L03 -Introduction to structure and electrodiagnostics of the eye (BB)

Question 1

Difference between hypermetropia and presbyopia

Answer 1

Both longsightedness but presbyopia is long-sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.

Question 2

Cataract

Answer 2

Clouding of lens in they eyes - decreased vision

Question 3

Bruchs membrane

Answer 3

Connective tissue layer between retina and choroid

Question 4

_% refraction at tear surface of cornea

Answer 4

85%

Question 5

Axial length of eyes determine focusing power - therefore short eye ___opia, long eye ___opia

Answer 5

Hyperopia, Myopia

Question 6

Cornea and lens are avascular because

Answer 6

Clear light is needed to get to the back of the eye

Question 7

Name one maculopathy

Answer 7

RPE disorder

Question 8

Name one optic neuropathy

Answer 8

Glaucoma - apoptotic axonal death gives local loss in neural rim

Question 9

Name one brain related vision disorder

Answer 9

Amblyopia/Lazy eye - functional under development of one eye due to impaired cortical stimulation

Question 10

!Increase in ICP could lead to

Answer 10

Papilledema - where ICP leads to optic disc swelling and can also translate along pial sheaths and local swelling of optic nerve occurs, followed by atrophy

Question 11

Where do the cornea and lens get metabolic support from?

Answer 11

AH (Aquaeous humour)

Question 12

What produces AH?

Answer 12

Cillary body

Question 13

What is on top of cillary body?

Answer 13

Trabecular meshwork (network of blood vessels with holes in them)

Question 14

What do the epithelium have that lets through the clear part of the blood and keeps the RBC clear of the eye (letting O2, glucose to get across and float around the lens and into the ant chamber)?

Answer 14

Pumps

Question 15

Anterior chamber?

Answer 15

The anterior chamber (AC) is the fluid-filled space inside the eye between the iris and the cornea’s innermost surface, the endothelium. Aqueous humor is the fluid that fills the anterior chamber. Fluid leaves via anterior chamber angle. When blocked = glaucoma as intraocular pressure builds up

Question 16

Standard IOP (intraoccular pressure)

Answer 16

15 +/- 3 mmHg, high IOP = glaucoma

Question 17

Best disease - what is it? Arden ratio?

Answer 17

Best disease (also known as vitelliform macular dystrophy) is an inherited form of macular degeneration characterised by a reduction of central vision.

Arden ratio = 1.3 (normal ratio should be > 2.0)
*The ratio of the voltages (i.e. light peak divided by dark trough) is known as the Arden ratio.

Question 18

Radial retinal cell currents sum up/cancel, lateral retinal cell currents sum up/cancel

Answer 18

Sum up, cancel

Question 19

What does the eye’s curvature imply for GC and photoreceptors?

Answer 19

They all point to the front of the eye

Question 20

E.g. of clinical electroretinograms:
Congenital stationary night blindness
a) It is due to?
b) what is missing?
c) Response under light adapted conditions and flickering light is normal/abnormal?

Answer 20

a) Genetic mutation on GluR of BP cell (one which allows communication b/n rods and ON-BP cells)
b) no B-wave under (scotopic (dark) conditions
c) Normal