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OD1 Semester 2 - Integrated Ophthalmic Sciences and Preclinical Optometry > Oc. Manifestations - Week 4 > Flashcards

Oc. Manifestations - Week 4 Flashcards

1
Q

Prevalence of ocular congenital disorders in Aus?

A

Rare: less than 1.5% of congenital affect the eye

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

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2
Q

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

A
  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

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3
Q

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

A
  • Tuberous Sclerosis (TF)
  • Neurofibromatosis (NF): types 1 and 2
  • Sturge-Weber syndrome [important one]
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4
Q

Can Phakomatoses cause tumours?

A

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

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5
Q

Can Phakomatoses be sporadic or are they only inherited?

A

They can be both sporadic or inherited

  • but they are mostly inherited
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6
Q

Which types of congenital eye disorders are ALWAYS acquired?

A

Infections and Drug embryopathy

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7
Q

Define Sturge-Weber syndrome:

A

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)

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8
Q

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

A
  1. Skin and/or
  2. Eye and/or
  3. CNS
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9
Q

How can Sturge-Weber affect the skin?

A

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

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10
Q

How can sturge-Weber affect the eye?

A

Choroidal hemangioma, glaucoma

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11
Q

Define hemangioma

A

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

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12
Q

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

A

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

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13
Q

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

A

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

Known as Formative Stage 1

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14
Q

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

A

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

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15
Q

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

A

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

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

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16
Q

What is a port wine stain (PWS)?

A

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

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17
Q

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

A

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

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18
Q

Define Angioma

A

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

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19
Q

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

A

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

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20
Q

Where can angioma occur in Sturge-Weber?

A
  • lymphatic (lymphangioma)
  • vessel walls (hemangioma)
  • tissues surrounding the vessels (telangiectasia, ectasia)
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21
Q

Define Ectasia

A

dilation or distention of a tubular structure

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22
Q

Describe the histopathology of lid angiomatosis

A
  • many capillaries
  • thickened vascular endothelial cells

tumour is usually benign

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23
Q

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

A

Lead to congenital glaucoma

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24
Q

List eye-related common pathology for Patau’s syndrome

A
  • coloboma: often assoc. with undifferentiated mesenchyme
  • microphthalmos
  • glaucoma
  • retinal dysplasia
  • corneal dysgenesis
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25
Q

Describe optic nerve coloboma

A

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

26
Q

Inheritance pattern for coloboma?

A

Autosomal dominant/recessive or X-linked

27
Q

ocular co-morbidities for coloboma?

A
  • gluacoma
  • micropthalmia
  • retinal dysplasia
  • posterior staphyloma
  • heterochromia
  • nystagmus
28
Q

Give an example of infectious embryopathy

A

Congenital Rubella Infection

29
Q

When does congenital rubella infection occur?

A

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

30
Q

How can rubella cause a congenital cataract?

A

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

31
Q

How does rubella virus enter the lens?

A

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

32
Q

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

A

Because during development, the lens has a vascular supply

33
Q

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

A

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

34
Q

How long can rubella virus remain in the lens?

A

up to 3 years

35
Q

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

A

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

36
Q

Describe the histopathology of Rubella Virus

A
  • 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
37
Q

Name an example of Drug Embryopathy

A

Foetal Alcohol Syndrome (FAS)

38
Q

What causes Foetal Alcohol Syndrome (FAS)?

A

Excessive maternal alcohol consumption during pregnancy

39
Q

Ocular effects of FAS?

A
  • narrow palpebral fissure
  • ptosis
  • STRAB
  • microcornea
  • cloudy cornea
  • optic nerve hypoplasia (sectoral, total) etc.

Nice cats meow, purr or scratch

40
Q

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

A

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

41
Q

What proportion of congenital cataracts in victoria are hereditary?

A

~25%

42
Q

In what ways/locations can congenital cataracts manifest?

A
  • anterior
  • posterior polar
  • sutural
  • nuclear
43
Q

Do all cataracts have a profound effect on vision?

A

no

44
Q

Polar cataracts can be either ____ or ___

A

cortical or subcapsular

45
Q

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

A

Nuclear cataract

46
Q

Which cataract can be inheritied by y-crystallin gene mutations

A

Nuclear cataract

47
Q

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

A

Polar cataract

48
Q

Which cataract occurs later in development? Why?

A

Polar cataract - due to incomplete regression of surrounding tissue

(i.e. hyaloid vasculature regresses at beginning of 4th month)

49
Q

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

A

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

50
Q

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

A

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

51
Q

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

A

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

52
Q

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

A

Has a more white-ish appearance

- this is due to the atrophy allowing for greater light reflection from the collagen of the lamina cribrosa

53
Q

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

A

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

54
Q

Describe the histopathology of optic nerve atrophy

A
  • 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)
55
Q

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

A
  1. Ascending (to CNS; e.g. glaucoma)

2. Descending (from CNS; e.g. hydrocephalus)

56
Q

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

A

Genes that affect mitochondrial metabolism in retinal ganglion cell axons

57
Q

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

A

mutation of mitochondrial DNA

58
Q

When does myelination of nerve fibres start (embryology)?

A

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

59
Q

Where does myelin growth usually stop?

A

At the lamina

60
Q

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

A

Trisomy 21

61
Q

What mediates myelin growth?

A

Oligodendrocytes

62
Q

How does myelination affect the thickness of the RNFL

A

Makes it thicker

OD1 Semester 2 - Integrated Ophthalmic Sciences and Preclinical Optometry (49 decks)

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