1. Intro to AED

Question 1

What is the agreeed terminology of Bowman’s membrane and Descemet’s membrane respectively?

Answer 1

• Bowman’s membrane = Anterior limiting lamina
• Descemet’s membrane = Posterior limiting lamina

Question 2

Name the 5 different general areas of the anterior eye.

Answer 2

• Cornea & limbus
• Tear film
• Conjunctiva & Sclera
• Eyelids & Eyelashes
• Lacrimal system

Question 3

Name 4 ways to clinically examine the anterior eye

Answer 3

• Hx taking
• Slit lamp biomicroscopy + Photodocumentation + Standardised grading scales
• Tear film assessment
• Specialised techniques may be required → req referral to ophthalmologist

Question 4

How would you assess whether a red eye is caused by conjunctival injection?

Answer 4

Use a cotton bud to manoeuvre the conjunctiva. If the red blood vessels move, it indicates that the redness is superficial, thus is the conjunctiva.

Question 5

What does ciliary redness indicate? Give 3 examples.

Answer 5

Disorders of deeper tissues & intraocular structures. Episcleritis, scleritis, disciform keratitis, iritis, cyclitis

Question 6

What disorders does regional/ sectorial/ pericorneal redness indicate? What should we pay attention to?

Answer 6

Look at the pattern of redness. Herpatic keratitis, rosacea, corneal lesions near the limbus, foreign body etc.

Question 7

The cornea consists of ..., ..., ..., stroma, ..., endothelium. Average thickness of the cornea is ...μm. The cornea is one of the most ... tissues of the body, approximately ... times. The cornea is innervated by the ..., which then branches as ... in the stroma, up through the ..., epithelium and eventually traverses upwards to the ....

Answer 7

The cornea consists of tear film, epithelium, anterior limiting lamina, stroma, posterior limiting lamina, endothelium. Average thickness of the cornea is 540-550μm. The cornea is one of the most sensitive tissues of the body, approximately 500 times. The cornea is innervated by the CN5 Trigeminal nerve, which then branches as stromal nerves in the stroma, up through the basal lamina, epithelium and eventually traverses upwards to the tear film.

Question 8

Corneal nerves can be used as a ... marker for certain ... conditions. For example, .... In comparison to healthy corneas, individuals with ... have a ... of nerves.

Answer 8

Corneal nerves can be used as a surrogate marker for certain systemic conditions. For example, diabetic neuropathy. In comparison to healthy corneas, individuals with diabetic neuropathy have a lower density of nerves.

Question 9

What are the 2 types of corneal immune cells? When are these cells implicated?

Answer 9

• Epithelial dendritic cells
• Stromal macrophages
  Found mostly in the peripheral cornea and implicated in dry eye disease, diabetic neuropathy, allergy and contact lens wear

Question 10

Corneal ... cells are responsible for both innate and ... immune responses. In ..., corneal ... rapidly respond to ocular surface ..., such as .... Corneal ... also respond to ..., ... and ... infections.

Answer 10

Corneal dendritic cells are responsible for both innate and adaptive immune responses. In innate, corneal DCs rapidly respond to ocular surface changes, such as CLs wear. Corneal DCs also respond to viral, bacterial and fungal infections.

Question 11

What are the 5 groups of components within human tears?

Answer 11

• Proteins (lysozyme, lactoferrin)
• Electrolytes
• Growth factors & suppressors of inflammation
• Soluble mucins
• Immunoglobulins

Question 12

The lacrimal functional unit is important for ..., including ..., ... and .... The unit includes the ..., ocular surface components, ..., ... and associated ... and ... nerves. Humans produce ... basal tears per year. Neural input mediates ... and ... of tears produced.

Answer 12

The lacrimal functional unit is important for tear film homeostasis, including tear production, distribution and clearance. The unit includes the lacrimal gland, ocular surface components, meibomian glands, eyelids and associated sensory and autonomic nerves. Humans produce 75L basal tears per year. Neural input mediates rate and type of tears produced.

Question 13

What are the 3 types of tears?

Answer 13

• Basal
• Reflex
• Emotional

Question 14

Basal tears are ... tears that bathe the .... It has the highest overall ... compared to other types of tears.
... are protective response to ... stimulation.... can be triggered by other bodily functions, such as ..., ... and .... This type of tears is ... higher in volume but is also relatively ..., consisting mostly of ....
Emotional tear is elicited in response to .... As a result, emotional tears consist of unique ... and ....

