Eye Flashcards
Normal tear menisucs is _mm above eyelid margin
1mm
Which has a lower refractve index air or tear film
air
what are the 2 layers of tear film
lipid layer over mucoaqueous phase
Tear film thickeness ___um
3.4um
steady state volume of tears is
7.4uL
Name 2 glands part o f the accessory lacrimal gland
Glands of Krause
Glands of Wolfring
Which ions regulate osmotic flow
Na, K, Cl
Which ion regulated tear pH
Bicarbonate
Most common immunoglobulin in the tear film
IgA
Corneal avascularity is maintained by
VEGF receptor 1 . Blocks VEGF A
Oxygen supply to cornea via
precorneal tear film
Primary metabolic substrate of cornea is
Glucose
Can Bowman’s layer regenerate
No
Why does LASEK cause central haze compared to LASIK
LASEK Bowman layer is removed whereas in LASIK bowman layer transected by retained
Stoma makes up _% corneal thickness
90%
Major type of collagen in stroma
Type I
Which collagen type associated with stromal healing
Tpye III
AFter collagen____ are second most abundant biological constintuent in corena
Proteoglycans
Most abundant collagen in Descemet membrane
Type IV
aqeous humour is secreted by
Non pigmented ciliary epithelium
Aqueous humour has high or low protein content
low
Aqueous humour has high or low acorbate content
high
refractive index of aqueous humour
1.336
Lens refractive index
1.390
Lens relies on ____ for ATP production
glycolysis
What gives the lens a high refractive index
High amount of porteins suchs as crystallins
Main collagen type in lens capsule
Type IV
Which part of lens capsule is thicker anterior or posterior
anterior
Wavelenghth shorter than 400nm is referred to as
UV light
Wavelenghths lower than 30nm is blocked by which parts of the eye (2)
cornea and ascorbate
Vitreous makes up __ % volume of the eye
80
Stickler syndrom is due to mutation in gene COL2A1 which codes for_____
Type II collagen
which part of the eye has highest rate of oxygen comsumption
retinaa
light induces ________ , leading to cascade of reaction in the ______ outer segments called _______ which convertes light energy into electrical enegy
hyperpolarisation, photoreception, phototransduction
which are more sensitive to light, rods or cones?
rods
Two laminar structures line the back of the eye _____ and ____
RPE and neural retina
name the 3 glial cells in the retina
Muller, astrocytes, microglia
rods are highly sensitive and can be activated by a ____ photon and have a ____ surface area compared to cones
single, wider surface area
Cones are _____ sensitive than rods but can adapt to a wider range of light intensities and respond more rapidly to ____ stimulation
less, repetitive
In rod outersegments, there are roughly ____ discs and __________ membrane bound rhodopsin molcules in each disc
1000 discs
1 million rhodopsin molecules
rhodopsin in insensitive to ______ light
red light
rhodopsin ins embedded in the ____ membrane of outer segment
lipid membrane
in dark responses of rod:
rhodopsin is active or inactive?
Na channels open or closed
the rod is in a depolarised or hyperpolarised state?
glutamate released or not at synpatic cleft to bipolar cell?
bipolar cell hyperpolarised or depolarised
inactive
open
depolarised
glutatmate released
hyperpolarised
In light responses:
rhodopsin is active or inactive?
Na channels open or closed
the rod is in a depolarised or hyperpolarised state?
glutamate released or not at synpatic cleft to bipolar cell?
