Disorders of the Lens Flashcards

1
Q

Nuclear sclerosis (4)

A

1) compaction of fibers in lens center
2) detectable by 6-7 yrs in dogs & cats; 8-10 in horses
3) does not obstruct light/affect vision
4) looks like a lens within a lens

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2
Q

Lens function in light refraction (1)

A

1) component of eye’s focusing apparats

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3
Q

Lens function in accommodation (2)

A

1) active process of focusing on near objects
2) poorly developed in domestic species

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4
Q

Congenital Lens Disorders (6)

A

1) Aphakia (rare)
2) Microphakia (rare)
3) Spherophakia
4) Coloboma
5) Lenticonus
6) Vascular anomalies (most common)

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5
Q

Embryonic Vascular Anomalies of Lens (3)

A

1) Persistent pupillary membrane
2) persistent hyaloid artery
3) PHP/PHTVL

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6
Q

Cataracts (4)

A

1) light obstructing opacity of lens
2) very common lens disease
3) may result in significant vision deficit
4) many causes

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7
Q

Causes of cataracts in DOGS (3)

A

1) Heredity
2) old age
3) Metabolic

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8
Q

Cause of Cataracts in CATS & HORSES (1)

A

1) Uveitis

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9
Q

Cataract Classification

A

1) Etiology
2) age of onset
3) stage of progression
4) location

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10
Q

Cataract progression (1)

A

1) Predictability depends on etiology and age

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11
Q

Clinical stages of Cataracts (4)

A

1) Incipient: <15% of lens affected
2) immature: >15% of lens affected can still see tapetum reflection
3) mature: no tapetum reflection
4) hypermature: resorption of lens fibers, lens looks wrinkly

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12
Q

Consequences of Cataract (4)

A

1) vision loss
2) no effect on PLR or dazzle reflex
3) lens induced uveitis (hypermature)
4) may lead to secondary glaucoma or retinal detachment

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13
Q

Lens induced uveitis (4)

A

1) immune reaction to lens proteins
2) causes: cataract & lens rupture
3) topical corticosteroids
4) lens removal if lens is ruptured

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14
Q

Lens luxation (3)

A

1) dislocation of the lens
2) anterior or posterior
3) anterior most problematic

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15
Q

Clinical signs of lens luxation (4

A

1) blepharospasm/epiphora
2) red eye
3) cloudy eye
4) diminished vision

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16
Q

Primary lens luxation etiology (3)

A

1) hereditary zonule defect (potential to be bilateral
2) most commonly seen in dogs (terriers)
3) 3-7 years

17
Q

Secondary lens luxation etiology (4)

A

1) uveitis
2) hypermature cataract
3) senescence
4) trauma

18
Q

Lens luxation complication (4)

A

1) corneal edema
2) retinal detachment
3) Uveitis
4) corneal edema

19
Q

Management of anterior luxation (2)

A

1) may cause acute severe glaucoma EMERGENCY
2) surgical lens extraction or physical displacement of lens into back of eye

20
Q

Management of posterior luxation/subluxation (2)

A

1) trap lens in posterior segment
2) surgical removal

21
Q

Asteroid Hyalosis (4)

A

1) small white spherical bodies within vitreous
2) calcium-lipid composition
3) degenerative disorders
4) older dogs

22
Q

Syneresis (4)

A

1) Vitreous liquefacation
2) age related degenerative change or secondary to posterior segment inflammation
3) uncommon primary disorder
4) may predispose to retinal detachment