Answer 14

Basal tears are basic functional tears that bathe the ocular surface. It has the highest overall compositional complexity compared to other types of tears.
Reflex tears are protective response to irritants/ mechnical stimulation. Reflex tears can be triggered by other bodily functions, such as vomiting, coughing and yawning. This type of tears is 100x higher in volume but is also relatively dilute, consisting mostly of water.
Emotional tear is elicited in response to strong emotional response. As a result, emotional tears consist of unique stress hormones and proteins.

Question 15

What are the 3 components of the lacrimal system? Name the associated structures of each.

Answer 15

• Secretory: lacrimal gland + accessory glands
• Distribution: tear meniscus + blinking
• Drainage: puncta, lacrimal canaliculi, lacrimal sac & lacrimal duct

Question 16

Corneal staining is a ... technique in observing ....
... permeates into ... and therefore can indicate compromised corneal and ... epithelial ... junctions.
... is more useful for visualising ... anomalies. It identifies epithelial cells that lack a ... and/ or ... and mucus. It can also be used to detect early stages of ... when NaFl staining may not yet be apparent.

Answer 16

Corneal staining is a non-specific technique in observing ocular surface damage.
Sodium fluorescein permeates into intercellular spaces and therefore can indicate compromised corneal and conjunctival epithelial cell-to-cell junctions.
Lissamine green is more useful for visualising conjunctival anomalies. It identifies epithelial cells that lack a mucin coating and/ or degenerated cells and mucus. It can also be used to detect early stages of dry eye when NaFl staining may not yet be apparent.

Question 17

What are the differences between corneal staining vs conjunctival & lid wiper staining?

Answer 17

Corneal staining requires the use of only sodium fluorescein and a Wratten filter. Conjunctival and lid wiper staining is performed after fluorescein staining, using Lissamine green. 2 drops of LG is instilled with 2 separate paper strips. The lids are usually everted for better visualisation.

Question 17

What common conditions can be miscategorised as superficial punctate keratitis (SPK)? What is the distinguishing factor?

Answer 17

SPK implies inflammation. Conditions such as punctate epithelial erosions (PEE), punctate corneal staining and micropunctate staining are commonly misidentified as SPK, however they do not involve active inflammation.

Question 17

Ocular surface staining commonly arise with px who have ... and thus should expect staining at the ... part of the cornea;
Px with eye toxicity, we should expect ... throughout the cornea;
Px with ... in their eye, we should expect tracking of staining.
Moreover, dry eye disease, ..., ..., eyelid diseases (...) and ... diseases (infection/ inflammation) are common causes of ocular surface staining.
The ... of staining are helpful in identifying .... They can be ... or px might experience gritty eyes, ..., or ... if staining impedes visual axis.

Answer 17

Ocular surface staining commonly arise with px who have incomplete blinks and thus should expect staining at the inferior part of the cornea;
Px with eye toxicity, we should expect diffused staining throughout the cornea;
Px with FB in their eye, we should expect tracking of staining.
Moreover, dry eye disease, contact lenses, hypoxia, eyelid diseases (Blepharitis) and corneal diseases (infection/ inflammation) are common causes of ocular surface staining.
The location of staining are helpful in identifying aetiology. They can be asymptomatic or px might experience gritty eyes, photophobia, or reduced VA if staining impedes visual axis.

Question 17

... defines the point between the superficial eyelid skin to the conjunctiva. In an unhealthy eye, there will be lots of ... created and thus ... the tissues. Staining with ... will highlight ..., which is the ... of the lid wiper region. In a healthy eye, the line of Marx ....

Answer 17

Line of Marx defines the point between the superficial eyelid skin to the conjunctiva. In an unhealthy eye, there will be lots of friction created and thus damages the tissues. Staining with Lissamine green will highlight lid wiper epitheliopathy, which is the inflammation of the lid wiper region. In a healthy eye, the line of Marx will be faintly present.

Question 17

What type are Meibomian glands and what are their functions? What disease is commonly associated with Meibomian glands?

