Lecture 12

Question 1

what is age related macro degeneration?

Answer 1

blurred vision in the centre of the visual field and loss of colour

Question 2

what are the 4 main affects of AMD?

Answer 2

• Slow recovery of visual function after exposure to bright light
• Trouble discerning colours - a loss in contrast sensitivity
• Visual acuity decreases
• blurred vision

Question 3

what are the 2 forms of AMD?

Answer 3

1) Wet – new blood vessels grown within diseased retinal tissue and leak and damage the retina
2) Dry – degeneration occurring in the retina - little or no haemorrhaging

Question 4

what are early predictive signs of both types of AMD?

Answer 4

• Common characteristic of both is fatty deposits on the retina (drusen)
• Builds up between bruch’s membrane and retinal pigment epithelium of the eye

Question 5

what are the rods and cones for in the eye?

Answer 5

rods = photoreceptor for low light
cones = photoreceptor respsonsible for colour vision

Question 6

what is the macular?

Answer 6

functional centre of the retina – gives 20/20 vision – best colour vision

Question 7

what is the fovea?

Answer 7

an area of closely packed cones for accurate vision

Question 8

what is found in the choroid?

Answer 8

all the blood vessels

Question 9

what happens during progression of AMD?

Answer 9

• retinal pigment epithelium cells toward the rear of the retina malfunction and die
• rods and cones adjacent to the RPE cells die
• choroid layer develops abnormal structure and physically displaces overlying neural retina

Question 10

why are RPE cells important?

Answer 10

they are needed for eyes to function correctly so the consequences of them being destroyed is significant

Question 11

6 functions of RPE cells?

Answer 11

1) regeneration of bleached opsins
2) phagocytosis of damaged photoreceptor membranes
3) transepithelial transport of important nutrients
4) secretion of growth factors essential for the retina
5) absorption of light
6) protection against photo-oxidation

Question 12

which type of AMD account for 90% of cases and is currently incurable?

Answer 12

the dry variant

Question 13

what are the 3 problems with restoration of RPE cells through cell transplantation?

Answer 13

• Restoration of central vision is at the expense of an area of peripheral vision
• Lengthy and technically challenging operation to do - must remove RPE layer and implant RPE at disease site
• Follow up procedure is required to remove compression medium (oil drop)

Question 14

a possible solution is using RPE cells from donor material however what are the problems with this?

Answer 14

• hard to come by
• RPE cells show a limited capacity to proliferate in vitro
• RPE phenotype tends to degenerate with time in culture

Question 15

could use ES cells grown in vitro but what is a problem?

Answer 15

delivery of the cells

• patients are typically elderly with an aged bruchs membrane
• cells may fail to attach to the bruchs membrane

Question 16

what is a solution to cell suspensions failing to attach to the bruchs membrane?

Answer 16

could manufacture an artificial membrane by engineering a patch and attaching the undamaged RPE cells to it

Question 17

is the cell coated patch effective in preliminary tests?

Answer 17

yes it is - clinical trials now underway to test safety and soon efficacy

Question 18

describe the cross section of macular?

Answer 18

choroid - bruchs membrane - retinal pigment epithelium - cone cells - light