Primary Open Angle Glaucoma

Question 1

what size are the pores at the lamina cribosa in? what region ?

Answer 1

the pores are LARGER superiorly and inferiorly.
the s=pores are small nasal and temporarly

Question 2

general anatomy
what are the CONNECTIVE TISSUE like in lamina cribosa? region?

(connective tissue vs pore size)

Answer 2

• the connective tissue sheets are SPARSE, SMALLER, thinner (hence weaker) in the
• superiorly and inferiorly regions

Question 3

Saddle topography is what the lamina cribosa looks like. t/f

Answer 3

true

Question 4

what pathways mediate the rgc loss in the lamina?

Answer 4

RGC axon loss is mediated through two main pathways:
•
Axon compression
•
Astrocyte-mediated damage

Question 5

In response to IOP and hoop stress, the lamina deforms by….

Answer 5

DISPLACING POSTERIORLY AND CHANGING ITS PORE SIZE AND SHAPE.

Question 6

The cribrosal plates rotate with greatest rotational displacement…

Answer 6

observed peripherally.

Question 7

in axon compression of the lamena
the IOP exerts forces perpindicular to the globe. what is the secondary force exerted as a result of the IOP force?

Answer 7

an expansive force (like a beam). the force is expansive but does not mean the sclera actually expands. its just saying the force is expansive.

Question 8

the scerla is a rigid structure. instead of it there is a force called the

Answer 8

hope stress. the vectors of this force is parrell. but the scerla absorbs it so it doesnt actually expand.

Question 9

what is pressure 1 exerted on the sclera?
what is pressure 2 exerted on the sclera?

Answer 9

IOP -its a outward force pushing on sclera
HOOP stress -its within scleral walls

Question 10

What area of the eye is going to succumb to this pressurized system first? lamina or the sclera

what regions of the lamina are succumbed. ?

Answer 10

lamina

superiorly and inferior -because thats where the connective sheets are sparse and thin AND the PORES are large here.

Question 11

what are the three things the lamina is going structually going to do in response to the IOP force and the HOOP stress force?

Answer 11

1. dispace posteriorly
2. the laminar pores will change shape and size (pores are horizontally and elongated)
3. the cribosal plates become rotated peripherally. 90 degree. goes from the cribosal plates being horizontal to now being vertical before coming into the optic cup.

Question 12

where in the lamina would i expect to see the greatest strain?

Answer 12

the weaker areas.
-(superiorly and inferior). the septa are thinner here.
that’s why we have arcuate defects including those originating from macular region
-PERPHERIALLY because of the cribrosal plates rotation being observed peripherally ( this is why we have perpheral defects) and I also know the peripheral axons originated from distal retina to the onh

Question 13

when it comes to axon compression.
a thin central corneal thickness means its due to low IOP. Ture or false.

Answer 13

FALSE. a thin central corneal has nothing to do with IOP. a thin cct is because of the forces. the corneal is continous with the scerla, the sclera is continus with the cornea. hence, the cornea is affected.

that’s just an association but not always true .

Question 14

-is how responsive a tissue is to forces

a weak eye is _____.
a strong eye is non - ______/

Answer 14

compliance.

Question 15

a high PAC READING must mean its a strong eye or NON-compliant eye.

Answer 15

true. just think of compliance to forces. like the lamina is “ bowing “ to forces.

Question 16

refractive myopia is a risk factor for glaucoma. > t or F

Answer 16

false. its axial. because axial myopia means long eye ball. and it can alter the laminar and sceral properities.

Question 17

After impingement of the nerve fibers passing through vulnerable regions of the lamina, two main events happen:

Answer 17

retrograde loss
anterograde loss

Question 18

(loss upstream of damage—cell bodies)

Answer 18

Retrograde loss.
Failing to deliver neurotrophins from LGN and SCN (following axonal damage at level of lamina) results in cell body degeneration.

Question 19

loss downstream of damage—axons)

Answer 19

Anterograde loss (Following focal injury to the axon, the downstream compartments of an axon systematically degenerate) 
**Wallerian Degeneration** kinda like apotosis (an organized way of death)

Question 20

astrocyte-mediated damage of retinal ganglion cells is when

Answer 20

the astrocytes become sensitive to IOP changes and starts to not become helpful to the axons. may actually release toxins to those axons.

Question 21

in the vascular theory, the mechanisms of reduced ocular blood flow to the ONH are:

Answer 21

1. iop induced relative to compression OF SPCA
2. faulty regulation ( diabetes, or htn)
3. decreased ocular perfusion pressure

Question 22

pre-perimetric, mild, and moderate HTVF are symptomatic. t/f

Answer 22

false. they are typically no symptoms. ITS THE SEVERE, that is sysmptomatic for visual field loss.