropion and ectropion most commonly affect which lid?
lower eyelids
Ptosis most commonly affects which lid?
upper eyelids
Ectropion
Outwardly pulled eyelid. It can stop the eyes from closing properly (lagophthalmos).
This can compromise the tear film and cause ocular surface irritation.
Types of ectropion
Most common type of ectropion
Involutional - Caused by horizontal lid laxity and often seen in the elderly
Management of ectropion
Depends on the mechanism of ectropion:
Horizontal lid laxity → lateral tarsal strip
Vertical lid laxity → Diamond excision
Cicatrix → skin gaining procedures such as grafts and flaps
Entropion
Entropion is an inwardly rolled eyelid. It can lead to corneal ulceration as the inwards turning eyelashes rub against the cornea whilst blinking.
Types of Entropion
- Involutional (Commonest type) - caused by lower retractor weakness/dehiscence.
- Cicatricial - caused by shortening of the posterior lamella by vertical scarring.
Most commonly caused by trachoma (upper lid)
Management of Entropion
Depends on the mechanism of entropion
Retractor weakness → Everting sutures, transverse tarsotomy, or Jones procedure
Scarring → Membrane graft or posterior lamella reconstruction
Botox can be used to weaken overactive muscles
Ptosis
An abnormally droopy upper eyelid. It can be congenital but is most commonly acquired.
Types of ptosis
Involutional (commonest)
Neurogenic
Congenital Ptosis
Pseudoptosis
Involutional ptosis
The most common type.
Caused by dehiscence of the levator palpebrae superioris from its attachment to the levator aponeurosis.
Risk is increased with age and after surgery.
Treatment → anterior levator advancement surgery
Neurogenic ptosis
CN3 Palsy
* Loss of levator function leads to ptosis.
* Abnormalities in eye movements and a mydriatic pupil can also be seen.
* Spontaneous resolution is common so treatment (with frontalis suspension surgery) is typically delayed
Horner Syndrome
* Surgical management is with Levator resection (strengthens muscle) or Mullerectomy.
Myasthenia Gravis
Congenital Ptosis
Isolated congenital ptosis
* Developmental myopathy of the LPS
* Typically unilateral, with an absent upper lid crease.
* Treatment depends on levator function:
* Poor function → frontalis suspension.
* Preserved function → anterior levator resection.
Blepharophimosis syndrome
* Characterised by a shortened horizontal palpebral fissure and telecanthus.
* AD inheritance
Marcus Gunn jaw-winking syndrome
* Characteristic elevation of the ptotic lid whilst chewing.
* Thought to be caused by developmental CN5 misdirection to the LPS
Pseudoptosis
Pseudoptosis is a lid that appears droopy, but is actually within normal range when measured.
Blepharochalasis - abnormally elastic lid tissue leads to excess skin folds and oedema
Dermatochalasis - commonly seen in the elderly. Upper lid skin hangs and folds.
Brow ptosis
Frontalis dysfunction leads to lowering of the entire eyebrow region.
