Qbank must know 2 Flashcards
Indocyanine green (ICG) wavelength
ICG dye absorbs light of wavelength 805nm and reflects light of wavelength 835nm
botulinum toxin (mechanism)
Botulinum toxin inhibits the release of ACh from PREsynaptic nerve terminals
largest cranial nerve is:
the trigeminal
sympathetic trunk extends
extends from the base of the skull to the coccyx
sympathetic trunk enters the thorax
It enters the thorax through the neck of the first rib
CMO cystoid macular oedema. Which retinal layer accounts for the petalloid appearance in fluorescein angiography?
Outer plexiform layer
The radiating fibres of Henle in the outer plexiform layer lead to the cystic spaces in CMO.
Jaw opening muscles
lateral pterygoid and mylohyoid.
Short posterior ciliary artery supply
choroid and and outer4 layers of retina
Argyll Robertson pupil
light near dissociation
light absent
near present
defect afferant pathway
Adie’s tonic pupil
mid dilated
lesion in ciliary ganglion
sluggish everyway
corneal clarify factors
regular arrangement of epithelium
regular arrangement of lamellar laminin (GAG keratan sulphate)
Endothelial pump Action
avascular
diameter of the adult cornea
11.7 mm horizontally and 10.6 mm vertically.
Diploë
is the name of the spongy bone that separates tables of compact bone
Sutures
immobile, rigid articulations
Site of opening into nose: Middle meatus
? sinus
Frontal
Maxillary
Ethmoidal (anterior and middle groups)
Site of opening into nose: Superior meatus ? sinus
Ethmoidal (posterior group)
Site of opening into nose: recess or superior meatus ? sinus
Sphenoidal
posterior blepharitis
Meibomian gland dysfunction
Meibomian glands
are modified sebaceous glands which produce an oily substance that forms part of the precorneal tear film
chalazion
A chalazion is a lipogranulomatous inflammatory cyst resulting from a blocked
Meibomian gland.
important differences between extraocular muscles and normal skeletal
muscle
1.The connective tissue of the extraocular muscles,
including the epimysium (a sheath surrounding the whole muscle) is generally thin
and delicate by comparison
2.The muscle fbres are more loosely packed, with the
larger diameter (10–40 μm) fbres occupying the centre and the smaller fbres (5–15
μm) placed peripherally in the muscle.
3.Extraocular muscle also has many specialised
sensory and proprioceptive endings, including long muscle spindles almost 1 mm in
length, which provide feedback about muscle activity to the central nervous system
Lastly, extraocular muscle is more vascular than normal skeletal muscle.
Schwalbe’s line marks the termination of
Descemet’s membrane
lens capsule is thinnest at
Posterior pole
posterior pole 2–3 µm
The anterior pole is 9–14 µm
peri-zonular region the capsule is 17–28 µm thick
vitreous base attaches
peripheral retina and pars plana
vitreous base is a three-dimensional band that extends approximately 2 mm
either side of the ora serrata and is usually attached to the peripheral retina and pars plana
Bruch’s membrane is composed of 5 layers (basement)
the basement membrane of the choriocapillaris, an outer collagenous layer, an elastin layer, an inner collagenous layer and the basement membrane of the RPE.
lateral canthal tendon inserts into
Whitnall’s tubercle
Whitnall’s tubercle
is a small prominence of bone lying just inside the lateral orbital rim. Eisler’s fat pad lies immediately anterior to the lateral canthal tendon, deep to the orbital septum
Nerve innervation of iris (parasympathetic, sympathetic, and sensory)
The parasympathetic nerves supplying the iris originate in the Edinger–Westphal nucleus and synapse in the ciliary ganglion. Their postganglionic fibres travel via the
short ciliary nerves and supply the sphincter pupillae muscle
The dilator pupillae is predominantly innervated by unmyelinated sympathetic fibres originating in the superior cervical sympathetic ganglion
The sensory innervation of the iris is via both the long and short ciliary nerves, which derive from the nasociliary nerve (and ultimately V1)
optic canal connects
middle cranial fossa and the orbital apex
posterior to anterior orientation of the optic canal
Inferolateral
posterior to anterior the optic canal runs slightly inferiorly and around 36o
laterally through the sphenoid
optic canal narrowest part
orbital opening and widens posteriorly
ciliary body
ciliary body has a greater anteroposterior length temporally than nasally, and is generally at its longest inferotemporally. It varies with the size of the globe, measuring 5.6–6.3 mm temporally and 4.6–5.2 mm nasally
A The blood supply to the ciliary body
via the anterior ciliary arteries and the long posterior ciliary arteries
middle radial layer of the ciliary muscle is continuous with
corneoscleral meshwork
outer longitudinal layer of the ciliary muscle attaches
scleral spur
The ciliary body stroma lies between
ciliary body stroma lies between the ciliary muscle and the ciliary epithelium.
