IDK Flashcards

Question

Oxybuprocaine

Answer 1

Local anaesthetic - toxic if used systemically Bacteriostatic so proxymethocaine preferred for corneal scrapes Tetracaine has longer anaesthetic effect that oxybuprocaine

Answer 2

The muscles of facial expression are innervated by the facial nerve and include: procerus frontalis corrugator supercilii orbicularis oculi zygomaticus major and minor levator labii nasalis depressor supercilii occipitofrontalis buccinator

Answer 3

Peptides T3>T4 99% bound to thyroxine binding globulin Thyroxine sensitises myocardium to NA

Answer 4

ACID T1 - ALLERGIC IgE mediated - quick onset after exposure E.g. bee sting, latex, drug allergy T2 - CYTOTOXIC/ANTIBODY-MEDIATED E.g Haemolytic reactions, Good pasture syndrome, Hyperacute graft rejection, blood transfusion reaction T3 - IMMUNE COMPLEX/IGG/IGM MEDIATED Immune complex deposition E.g Hypersensitivity pneumonitis, SLE, PAN, RA, glomerulonephritis T4 - DELAYED/CELL-MEDIATED E.g. chronic graft reactions, contact dermatitis.

Answer 5

Miosis - reacts normally to light Partial ptosis - disappears w/ topical phenylephrine Conjunctival injection Updrawing of lower eyelid which looks like enophthalmos Decreased sweating of face

Answer 6

At 12wks, together the Nuchal scan (Thickened) bHCG (Elevated) PAP (Reduced) identifies those at high risk of a Down syndrome pregnancy in greater than 80% of cases.

Answer 7

cones - pedicles rod - spherules

Answer 8

Haller's layer comprises large arteries and veins. Sattler's layer, which lies above Haller's layer, is composed of arterioles and venules which supply the choriocapillaris directly above. Above layers are not fenestrated unlike the capillaries in the choriocapillaris which lie above both layers -> Fluoroscein leakage is seen in the choriocapillaris.

Answer 9

CLINICAL posterior pole -> macular lutea ->fovea centralis ANATOMICAL area centralis -> fovea -> foveola posterior pole: area centralis (the area between the vascular arcades) macula lutea: fovea (1.5 mm diameter area, yellow from xanthophyll) fovea centralis: foveola (0.35mm central depression with thickened margins)

Answer 10

Botox binds irreversibly to presynaptic receptors on the nerve terminal of the neuromuscular junction, inhibiting the release of acetylcholine following an action potential.

Answer 11

Form ant 1/6th of eyeball LENGTH 10.6mm vertically 11.7mm horizontally (10mm at birth) Post diameter circular 11.7mm THICKNESS Centre is thinnest 0.5-0.6mm Peripherally 0.7mm RAD OF CURVATURE Ant surface - 7.7mm Post surface - 6.9mm More curved in vertical than horizontal plane (regular astigmatism) n=1.37

Answer 12

FRONT TO BACK EPITHELIUM BOWMAN'S LAYER SUBSTANTIA PROPRIA DESCEMET'S MEMBRANE ENDOTHELIUM

Answer 13

Diploë is the name of the spongy bone that separates tables of compact bone.

Answer 14

MEDIAL (post to anterior) - Body of sphenoid - Ethmoid - Lacrimal - Maxilla FLOOR - Maxilla - Palantine - Zygoma LATERAL WALL - Zygoma - Great wing of sphenoid ROOF - Frontal -Lesser wing of sphenoid

Answer 15

tarsal glands embedded in the tarsal plates. openings, 20–25 in each lid posterior to both the lash line and the grey line modified sebaceous glands - oily substance forms outer layer of the precorneal tear film Meibomian gland dysfunction/posterior blepharitis Anterior blepharitis involves crusting/debris and inflammation around the lash line, and the two often coexist. A chalazion is a lipogranulomatous inflammatory cyst resulting from a blocked Meibomian gland.

