Dzs of the lens (Whitley) Flashcards
1
Q
Normal lense placement
responsibilities
A
- behind iris, in front of vitreous
- patella fossa
- held in place by zonules
- responsibilities
- refraction
- accomodation
2
Q
Lens anatomy
A
- Capsule
- basement membrane surrounding lens
- Anterior epithelium
- Lens fibers
- interdigitating layers
- form Y sutures
- upright anterior Y
- inverted postierior Y
- Cortex
- Nucleus
3
Q
Clinical anatomy of lens
A
- second most imp refractive structure
- cornea is number 1
- transparent
- no innervation
- no vascular structures
- lens epithelium
- present at equator
- lines anterior cortex
- three major regions
- cortex
- nucleus
- capsule
4
Q
Lens formation
embryology
A
- basement membrane becomes lens capsule
- anterior lense capsule get thicker and thicker
- posterior doesn’t
5
Q
Lens fibers
A
- Fibers continuously produced
- compacted towards center of lens
- lens becomes more dens/sclerotic with age
- nuclear sclerosis
- central nucleus gets hard
6
Q
Dzs of lens
A
- Cataract
- opacity of lens or lens capsule
- Subluxation
- luxation
- congenital abnormalities
- microphakia
- aphakia
- lenticonus
7
Q
Nuclear sclerosis vs cataract
A
- Nuclear sclerosis
- lens within a lens
- bilateral
- symmetric
- center of lens
- doesn’t interfere with fundus exam
- can visualize tapetal reflex through sclerosis
- no clinical interference with vision
8
Q
A
- Left: Cataract
- Right: Nuclear sclerosis
9
Q
A
Nuclear Sclerosis and Cataract
10
Q
Classifying cataracts
Location
A
- Structure of lens
- capsular
- subcapsular
- cortical
- nuclear
- Direction
- anterior
- posterior
- equatorial
- polar
- axial
11
Q
Leukocoria
A
- White pupil
- usually means a cataract
12
Q
Cataract classification
Schemes
A
- stage of development
- maturity
- size
- location of opacity within lens
- age of development of cataract
- consistency
- fluid
- soft
- hard
- sticky
- etiology
13
Q
Cataract
stages of maturity (amount of lens involved)
A
- Incipient
- ,15% total lens volume
- Immature
- early
- late
- 16-99%
- Mature
- 100% lense is cataractous
- Hypermature
- lens resorption
- lens cortex liquifies
- may result in return of sight in young dogs
- morgagnian
- lens nucleus sinks ventrally in liquified cortex
- all cortical material has been resorbed leaving behind nucleus
- lens resorption
14
Q
Incipient cataract
A
- early focal opacity of lens
- appearance
- punctate
- linear “spoke-like”
- vacuoles
- vision usually not affected
15
Q
Immature cataract
A
- Opacity is more expansive than incipient
- reduced transparency
- some tapedal reflection remaines
- decreased vision
- optimum time to surgically remove
