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Pathology > Cataract and glaucoma > Flashcards

Cataract and glaucoma Flashcards

1
Q

What refractive defect doesn nuclear cataract cause?

A

Increasing myopia

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2
Q

What cataract occur due to corticosteroid use?

A

Subcapsular

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3
Q

What are levels of cataract maturity

A

Immature
Mature - dense, white, obstructs red reflux
Hypermature - mature cataract ages and leaks water causing shrinkage of lens capsule
Morgagnian - cortical lens matter liquefies with inferior displacement of the nucleus in the bag

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4
Q

What is ageing of the lens?

A

LEvel of oxidation lower in age related cataract
In cataract extensive oxidation of lens protein

Gamma crystallins are synthesised less and beta crystallins increase

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5
Q

What happens in aged related cataract

A

Breakdown of antioxidant mechanisms of the lens, mainly reduced glutathione levels
Increased proteolytic activity
UV light absorbed by lens tryptophan - coverted to compounds that act as photosensitiser for free radical formation - free radical down regulates NA/K/ATPase - water influx

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6
Q

What are drug causes of cataract?

A

Coricosteroid - topical or systemic
Amiodarone
Aspirin
Chlorpromazine
Topical glaucoma medication - pilocarpine

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7
Q

What are systemic disease causes of cataract?

A

Diabetes mellitus
Myotonic dystrophy
Wilson’s disease
Atropic dermatitis
NF2

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8
Q

What are ocular causes of cataracts?

A

Uveitis
Myopia
AACG
Retinal dystrophy

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9
Q

What is the mechanism of diabetes induced cataract?

A

High glucose and galactose conc in aquodu lead to higher intracellular glucose in lens

Overwhelms anaerobic glycolysis pathway - prevents normal aldose reductarse inhibiton of polyol pathway

Upregulated polyol pathway and accumulation of polyols (Sorbitol ) in cells

This pulls water into cell

Aquaporin of MIP26 activatd - reduced ATP and glutathione - hence oxidative damage

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10
Q

What are the cellular changes that occur in cataract?

A

Loss of cell organisation
Formation of vacuoles within lens fibres

Water accumulation within the lens

Disruption of lens crystallin organisation and formation of lens protein aggregates

Accumulation of protein aggregates and chromophres - changes in colou from yellow to red to black

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11
Q

What are risk factors for POAG

A

Smoking
Diabetes
Hypertension
Hypercholestrolaemi
Myopia

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12
Q

What is the leading cause of irreversible blindness?

A

Glaucoma

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13
Q

what is the cause of high IOP

A

Abnormal resistance to outflow of the aqueous

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14
Q

What does high IOP result in ?

A

Pressure induced ischaemia of the capillary bed of the optic nerve
Direct mechanical pressure reducing axoplasmic flow in the axons passing through the lamina cribrosa

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15
Q

What nerve fibres are damaged in glaucoma?

A

Above or below the horizontal line on the temporal side of disc
Prelaminar optic nerve fibres

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16
Q

What may accompany high IOP

A

Occlusive disease
Poor perfusion of the posterior ciliary arteries resulting in ischaemic optic atrophy

Combination of poor perfusion and pressure induced ishcaemia causing prelaminar nerve fibre atrophy leads to enlargement of the optic nerve head in the vertical plane and field loss

17
Q

What place does the ONH elarge

A

Vertical

18
Q

What field loss may you get in POAG

A

Nasal step
Arcuate scotoma

19
Q

What are rikf actors for primary angle closure clausoma?

A

Hypermetropia
Following blunt trauma

20
Q

What happens in primary angle closure glaucoma?

A

Globe becomes smaller with age
Lens enlarges

Anterior surface of lens pushes the iris anteriorly causing the drainage angle to narrow

As pressure builds up behind the iris it forces the iris more peripherally towards the trabecular meshwork causing rise in pressure

21
Q

What can cause secondary open angle glaucoma?

A

Cells and protein in uveitis
Haemorrhage in trauma
Tumour cell infiltration
Lens matter or macrophages containing lens matter

22
Q

What is phacolytic gluacoma

A

Lens matter or macrophages containing lens matter blocking angle

23
Q

What are causes of secondary angle closure glaucoma

A

Tumours of the eye e.g. melanoma forcing the lens forward
Anterior or posterior synaechiae in uveitis - adhesion between iris and trabecular meshwork (anterior) and iris and lens (posterior) produces obstruction of flow at the pupil (iris bombe)

Rubeotic glaucoma caused by fibrovascular proliferation in the angle due to retinal ischaemia

24
Q

What is iris bombe?

A

Adhesion between iris and lens (posterior) produces obstruction of flow at the pupil

25
Q

What is rubeotic glaucoma

A

Fibrovascular proliferation in the angle due to retinal ischaemia causes obstruction

Pathology (15 decks)

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