Answer 16

Parasympathetic supply lacrimatory nucleus OF FACIAL CN7 -> nervus intermedius -> pterygopalatine ganglion -> via the maxillary nerve to its zygomatic and zygomaticotemporal branches ->via the lacrimal nerve to the gland. Sympathetic supply, superior cervical ganglion ->nerve plexus surrounding ICA -> deep petrosal nerve to its zygomatic and zygomaticotemporal branches ->via the lacrimal nerve to the gland. Sensory supply - From lacrimal nerve, which is a branch of the trigeminal nerve (V1).

Answer 17

Connects middle cranial fossa with inferotemporal fossa Transmits -meningeal n of mandibular n middle meningeal artery and vein

Answer 18

Thin, delicate CT including epimysium sheath Loosely packed muscle fibres Larger fibres in centre, small in periphery Long muscle spindles 1mm in length More vascular

Answer 19

Two Zebras Bit My Coccyx -Temporal -Zygomatic -Buccal -Mandibular -Cervical

Answer 20

posterior pole 2–3 μm anterior pole 9–14 μm peri-zonular region the capsule is 17–28 μm

Answer 21

Peripheral retina and pars plana

Answer 22

pars plicata forms the anterior portion and is contiguous to the posterior surface of the iris. It represents approximately one quarter of the whole CB. The pars plana, the posterior portion of the CB, is contiguous to the choroid at the ora serrata

Answer 23

Outer to inner VESSEL LAYER -loose CT w/ melanocytes - embedded w/ large-medium vessels (branches of short posterior ciliary arteries) CAPILLARY LAYER - wide-bore capillaries w/ sac like dilatations - again supported by CT and melanocytes - lined by continuous layer of fenestrated endothelial cells - capillary density and bore greatest at macula BRUSCH'S MEMBRANE 2-4micrometers thick 1. BM of choriocapillaris 2. Outer collagenous layer 3. Elastin layer 4. Inner collagenous layer 5. BM of RPE

Answer 24

AP length temporal (5.6-6.3mm) >nasal (4.6-5.2mm) Blood supply - via the - anterior ciliary arteries - long posterior ciliary arteries The ciliary body stroma lies between the ciliary muscle and the ciliary epithelium.

Answer 25

outer longitudinal layer - attaches to the scleral spur middle radial layer - continuous w/ corneoscleral meshwork third (innermost) - composed of circular fibres CONTRACTION OF CILIARY MUSCLES ESP 1 AND 3 -> used in convergence, accomodation

Answer 26

Iris capillaries are non-fenestrated - tight junctions and pericytes contribute to the blood ocular barrier. Most of the anastomoses between the major and minor arterial circles run through the IRIS STOMA in a radial manner. (Anterior border layer - significant vascularisation here suggests ischaemic insult.) The MAJOR arterial circle of the iris receives blood from - anterior ciliary arteries (which travel anteriorly with the extraocular muscles before piercing the sclera) - 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

Answer 27

Right lymphatic duct (empties into right subclavian vein) - drains right head, neck, arm Thoracic duct (empties into left into left subclavian vein) - drains rest of body

Answer 28

Internal elastic lamina (part of intima) is fragmented in giant cell arteritis.

Answer 29

* Higher levels of - lactate - ascorbate; * Similar concentrations of - Na - K - Mg * Lower levels - bicarbonate; - glucose - calcium (about half that of plasma), - much lower levels of albumin.

Answer 30

Stage of collagen synthesis Transcription DNA → RNA TRANSLATION RNA → peptide formation The basic amino acid sequence is repeating triplets (Glycine-X-Y )n where X is often proline, Y is often hydroxyproline Polypeptides (primary structure) twist into a left-handed helix (secondary structure; ≠ α-helix) POST-TRANSLATIONAL MODIFICATION (ENDOPLASMIC RETICULUM) - Vitamin C-dependent HYDROXYLATION of the Y-position amino acid - GLYCOSYLATION - TRIPLE HELIX FORMATION (tertiary structure) linked by covalent S–S bonds EXCRETION FROM CELL Cleavage of terminal peptide chains, making it insoluble (EXTRACELLULAR MODIFICATION) Lysine oxidation Formation of crosslinks

Answer 31

zinc and calcium-dependent endopeptidases act as an enzyme cascade to degrade extracellular matrix. required for normal tissue growth (make room) regulated by Endogenous inhibitors called TIMPs are present in normal tissues released mainly by neutrophils in acute inflammation ___ MMPs in the cornea, - maintenance of normal framework (principally MMP-2) - remodelling following injury: MMPs: - MMP-1 (a collagenase), - MMP-2 (a gelatinase) - MMP-3 (a stromelysin), all produced primarily by the stroma, along with MMP-9 (a gelatinase) produced primarily by the epithelium. MMP-9 is involved in corneal epithelial remodelling.