Answer 17

Meibomian glands are exocrine and they secrete meibum.
Meibomian gland dysfunction is a common cause of evaporative dry eyes. MGD is a chronic, diffuse abnormality of the MG. It is commonly characterised by terminal duct obstruction and or qualitative/ quantitative changes in the glandular secretion.

Question 18

What are the 3Es of meibomian gland assessment?

Answer 18

1. Evaluate lid margin & meibomian gland orifices
2. Express glands
3. Examine secretion colour & consistency

Question 19

In MGD, while evaluating the lid margins and meibomian gland orifices, we would observe ... and ... lid margins, and also ..., dilated, ... or retrodisplaced .... In some cases, the orifices can be ... or .... Excretions from Px with MGD will appear ... and ... or have ....

Answer 19

In MGD, while evaluating the lid margins and meibomian gland orifices, we would observe scalloped and thickened lid margins, and also capped, dilated, pouted or retrodisplaced meibomian gland orifices. In some cases, the orifices can be obliterated or scarred. Excretions from Px with MGD will appear cloudy and inspissated or have no secretions.

Question 20

Meibography is the ... visualisation of gland ... and .... Evaluation may inform ..., prognosis and potential ... of MGD. Meibomian gland ... is the permanent loss of some ....

Answer 20

Meibography is the in vivo visualisation of gland morphology and atrophy. Evaluation may inform severity, prognosis and potential treatment efficacy of MGD. Meibomian gland atrophy is the permanent loss of some meibomian glands.

Question 21

Microcornea is an uncommon ... abnormality which is inherited through ... genes. This abnormality can be ... in presentation. This is characterised by having horizontal corneal diameter of ... in infants or ... in adults. Other presentations include ..., ..., hyperopia etc. Px with microcornea can be ... and can be associated with other systemic conditions, such as ..., Nance-Horgan, ..., Turner’s, Waadenburg’s and ....

Answer 21

Microcornea is an uncommon congenital abnormality which is inherited through autosomal dominant or recessive genes. This abnormality can be unilateral or bilateral in presentation. This is characterised by having horizontal corneal diameter of <10 mm in infants or <11 mm in adults. Other presentations include shallow anterior chamber, corneal flattening, hyperopia etc. Px with microcornea can be highly hyperopic and can be associated with other systemic conditions, such as Ehlers-Danilo's, Nance-Horgan, Trisomy 13, 18, 21, Turner’s, Waadenburg’s and Weill-Marchesani.

Question 22

… is an uncommon congenital abnormalities which is inherited through … genes, therefore is more common in males. This abnormality is … in presentation. This is characterised by a … cornea with horizontal corneal diameter of … in infants or … in adults. Other presentations include … but normal IOP, …, … & astigmatism but …. They may also present with … due to zonular stretching. There may also be angle abnormalities causing …. Px with megalocornea can be associated with …, Alport’s, …’, …’ and osteogenesis imperfecta.

Answer 22

Megalocornea is an uncommon congenital abnormalities which is inherited through X-linked recessive genes, therefore is more common in males. This abnormality is bilateral in presentation. This is characterised by a clear cornea with horizontal corneal diameter of >12 mm in infants or >13 mm in adults. Other presentations include very deep anterior chamber but normal IOP, steep cornea, high myopia & astigmatism but normal VA. They may also present with lens subluxation due to zonular stretching. There may also be angle abnormalities causing secondary glaucoma. Px with megalocornea can be associated with albinism, Alport’s, Down’s, Marfan’s and osteogenesis imperfecta.

Question 23

Sclerocornea is a ..., congenital, but often ... condition. It is ... and usually bilateral. The cause of sclerocornea is .... Sclerocornea is characterised by the ... and ... of the periphery or .... It is often associated with ..., ..., anterior segment ..., ` …, … cataract, iris abnormalities and …. In severe cases, px may require …`, however there is poor prognosis.

Answer 23

Sclerocornea is a rare, congenital, but often asymmetric condition. It is non-progressive and usually bilateral. The cause of sclerocornea is unknown. Sclerocornea is characterised by the opacification and vascularisation of the periphery or the entire cornea. It is often associated with cornea plana, glaucoma, anterior segment dysgeneses, blue sclera, congenital cataract, iris abnormalities and microphthalmos. In severe cases, px may require penetrating keratoplasty, however there is poor prognosis.