Oc. Manifestations - Week 4

Question 1

Prevalence of ocular congenital disorders in Aus?

Answer 1

Rare: less than 1.5% of congenital affect the eye

Male: 0.06%, female: 0.04% total: 0.05%

Question 2

Describe the 5 types of congenital disorders which affect the eye.

Answer 2

1. Phakomatoses:
   - nuero-cutaneous syndromes of ectodermal origin
   - most common manifestation in children = skin lesions
2. Chromosomal:
   - Chrom. or minor gene sequence anomalies
3. Infections:
   - infectious agents affect foetal development
4. Drug embryopathy:
   - maternal drug use affect foetal development

Other:
- cause not determined

Question 3

List 3 of the most common Phakomatoses/neuro-cutaneous disorders [not from slides, from own study]

Answer 3

• Tuberous Sclerosis (TF)
• Neurofibromatosis (NF): types 1 and 2
• Sturge-Weber syndrome [important one]

Question 4

Can Phakomatoses cause tumours?

Answer 4

Yes. Can cause benign congenital tumours (I.e birthmarks)

Question 5

Can Phakomatoses be sporadic or are they only inherited?

Answer 5

They can be both sporadic or inherited

• but they are mostly inherited

Question 6

Which types of congenital eye disorders are ALWAYS acquired?

Answer 6

Infections and Drug embryopathy

Question 7

Define Sturge-Weber syndrome:

Answer 7

A sporadic congenital neuro-cutaneous disorder characterised by a port-wine stain affecting the skin in the distribution of the ophthalmic branch of the trigeminal nerve (CNV)

Question 8

What 3 parts of the body can be affected by Sturge-Weber’s syndrome?

Answer 8

1. Skin and/or
2. Eye and/or
3. CNS

Question 9

How can Sturge-Weber affect the skin?

Answer 9

Port wine stain (PWS) - capillary hemangioma, cutaneous naevi

Question 10

How can sturge-Weber affect the eye?

Answer 10

Choroidal hemangioma, glaucoma

Question 11

Define hemangioma

Answer 11

A benign tumour of blood vessels, often forming a red birth mark

Question 12

Briefly describe the process of eye embryology (day 19 to day 36)

Answer 12

Day 19: Neural plate forms neural groove
Day 20: Neural folds grow towards each other to form neural tube
3.5wk/~Day 24: Neural tube closes
Day 27: Optic vesicle outgrowth from each side of forebrain
Day 27: Surface ectoderm pushes into optic vesicles and becomes LENS PLACODE, also optic cup forms
Day 36: Lens placode gets suspended from neural ectoderm into eye

Question 13

How do optic vesicles form, and when do they form? (embryology). What is this stage of embryogenesis known as?

Answer 13

Day 25: Indentations (optic pits) form in neural tube and then expand to form sac-shaped extensions (optic vesicles)

Known as Formative Stage 1

Question 14

How does embryology form fissures for the hyaloid artery and vein to pass through?

Answer 14

At day 35 (Formative Stage 3): Closure of optic stalks form a cleft called fetal (choroidal) fissure which the hyaloid artery and vein pass through

Question 15

Are facial port wine stains always indicative of Sturge-Weber’s syndrome?

Answer 15

No. Commonly, facial PWS is not indicative of Sturge-Weber’s.

However, if you have Sturge-Weber’s, you will have a PWS

Question 16

What is a port wine stain (PWS)?

Answer 16

It’s a discolouration of the skin caused by vascular anomaly, usually on the face

Question 17

Which location of Port-wine Stain is associated with increased risk of Glaucoma? Where would this Glaucoma most likely develop?

Answer 17

When PWS is distributed along the upper trigeminal nerve on the face (greatest risk if affecting upper eyelid)
- 1/3rd of these patients develop glaucoma

Glaucoma is most likely to be ipsilateral to the PWS

Question 18

Define Angioma

Answer 18

An abnormal growth/tumour caused by the dilation or formation of new blood vessels

Question 19

What causes the port wine stain (PWS) in Sturge-Weber?

Answer 19

is caused by excess capillaries just below the skin’s surface, or from capillary hemangioma (benign tumour of blood vessels)

Question 20

Where can angioma occur in Sturge-Weber?

Answer 20

• lymphatic (lymphangioma)
• vessel walls (hemangioma)
• tissues surrounding the vessels (telangiectasia, ectasia)

Question 21

Define Ectasia

Answer 21

dilation or distention of a tubular structure

Question 22

Describe the histopathology of lid angiomatosis

Answer 22

• many capillaries
• thickened vascular endothelial cells

tumour is usually benign

Question 23

SW syndrome: What happens if there is a anomalous vascularity at the canal of schlemm?

Answer 23

Lead to congenital glaucoma

Question 24

List eye-related common pathology for Patau’s syndrome

Answer 24

• coloboma: often assoc. with undifferentiated mesenchyme
• microphthalmos
• glaucoma
• retinal dysplasia
• corneal dysgenesis

Question 25

Describe optic nerve coloboma

Answer 25

optic nerve coloboma shows incomplete retinal/choroidal closure and condensation of the scleral mesenchyme over the gap - forms a staphyloma like structure in response, parts of the forming optic nerve may prolapse into space

Question 26

Inheritance pattern for coloboma?

Answer 26

Autosomal dominant/recessive or X-linked

Question 27

ocular co-morbidities for coloboma?

