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OD1 Semester 2 - Integrated Ophthalmic Sciences and Preclinical Optometry > Connective Tissue - Week 4 > Flashcards

Connective Tissue - Week 4 Flashcards

1
Q

Provide 2 examples of heritable C.T (conn tissue) disorders:

A

Stickler syndrome - vitreous changes

Marfan syndrome - ectopic lens

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2
Q

Provide 1 example of an autoimmune CT disorder:

A

Scleritis - sclera like necrosis

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3
Q

Which CT disorder can be characterised by scleral thinning?

A

High myopia

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4
Q

What can the presence of abnormal fibrillar collagen molecules cause? (3)

A

1) delay fibril formation
2) reduce total amount of collagen incorporated into the fibrils
3) alter the morphology of the fibrils

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5
Q

How may alterations in amino acid content or spacing affect collagen? (3 things affected)

A

Affect collagen:

  • structure
  • stability
  • biological performance
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6
Q

Hydroxyproline is a major component of the protein collagen. What is it important for?

A

The sharp twisting of the collagen helix, which is temperature dependent

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7
Q

What results from the absence of Hydroxyproline?

A

Reduced Thermal stability of collagen triple helix

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8
Q

Compare the % of helix content between normal collagen and collagen without Hydroxyproline at 40 degrees celsius

A

At 40 degrees,
Normal collagen = 100% helix content
Without Hydroxyproline = ~10%

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9
Q

What do changes in collagen ECM components affect? How can these changes occur?

A

Collagen structure

Can be genetic or environmentally derived

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10
Q

What can mutation in a constituent single protein molecule do?

A

Has a profound effect on molecular complex and tissues

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11
Q

What type of collagen interaction is important for regulating fibril diameter?

A

Heterotypic type I/V interactions

type one/five

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12
Q

List the general issues that can have profound effects on collagen structure/function (5)

A
  • presence of abnormal molecules
  • altered amino acid spacing or content
  • changes in ECM matrix components
  • mutation in constituent single protein molecule
  • altered expression in protein associated macromolecules
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13
Q

List the 4 ways the immune system can respond:

A

1/ Defend successfully
2/ Autoimmunity - fail to distinguish self vs non-self
3/ Hypersensitivity - excess response
4/ immune deficiency - inadequate/absent response

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14
Q

List the 5 main components of the immune system response

A
  • recognition
  • specificity
  • antibody production
  • cell-mediated reactions
  • memory
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15
Q

What is Sjögren’s syndrome and what occurs in it?

A

Autoimmune disease of connective tissue

Involves t-cell infiltration of lacrimal gland

leads to inability to secrete saliva or tears

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16
Q

How is Stickler’s syndrome inherited?

A

Autosomal dominant (and newly identified recessive form)

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17
Q

Define arhtro-opthalmopathy. List a CT disorder that could be described this way

A
  • an association of degenerative joint disease and eye disease
  • Stickler Syndrome
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18
Q

What are the 5 subgroups of ocular and systemic manifestations that result from Stickler Syndrome?

A 
Type 1 - ocular + systemic
Type 2 - ocular + systemic
Type 3 - systemic only
Type 4 - ocular + systemic; recessive
(Type 5) - ocular only (similar to type 1 but w/o systemic)
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19
Q

What are the functional ocular consequences of Stickler Syndrome?

A

Ocular:

  • vitreous abnormalities
  • retinal degeneration/tears/breaks
  • cataracts
  • glaucoma (open angle)
  • high myopia
20
Q

What are the functional systemic consequences of Stickler Syndrome?

A

Systemic:

  • skull, joint abnormalities
  • hearing loss
  • cleft palate
  • heart problems
21
Q

What are the identified mutations in Stickler syndrome types (4)?

A

Type 1 - COL2A1
Type 2 - COL11A1
Type 3 - COL11A2
Recessive - COL9A1 and COL9A2

22
Q

What local clinical manifestations in the eye arise from the first 4 types of Stickler Syndrome?

A

Type 1 - sometimes vitreous manifestations only, sheet-like vitreous opacities or vitreous hypoplasia
Type 2 - Bead-like vitreous opacities or vitreous hypoplasisa
Type 3 - No ocular phenotype
(Type 4) Recessive - premature vitreous degen.

23
Q

What type of anomalies are the following types of Stickler Syndrome: 1, 2 and 4?

A

Type 1 - membranous vitreal anomaly
Type 2 - beaded vitreal anomaly
Type 4 - premature vitreous degen.

24
Q

Which type of Stickler Syndrome presents with a loss of collagen type IX? Is this also a feature of age-related vitreous changes?

A

Type 4, yes

25
Q

T/F: Vitreoretinal adhesions are a feature of age-related vitreous changes but NOT Stickler type 4

A

False. It is a feature of both

26
Q

What mutations causes Marfan syndrome?

A 
Mutation in fibrillin-1 gene (80% of cases)
new mutations (25% of cases)
27
Q

Describe the pattern of inheritance for Marfan Syndrome

A

Autosomal dominant with high penetrance

28
Q

Explain the major ocular complication of Marfan Syndrome.

A

‘Ectopia Lentis’ - i.e. the lens is displaced

29
Q

Clinical pathology of Marfan syndrome (4)

A
  • lens displaced
  • flat cornea
  • increased axial length of globe
  • hypoplastic iris or hypoplastic cil. muscle causing decreased miosis (i.e. underdevelopment of cil. mus./iris)
30
Q

In Marfan syndrome, where does lens displacement occur?

A

Usually superiotemporally

31
Q

List the functional consequences of Scleritis

A

In severe cases:

  • thickened sclera
  • intraocular sequelae incl. retinal detachment
  • gluacoma

In very severe cases:

  • necrosis + scleral perforation
  • intraocular sequelae incl. infection
32
Q

T/F: The fibres MUST have a problem/mutation in gene encoding alpha sub units to cause CT disorder

A

False

33
Q

What is Lumican?

A

A small proteoglycan present in the corneal stroma

34
Q

What can a lack of lumican result in?

A
  • larger fibril diameters
  • disorganised fibril spacing
  • corneal clouding
35
Q

What is a frequent comorbidity of Scleritis? And is it painful? How long until it resolves

A

Episcleritis. Causes mild discomfort without pain. Usually resolves within 2 weeks

36
Q

How does impaired fibrillin-1 affect the lens zonules?

A

Weakens them

37
Q

List the 4 different presentations of sceleritis:

A
  1. Acute
  2. Nodular
  3. Necrotising with inflammation
  4. Necrotising without inflammation
38
Q

Is high myopia considered a CT disorder?

A

Yes

39
Q

How many diopters is high myopia?

A

More than 6

40
Q

How does high myopia affect axial length?

A

Increased axial length

41
Q

How does high myopia affect risk of chorioretinal degeneration and retinal detachment?

A

Increases risk for both

42
Q

What happens to the sclera in high myopia? Where does this happen?

A

Sclera thins dramatically at the posterior pole

43
Q

Name a possible genetic explanation for high myopia?

A

Mutation in SCO2 gene

44
Q

What is the role of the SCO2 gene?

A

Helps metabolise copper and thus regulates O2 in the eye

45
Q

Explain the functional significance of high myopia? (4)

A
  • reduced tensile strength of sclera
  • major effect at posterior pole
  • increased rate of eye growth under normal IOP
  • feature of young eyes and myopic eyes

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

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