Flashcards in L03 -Introduction to structure and electrodiagnostics of the eye (BB) Deck (20):
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
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
Cornea and lens are avascular because
Clear light is needed to get to the back of the eye
Name one maculopathy
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?
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)?
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