Lens

Question 1

What proteins are present in the lens

Answer 1

Crystallins - heat shock protein

Stabilise proteins that are partially unfolded - rpeventing then from aggregating

Question 2

How doers the lens grow?

Answer 2

ADding new fibre layers to outer surface
These fibres elongate extending their apical and basal ends towards the sutures.
At the sutures the cells meet a fibre cell coming form the opposite side of the lens.
The two fibres join and detach from the posterior capsule.
The fibres then lose their organelles

Question 3

What is anterior radius of curvature of lens? Posterior

Answer 3

Anterior 10mm
Posterior 6mm

Question 4

What is RI of cortex? Core?

Answer 4

1.386-1.406

Question 5

What is the near triad?

Answer 5

Accommodation, convergence, pupillary constriction

This si a synkinesis - no component depends on the other two

Question 6

What is the process of accommodation?

Answer 6

Circular ciliary muscle contracts, decreasing the tension in the zonular fibres
Allows lens capsue to contract and make lens more globular - more powerful
Anterior pole moves anteirorly and the axial width increases.
Equatorial diameter decreases

Question 7

What is faster pupillary light or accommodation response

Answer 7

Light

Question 8

Describe the lens capsule

Answer 8

Capsule of the anterior and posteiror poles slightly thinner than the equatorial capsule

Elastic and changes in shape occur becaue of increased pressure within the lens in unaccommodated state

Question 9

Where do zonular fibres arise and extend?

Answer 9

Arise from ciliary body
Pass from ciliary processes to lens
- attache to anterior and posterior lens capsule rather than the equator

Some zonular fibres form a meshwork across the cilliary body or extend from the pars plana to the vitreous body to form vitreous base

Question 10

What type of muscle is the ciliary msucle?

Answer 10

Smooth muscle

Predominantly longitudinal fibres that bend arteriorly to form a circle

Question 11

What happens to trabecular outflow when ciliary muscles are stimulated by muscarinic agonists

Answer 11

ciliary muscle produce accommodation
Pulls choroid anteriorly - increased traction on trabecular meshwork fibres via scleral spur aids aqueous outflow

Question 12

When does accommodation begin to develop? When is it well developed?

Answer 12

2 months

8 months

Question 13

What is the accomodative power of a 2 year old? 20 year old? 60 year old?

Answer 13

2 - 20D
20 - 10D
60 - 0D

Question 14

what happens in Adie’s pupil?

Answer 14

Damage to ciliary ganglion causes loss of accommodation and blurring of vision