Iris capillaries are fenestrated/ non-fenestrated
Iris capillaries are non-fenestrated with
tight junctions and pericytes, contributing to the blood–ocular barrier
Iris blood supply
The major arterial circle (which is often incomplete) derives its blood supply from the anterior ciliary arteries (which travel anteriorly with the extraocular muscles before piercing the sclera)
and the long posterior ciliary arteries (which pierce the sclera near the
optic nerve and run anteriorly between the sclera and choroid to the ciliary body)
The minor arterial circle of the iris is at the level of the collarette, and is also often
incomplete. From here vessels continue inwards to the pupillary border.
lymphatic drainage
1) right side of the head and neck, and the right arm
2) the rest of the body
1) right lymphatic duct - right subclavian vein
2) thoracic duct - left subclavian vein
The blood from the subclavian veins returns to the heart via the brachiocephalic
veins and superior vena cava
three principal layers (tunica) of blood vessels
- Intima
- Media
- Adventitia
The intima contains the endothelium supported by the internal elastic lamina. The
latter is typically fragmented in giant cell arteritis
The media is the main muscular layer of the vessel, containing smooth muscle cells,
and varying amounts of elastic fibres (principally in medium to large arteries).
The adventitia (sometimes called tunica externa) is the MAIN connective tissue layer, and in arteries this contains the external elastic lamina.
Veins vs artery
Veins have a thinner media, larger lumen and contain proportionally less muscle
and less elastic tissue than arteries.
plasma vs aqueous
- Higher levels of lactate and ascorbate
- Similar concentrations of sodium, potassium and magnesium;
- Slightly lower levels of bicarbonate;
- Lower levels of glucose and calcium (about half that of plasma), and much lower levels of albumin.
Transcription
DNA → RNA
Translation
RNA → peptide formation
Matrix metalloproteinases (MMPs) are dependent endopeptidases
zinc and calcium-dependent endopeptidases
MMPs are released by
neutrophils during the acute inflammatory response (they mediate cell and tissue damage, along with free radicals from the
respiratory burst),
and also by cells in normal tissues for growth, maintenance,
repair and remodelling.
Matrix metalloproteinases (MMPs) are keep in check by
They are kept in check by endogenous tissue inhibitors of MMPs (TIMPs).
Endogenous inhibitors called TIMPs are present in normal tissues
which growth factor stimulates the differentiation of anterior lens epithelial cells into lens fibres.
Fibroblast growth factor (FGF) is one of the principal factors that stimulates
the differentiation of anterior lens epithelial cells into lens fibres.
weight of the lens is protein
1/3
90% of the lens protein
crystallins
Differentiation of anterior lens epithelial cells into lens fibres describe
This change is characterised by elongation, withdrawal from the cell cycle, expression of large amounts of crystallins and eventually the loss of organelles and the nucleus.
Lens fibres are densely packed with cytoplasmic interdigitations, and intercellular,
gap junction-like channels formed by
MIP26 (main intrinsic polypeptide 26),
which was subsequently recognized as an aquaporin and named aquaporin-0
The genes encoding the two types of α-crystallin (known as αA and αB) are found
on chromosomes
21 and 11
The genes encoding the two types of α-crystallin (known as αA and αB) are found
on chromosomes 21 and 11, respectively
The corneal endothelial cell pump moves what (sodium/ potassium) from the stroma to the aqueous by active transport
Sodium and bicarbonate
The corneal endothelial cell pump moves sodium and bicarbonate from the stroma to the aqueous by active transport. This is mediated by a sodium/potassium-dependent ATPase and a bicarbonate-dependent ATPase, and is facilitated by co-transporters.
Potassium and chloride move to the aqueous predominantly by
passive diffusion
Pericyte
Pericytes are contractile cells embedded in the basement membrane of vessels, to which they contribute. They are involved in a number of regulatory functions, communicating with the endothelial cells by paracrine signalling and direct contact.
