Crystalline Lens B7

Question 1

Is there blood supply in the lens?

Answer 1

No blood supply

Question 2

The lens is a ____________ structure that is located posterior to the iris and pupil and anterior to the vitreous body

Answer 2

Biconvex

Question 3

Which curvature is steeper, anterior or posterior curvature?

Answer 3

Posterior curvature is far steeper (5-8 mm ROC)
Anterior curvature (8-14 mm ROC)

Question 4

Where are the poles?

Answer 4

at the center of the anterior and posterior curvature. Anterior and posterior poles

Question 5

At birth the lens diameter is _____.

As an adult the lens diameter is ____.

Answer 5

6.5 mm
10 mm
Lens diameter doesn’t increase significantly with age, but lens thickness increases 0.02 mm per year

Question 6

How much power does the lens have?

Answer 6

15-20 D of total 60 D
Power is reduced to +8 by age 40 (presbyopia)
reduced even further to +1 or +2 by 60

Question 7

The lens equator is only ____ away from the ciliary processes of the pars plicata

Answer 7

0.5mm

Question 8

What is the indent where the lens sits posteriorly?

Answer 8

Patellar fossa

Question 9

What is the ligament at the back of the lens connecting to the vitreous or posterior zonules?

Answer 9

Wieger’s ligament

Question 10

What is the space in the posterior part of the lens that is between the patellar fossa and the lens.

Answer 10

Berger’s space

Question 11

What are the 3 parts of the crystalline lens?

Answer 11

Elastic capsule
-thickest in the body (20 microns)
-in direct contact with anterior lens epithelium
Lens Epithelium
-anteriorly the capsule is secreted by anterior lens epithelium
-posteriorly there is no epithelium (3 microns thick)
Lens fibers
-secrete the posterior lens capsule

Question 12

How thick is the anterior lens capsule?

How bout the posterior lens capsule?

Answer 12

20 microns

3 microns

Question 13

Are there elastic fibers in the capsule?

Answer 13

NOOOOOO

Question 14

Anterior capsule _________ with age.

Answer 14

increases

1/3 larger by age 65

Question 15

What are the lens capsule functions?

Answer 15

Diffusion barrier

Makes lens Pliable for accommodation

Question 16

What layer of the lens do the zonules attach?

Answer 16

Zonular Lamella (outer most layer of lens)

Question 17

What kind of cells does the lens epithelium have?

Answer 17

MONOLAYER of CUBOIDAL cells
NO POSTERIOR EPITHELIUM
(epithelial cells proliferate through life, and stretch and become columnar in shape)

Question 18

The lens epithelium proliferates at _________________, at equator to form lens fibers. And secretes the lens ______.

Answer 18

Germanative zone

capsule

Question 19

_________________ is involved in the transport of substances from aqueous humor to lens interior.

Answer 19

Central anterior epithelium

Question 20

Is there epithelium on posterior side of lens?

Answer 20

NO!