LENS Flashcards
1
Q
LENS
A
- transparent biconvex structure
- attached to ciliary body by zonular fibres (suspensory ligament)
2
Q
LENS LOCATION
A
- behind iris + pupil
- in front of vitreous body
3
Q
TOTAL EYE DIOPTRIC POWER
A
58D
4
Q
LENS DIOPTRIC POWER
A
15D (can change)
5
Q
ACCOMMODATION
A
15-16D at birth
8D at 40
1-2D at 60
6
Q
ANTERIOR + POSTERIOR POLES
A
CENTRE POINTS ON ANT. + POST. SURFACES
7
Q
AXIS OF LENS
A
LINE JOINING POLES
8
Q
EQUATOR
A
MARGINAL CIRCUMFERENCE
9
Q
STRUCTURE OF LENS
A
- capsule
- epithelial layer
- stroma
10
Q
LENS CAPSULE
A
- elastic basal membrane
- envelopes the lens
- elastic nature allows accommodation
11
Q
LENS EPITHELIAL LAYER
A
- cuboidal cells below capsule on ant. surface
- at equator cells elongate + form columnar cells - transform into lens fibres
12
Q
WHERE IS MITOTIC ACTIVITY GREATEST IN LENS?
A
AT EQUATOR
13
Q
STROMA LENS
A
- made up of lens fibres
- makes up bulk of lens
- fibres form from epithelial cells in germinal zone (at equator)
14
Q
WHAT KEEPS LENS FIBRES IN PLACE?
A
BALL + SOCKET JOINTS
15
Q
LENS FIBRES FROM SAME LAYER JOIN AT?
A
SUTURES