They play a key role in maintaining the blood–brain barrier, where they regulate permeability. They may also have a role in controlling cerebral blood flow.
Pericyte coverage is highest in
Retinal vessels
Pericyte coverage is highest in the retinal vessels, with a relative frequency of 1:1
pericytes to endothelial cells. This may be because of the meticulous metabolic
demands of the retina and the requirement to maintain the blood–retinal barrier.
Melatonin is synthesized by photoreceptors in conditions of light/ darkness
darkness
Melatonin is synthesized by photoreceptors
in conditions of darkness and suppresses dopamine production
Rod outer segments complete their renewal cycle
About 10% of the rod outer segment is phagocytosed daily, and it takes 9–10 days
for the renewal cycle to be complete
Colobomas are
Colobomas are a result of failed or incomplete closure of the embryonic optic
fissure, and are thus found inferonasally
Main constituents of adult vitreous are (collagen)
Other than water, the main constituents of adult vitreous are type II collagen
and hyaluronate
which part of vitreous first to liquefy?
The central vitreous is the first to liquefy. The vitreous reduces in size, and liquefied
vitreous (from pooling of hyaluronate) escapes into the subhyaloid space, leading to
posterior vitreous detachment.
mitochondrial-inherited condition (2)
Leber’s hereditary optic neuropathy
Kearns–Sayre syndrome
Histones and DNA charge
Histones have a high positive charge, allowing them to associate with DNA
which has a negative charge
Histone contains
Lysine and arginine
Lysine and arginine are positively charged
(basic) amino acids, and are found in large numbers in histones
corneal dystrophy (inheritance)
it is safe to assume that a corneal dystrophy is autosomal dominant
Apart from macular corneal dystrophy, which is autosomal
recessive
Reis–Buckler is characterised by / stain
Reis–Buckler is characterised by granular deposits in the epithelial basement
membrane. These stain with Masson’s trichrome. It manifests clinically as
recurrent corneal erosion and corneal opacification which may require corneal
grafting
Antigen presenting cells (APCs) include
monocytes, macrophages, dendritic cells, some B cells, and activated endothelial cells. They constitutively express MHC class II molecules.
NOT T CELLS
MHC class I molecules are present on
every nucleated cell
HLA-B27 is an example of an MHC class I molecule.
MHC class II molecules are only expressed by
antigen presenting cells (APC)
The electrooculogram (EOG) measures the
resting electrical potential between the retinal
pigment epithelium (electrically negative) and cornea (positive)
CORNEA POSITIVE
involved in colour vision
P pathway. area V8 of visual cortex . geniculate layer 3-6
Purkinje shift
Purkinje shift refers to a shift in peak spectral sensitivity, from 555 nm to 505 nm, with dark adaptation. Dark adaptation does increase light sensitivity by a factor of 1,000, but this is not the Purkinje shift.
Light adaptation (time)
5 minutes
dark adaptation (time)
20 minutes
Dark adaptation
It is biphasic The dark adaptation time is related to the time required to build up rhodopsin stores
decrease levels of IL-2
Cyclosporin and tacrolimus
anti-TNF agents
Infliximab and etanercept
monoclonal antibody against the CD20 protein
Rituximab
During a cataract operation, the intraocular lens is accidentally placed in the sulcus rather than within the capsular bag.
This will result in:
myopic shift
The lens is placed more anteriorly and therefore results in a myopic shift compared to the predicted outcome.
disciform scar
fibrous metaplasia of RPE cells with deposition of collagen causing the disc-shaped mass
retinoic acid
Hox gene
FMR-1 gene
Fragile-X Syndrome
PAX-3 gene
Klein-Waardenburg syndrome
syndrome is characterised by pigmentary abnormalities such as hair and iris hypopigmentation, dystopia canthorum and congenital sensorineural hearing loss.
Rb gene
retinoblastoma
Bcl-2
anti-apoptotic gene
corneal stroma is composed of ??? layers of flattened collagenous lamella
200-250 layers
The corneal stroma is composed of 200-250 layers of flattened collagenous lamellae
major functions of the complement system
three main functions:
opsonisation,
cytolysis of pathogenic organisms,
production of inflammatory mediators
Complement plays no role in presenting antigens