Answer 32

Cytoplasmic interdigitations between lens fibres contain channels formed by MIP26 (aquaporin-0) FIBROBLAST growth factor stimulates the differentiation of lens epithelial cells into lens fibres genes encoding α-crystallin are found on chromosomes 21 and 11

Answer 33

- composed of long chains of repeating disaccharides -relatively inflexible molecules -strongly hydrophilic - form a gel resistant to compression -high negative charge

Answer 34

moves sodium and bicarbonate from the stroma to the aqueous by active transport. mediated by a sodium/potassium-dependent ATPase and a bicarbonate-dependent ATPase, facilitated by co-transporters. Potassium and chloride move to the aqueous predominantly by passive diffusion.

Answer 35

frequency of 1:1 pericytes to endothelial cells meticulous metabolic demands of the retina and the requirement to maintain the blood–retinal barrier. Conversely choroid — less dense coverage of pericytes, facilitating exchange of metabolites.

Answer 36

contractile cells embedded in the BM of vessels regulatory functions - communicating w/ endothelial cells by paracrine signalling and direct contact. -maintaining the blood–brain barrier - regulate permeability. ?role in controlling cerebral blood flow.

Answer 37

Aflibercept - decoy VEGF receptor molecule Bevacizumab VEGF mab Ranubizumab VEGF man-fragment VEGF synthesis is upregulated by TNFα, TNF-β, IL-1α, IL-6, prostaglandin E2, epidermal growth factor, fibroblast growth factor, insulin-like growth factor-1, keratinocyte growth factor and platelet-derived growth factor. All three identified VEGF receptors act via intracellular tyrosine kinase activity. ROLE - promote the division and survival of vascular endothelial cells, VEGF promotes vascular dilatation and permeability to macromolecules. It also has functions in regulating gene expression, cell migration and nitric oxide production.

Answer 38

About 10% of the rod outer segment is phagocytosed daily, and it takes 9–10 days for the renewal cycle to be complete. Melatonin is synthesized by photoreceptors in conditions of darkness and suppresses dopamine production. Conversely, local dopamine production increases during conditions of light and suppresses melatonin production. These mechanisms are involved in modulating the circadian rhythm of photoreceptor renewal, with rod disc shedding and phagocytosis occurring at first light. Cone outer segments are predominantly shed at the onset of darkness. Rod discs are phagocytosed in groups of approximately 200. It is hard to measure cone segment phagocytosis experimentally.

Answer 39

introns are removed before it leaves the nucleus as mature mRNA a poly-adenine tail provides stability to mature mRNA leaving the nucleus and helps to prevent degradation before translation a cap of ATP/GTP is added to the 5' end which facilitates binding to the ribosome the start codon is AUG which codes for methionine it is synthesised from a single strand of DNA by RNA polymerase II enzyme

Answer 40

ganglion cell layer.

Answer 41

TYPE VII 7

Answer 42

continuation of the transverse sinus ends below the jugular foramen. groove of the sigmoid sinus is on the mastoid process of the temporal bone; and runs along the border of the temporal and occipital bones. receives blood from the cavernous sinus via the superior and inferior petrosal sinuses close proximity to the mastoid air cells, infection in this region can cause thrombosis.

