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VMS 2006 > Eye pathology IV- lens and the Retina > Flashcards

Eye pathology IV- lens and the Retina Flashcards

1
Q

What is the purpose of the lens?

A

Refract and focus light onto the retina

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2
Q

What is the main structure of the lens?

A
  • avascular
  • contains aqueous humour to transport nutrients and waste
  • only the lens epithelium is present- cells migrate inwards and transition to lens fibres
  • Zonular fibres extend from the ciliary body
  • pressure from the vitreous holds the lens in place

contains epithelial cells

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3
Q

What is ectopia lentis?

A

Displacement of the lens

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4
Q

What is cataracts?

A

opacity of the lens

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5
Q

What is neoplasia of the lens called?

A

Feline post-traumatic ocular sarcoma

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6
Q

What are the two sequelae for ectopia lentis?

A
  • Cataract
  • Glaucoma
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7
Q

What is a secondary cause of ectopia lentis?

A

Glaucoma- increased pressure causes the lens to move

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8
Q

What are the broad causes of cataracts?

A
  • Diabetes
  • Irradiation
  • Glaucoma
  • Toxins
  • Uveitis
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9
Q

What is the retina?

A
  • Neural tunic
  • Optic nerve
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10
Q

What cells in the retina connect directly to the optic nerve

A

Ganglion cells

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11
Q

What is a coloboma?

A

Failure of complete fusion of the optic fissure

cyst-liek outpouching of dysplastic neuroectoderm

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12
Q

What is a collie eye anomaly?

A

Recessively inherited mutation in NHEJ1 gene
in Collies, Shetland sheepdogs, Australian
shepherds + others

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13
Q

What is the basic pathogenesis of glaucoma?

A
  • decreased aqueous drainage-> IOP increase
  • axon damage at the lamoina cribosa
  • causes inner retinal atrophy (ganglion cells)
  • vascular comprimise
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14
Q

What ususally causes primary glaucoma?

A
  • angle malformations
  • primary open angle glaucoma
  • decreased outflow capacity of morphologically normal angle
  • humans, dogs, cats
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15
Q

What usually causes secondary glaucoma?

A
  • Synechiae (neovascular glaucoma)
  • occlusion of the angle- by cells (debris, haemorrhage etc.)
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16
Q

What are the two degrees of ectopia lentis?

A
  • Subluxation (partial)
  • Luxation (complete)
17
Q

What is incipient cataracts?

A

Less than 15% damage

18
Q

What is immature cataracts?

A

More than 15% damage

19
Q

What is mature cataracts?

A

complete obstruction of the lens

20
Q

What is hypermature cataracts?

A

lens dissolves/ lens shrinkage

21
Q

How does diabetes affect cataracts?

A
  1. Glucolse is the energy source for the lens fibres via the glycolytic pathway
  2. The rate limiting step for this breakdown is hexokinase
  3. when hexokinase is saturated in times of increased glucose there is an alternative pathway- sorbitol pathway
  4. breakdown of sorbitol is low so it accumulates in the lens and causes cell swelling/ rupture
22
Q

What is FPTOS?

A

Feline post-traumatic ocular sarcoma

23
Q

What is retinal detachment

A

Retinal pigmented epithelium separates from the neurosensory layers at the level of photoreceptors

23
Q

What is a subluxation ectopia lentis

A

partial dislocation of the lens

24
Q

What is a luxation ectopia lentis

A

complete dislocation of the lens

25
Q

What are the two main primary causes of ectopia lentis?

A
  • Abnormal or insufficient zonular fibres
  • ADAMTS17 gene mutation- terriors are predisposed
26
Q

What are the sequelae to ectopia lentis?

A
  • Cataract
  • Glaucoma
27
Q

What are the 4 classifications of lens involvement for cataracts?

A
  • Incipient <15%
  • Immature >15%
  • Mature (complete)
  • hypermature (lens shrinkage)
28
Q

What can cause lens neoplasia?

A
  • Feline post-traumatic ocular sarcoma
  • Lens epithelium cell of origin (expresses vimentin)
  • often occurs years after the initial trauma
29
Q

What is the gross pathology of lens neoplasia?

A
  • Often fills the globe
  • characteristically lines the choroid
  • lens may be collapsed
  • pale tan, nodular to multinodular
30
Q

Where do the axons of the retinal ganglion cells exit the globe?

A

they exit via perforations in the sclera known as the lamina cribrosa

31
Q

What are the components of collie eye anomaly?

A
  • Choroidal hypoplasia
  • Retinal detachment
  • Retinal dysplasia
  • posterior segment haemorrhage
32
Q

What is retinal detachment?

A
  • Retinal pigmented epithelium separates from neurosensory layers at the level of photoreceptors
33
Q

What are the histiological indicators of true detachment?

A
  • Exudate between separated layers
  • Photoreceptor outer segment loss
  • Hypertrophy of the RPE
34
Q

What is SARDS?

A
  • Degenerative condition, assumed to be heritable
  • thinning or complete loss of the photoreceptor
  • invariably leads to blindness
35
Q

What are the clinical signs of glaucoma?

A
  • Red eye
  • Mydriasis (dilated pupil)
  • Buphthalmia (Big eye)
  • Cornea oedema/ Keratitis
  • Endothelial dysfunction and/or exposure keratitis

VMS 2006 (25 decks)

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