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

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Flashcards in L03 -Introduction to structure and electrodiagnostics of the eye (BB) Deck (20)
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Difference between hypermetropia and presbyopia

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.



Clouding of lens in they eyes - decreased vision


Bruchs membrane

Connective tissue layer between retina and choroid


_% refraction at tear surface of cornea



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

Hyperopia, Myopia


Cornea and lens are avascular because

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


Name one maculopathy

RPE disorder


Name one optic neuropathy

Glaucoma - apoptotic axonal death gives local loss in neural rim


Name one brain related vision disorder

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


!Increase in ICP could lead to

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


Where do the cornea and lens get metabolic support from?

AH (Aquaeous humour)


What produces AH?

Cillary body


What is on top of cillary body?

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


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)?



Anterior chamber?

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


Standard IOP (intraoccular pressure)

15 +/- 3 mmHg, high IOP = glaucoma


Best disease - what is it? Arden ratio?

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.


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

Sum up, cancel


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

They all point to the front of the eye


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?

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