bipolar cell hyperpolarised or depolarised
active
closed
hyperpolarised
glutamate not released
bipola cell depolarised
S cones, short wavelength sensitive cones create what colour. vision
blue yellow
Middle waveleghth sensitive cones detect what type of colour
black white high resolution achromatic contrast
L cones create what colour vision
red green
what is the most common RHO mutation in RP
P23H
What are the 3 main cells involved in information flow from photoreceptor to optic vernce
Photoreceptor -> bipolar->ganglion
mutation of which gene leads to Leber congential amaurosis
RPE 65
RPE is a monolayer of epithelial cells that lie between _____ and _____
choriocapilliaris and photoreceptor outersegments
how many RPE cells per eye
4-6million
RPE cells are joined on the apical side by ___ ____
tight junctions
where are pigment granules in RPE cells
cytoplasm
this visual cycle is the conversion of ______ to _______ _______
11 cist retinal to all trans retinal to all trans retinol
this isemoersation of 11 cis retinal to all trans retinal is known as
bleaching
Phototransduction occurs where in the photoreceptor
photoreeptor outer segments
Int he visual pathway what is the first order neurone and second order neurone
first - photoreceptor ( rod or cone)
second - bipolar cell which synapses with ganglion cell
What are the 2 populations of ganglion cells and their function
parvocellular - fine VA and colour
Magnocellular - motion detection and coarser vision
At the optic chaism _____ fibres cross and _____ fibres remain uncrossed
nasal
temporal
THe optic tracts progress to the _________ on the ______________
lateral geniculate nucleus
posterior surface of the thalamus
In the LGN crossed fibres terminate to
Lamniae 1,4,6
In the LGN uncrossed fibres terminate to
Laminae 2,3,5
in the LGN ganglion cell fibres synapse with cells that connect via optic radiations to _______ area____
occipital cortex area 17
IN utero, at how many weeks do the edges of the optic stalk seal near the forebrain
5-6 weeks
What is the name of the remnant of glial cells and posterior hyaloid vessels that may persist at the optic nerve head
Bergmeister’s papilla
WHat is the anterior remnant of hyaloid vessels on the posterior lens capsule
Mittendorf’s dot
When are optic nerve fibres maximal
in utero, decrease before birth
How many ganglion cells axons are there
1.2 million
At what point do ganglion cell acons become myelinated
once exited lamina cribosa
lenghth of optic nerve
40mm
what is the role of microglial cells
resident macrophages
what is the role of astrocytes
structural support and regulate potassium
what is the role of oligodendrocytes
myelination
diameter of optic disc
1.5mm
How long optic nerve orbital portion
25mm
Ciliary ganglion lies between ____ and______
optic nerve and lateral rectus
How long intracanalicular portion of optic nerve
5mm
dimensions of optic chiasm
12mm x 8mm
Which fibress pass in the anterior and inferior chiasm
inferior nasal fibres
which fibres pass in the posterior and superior chiasm
superior nasal
If a bitemporal hemianopia is superioirly dense where is the compression
inferior compression e.g. pit adenoma
If a bitemporal hemianopia is inferiorly dense where is the compression
superior compression e.g craniopharnygioma
Pretectal nucleus is reponsible for
pupillary light reflexes
Suprachiasmatic nucleus responsbile for
circadian rhythm
Pulvinar nucleus responsible for
Visual attention and motor integration
Parvocellular reticular formation responsible for
arousal
Blood supply of optic tract
Posterior communicating artery
Pial arteries
From pretectal nuclues fibres pass to _____ nuclei
Edinger Westphal nuclei
From EW nuclei parasympathetic fibres travel in the _______ to the ________
oculomotor nerve to the ciliary ganglion
From EW nuclei postganglionic fibres travel in the _______ to the ________
short ciliary nerves to the constrictor pupillae
In the lateral geniculate nucleus, layers 1 and 2 receive data from
peripheral retina vai magnocellular pathway
In the lateral geniculate nucleus, layers 3-6 receive data from
fovea via parvocellular pathway
where do optic radiations terminate
striate visual cortex area 17
Are parvocellular fibres fast or slow fibres
slow fibres
magnocellular fibres are fast or slow fibres
fast fibres
parvocellular fibres go to which layers of LGN
layers 3-6
magnoceullular fibres go to which laters of LGN
layers1-2
conjunctiva emryologically derived from?
surface ectoderm
name the 2 accessory lacrimal glands
Krausse and Wolfring
Where is Gland of Krause
superioir fornix
Where is Gland of Wolfring
superior tarsal border
the accessory glands provide ____ tear production
basal
conjunctival sac has ___ microlitre capacity
25-30