Answer 27

- gluacoma - micropthalmia - retinal dysplasia - posterior staphyloma - heterochromia - nystagmus

Question 28

Give an example of infectious embryopathy

Answer 28

Congenital Rubella Infection

Question 29

When does congenital rubella infection occur?

Answer 29

When the virus crosses the placenta into the embryo - most likely in first trimester

Question 30

How can rubella cause a congenital cataract?

Answer 30

Rubella virus gets into the lens during development before the capsule has formed and destroys the embryonic cells

Question 31

How does rubella virus enter the lens?

Answer 31

Through the blood supply, because the lens has no barrier to blood circulation during early development

Question 32

Why is there no barrier b/w the lens and blood circulation during early development?

Answer 32

Because during development, the lens has a vascular supply

Question 33

True or False: Fibre cells in rubella cataract don't regenerate

Answer 33

False. New fibre cells are generated to replace space left by destroyed embryonic lens cells

Question 34

How long can rubella virus remain in the lens?

Answer 34

up to 3 years

Question 35

What is the risk of surgery for people with Rubella Virus?

Answer 35

Surgery may release live rubella virus and cause endophthalmitis or cataract later on

Question 36

Describe the histopathology of Rubella Virus

Answer 36

- patchy atrophy and compensatory RPE hypertrophy during retinal development (outer retina becomes necrotic) - characterisitic "salt and pepper" fundus - due to variable density of melanocytes in RPE and choroid

Question 37

Name an example of Drug Embryopathy

Answer 37

Foetal Alcohol Syndrome (FAS)

Question 38

What causes Foetal Alcohol Syndrome (FAS)?

Answer 38

Excessive maternal alcohol consumption during pregnancy

Question 39

Ocular effects of FAS?

Answer 39

- narrow palpebral fissure - ptosis - STRAB - microcornea - cloudy cornea - optic nerve hypoplasia (sectoral, total) etc. *Nice cats meow, purr or scratch*

Question 40

What colour does the cornea appear as in FAS? Why?

Answer 40

Blue. Due to disrupted corneal collagen fibre bundles, which cause light scatter

Question 41

What proportion of congenital cataracts in victoria are hereditary?

Answer 41

~25%

Question 42

In what ways/locations can congenital cataracts manifest?

Answer 42

- anterior - posterior polar - sutural - nuclear

Question 43

Do all cataracts have a profound effect on vision?

Answer 43

no

Question 44

Polar cataracts can be either ____ or ___

Answer 44

cortical or subcapsular

Question 45

Which cataract manifestation is more likely to be assoc. with early lens embrologic disorder?

Answer 45

Nuclear cataract

Question 46

Which cataract can be inheritied by y-crystallin gene mutations

Answer 46

Nuclear cataract

Question 47

Which cataract is usually caused by an anomaly in the neighboring tissue?

Answer 47

Polar cataract

Question 48

Which cataract occurs later in development? Why?

Answer 48

Polar cataract - due to incomplete regression of surrounding tissue (i.e. hyaloid vasculature regresses at beginning of 4th month)

Question 49

What is a Mittendorf dot? Which cataract manifestation does it appear in?

Answer 49

Is a posterior polar opacity assoc. with a remnant hyaloid artery. Occurs in polar cataracts

Question 50

How can abnormal proliferation of a vitreal substance cause polar cataract?

Answer 50

is assoc. with incomplete atrophy of the vasculosum lentis, leaving a hyaloid remnant that can cause a polar cataract

Question 51

What is the effect of the remnant hyaloid (in relation to polar cataract)?

Answer 51

remnant hyaloid affects posterior cortical metabolism --> lens fibre necrosis --> degeneration of posterior subcapsular cortex

Question 52

How does atrophy of the optic nerve cells affect the appearance of the optic nerve head/disc in ophthalmoscopy?

Answer 52

Has a more white-ish appearance | - this is due to the atrophy allowing for greater light reflection from the collagen of the lamina cribrosa

Question 53

How does loss of optic nerve fibres affect the size of the optic nerve?

Answer 53

It shrinks the optic nerve from the meninges leaving an abnormally large sub-arachnoid space

Question 54

Describe the histopathology of optic nerve atrophy

Answer 54

- loss of ganglion cells reduces the bulk of the Optic nerve head: causing increased sub-arachnoid space - Increased thickness of pial septa - astrocytic gliosis - thinned retinal Nerve Fibre Layer (RNFL)

Question 55

In what 2 ways may acquired optic nerve atrophy travel from it's lesion (based on lesion position)?

Answer 55

1. Ascending (to CNS; e.g. glaucoma) | 2. Descending (from CNS; e.g. hydrocephalus)

Question 56

What sort of genes are often implicated in inherited optic nerve atrophy?

Answer 56

Genes that affect mitochondrial metabolism in retinal ganglion cell axons

Question 57

What is the cause of Leber's Hereditary Optic Neuropathy (LHON)?

Answer 57

mutation of mitochondrial DNA

Question 58

When does myelination of nerve fibres start (embryology)?

Answer 58

Myelination starts once fibres reach LGN (~23 weeks of gestation) - reaches lamina cribrosa (1-3 months post-natal)

Question 59

Where does myelin growth usually stop?

Answer 59

At the lamina

Question 60

What genetic condition is associated with abnormal extra myelination growth beyond it's normal stopping point?

Answer 60

Trisomy 21

Question 61

What mediates myelin growth?

Answer 61

Oligodendrocytes

Question 62

How does myelination affect the thickness of the RNFL

Answer 62

Makes it thicker