Answer 43

Increased -pH -Chloride - magnesium Lower everything but - (low o2 as low pH) - (almost absent protein) - (glucose is 2/3rd that of blood)

Answer 44

keratan sulphate (most common) and dermatan sulphate

Answer 45

- grows well on blood agar - main commensal of the outer eye - aerobic - non-motile - it is a Gram positive bacteria - it can produce exotoxins

Answer 46

Topical natamycin Causative organisms include Fusarium, Aspergillus Penicillium

Answer 47

alkylating agent - interferes with DNA replication by forming intrastrand and interstrand DNA cross-links. SE: most commonly bone-marrow suppression, particularly granulopoiesis and lymphopoiesis, which is almost universal. Haemorrhagic cystitis is also common, occurring in up to 10% of patients. Other side-effects include bladder cancer, hepatic toxicity, amenorrhoea and azoospermia (usually reversible).

Answer 48

Yoked muscles receive equal and simultaneous innervation in accordance with the Hering 's law. The right inferior rectus is yolked with the left superior oblique (as the eyes look right and downwards). Other options supplied are true.

Answer 49

The Purkinje effect describes the shift in spectral sensitivity from 555nm (yellow) to 505nm (blue-green) with dark adaptation as rod function overtakes cone function. This results in an enhanced sensitivity to short (blue-green) wavelengths at dusk.

Answer 50

-aD -characterised by granular deposits in the epithelial basement membrane. -stain with Masson’s trichrome. -manifests clinically as recurrent corneal erosion and corneal opacification which may require corneal grafting. NB: All corneal dystrophy is autosomal dominant apart from Macular Corneal Dystrophy (aR).

Answer 51

-aims to treat a genetic condition by replacing the abnormal gene with a healthy one or by manipulating its expression. Viral vectors include adenoviruses, retroviruses, adeno-associated viruses and herpes simplex viruses. Non-viral vectors include liposomes and naked DNA in the form of plasmids. Ribozymes (RNA that catalyses reactions) are also a tool in gene therapy but they are not vectors: they are used to cut mRNA of the target gene to block transcription.

Answer 52

Antigen presenting cells (APCs) include: monocytes, macrophages, dendritic cells, some B cells, activated endothelial cells. They constitutively express MHC class II molecules. APCs do not include T cells; the main function of APCs is to allow T cells to recognise antigens.

Answer 53

Moist Heat Temperature (oC) 121–124 - 15mins 126–129 - 10mins 134–138 - 5mins Dry Heat Temperature (oC) 160 - 180mins 170 - 60mins 180 - 30mins

Answer 54

Botulinum toxin A is a protein of Clostridium botulinum - gram +ve internalised by cholinergic nerve terminals and inhibits the exocytosis of acetylcholine.

Answer 55

nematodal infection typically affects children. posterior uveitis part of the differential diagnosis of leukocoria. Both toxocara and toxoplasma can be transmitted to humans via ingestion of animal faeces. Toxocara canis ova are shed in dog faeces; Toxocara cati ova and Toxoplasma gondii cysts are shed in cat faeces. Both toxocara and toxoplasma cause white chorioretinal lesions and, in some cases, vitritis. Infection may be asymptomatic.

Answer 56

aerobic, Gram-negative bacillus The descriptor coccobacillus is often applied, as the rods are very small and can give the appearance of cocci. Haemophilus influenzae is best cultured on chocolate agar with added X and V factors. common cause of respiratory tract infections and sinusitis, the latter becoming orbital cellulitis if spread through the orbital wall occurs. encapsulated serotypes being more virulent and invasive.

Answer 57

Adjust by -1D (if 17.5-28) If >28D, -1.5 If <17.5D –0.5 If IOL< 9.5 dioptres - keep same

Answer 58

8% iris, 12% ciliary body 80% choroid

Answer 59

Accumulation of sub retinal fluid in all types RHEGMATOGENOUS Most common Liquefaction of vitreous, vitreous traction, retinal tear/break COMMON CAISES - PVD causing retinal tear or hole - Dehiscence of the anterior retina at the ora serrata causing retinal dialysis (usually due to trauma) EXUDATIVE/SEROUS Compromised outer blood-retinal barrier COMMON CAUSES - Vascular e.g ARMD - Inflammatory e.g posterior scleritis - Neoplastic e.g. choroidal melanoma TRACTIONAL Contracting proliferative retinal membranes, abnormal vitreoretinal adhesions COMMON CAUSES - Proliferative DM retinopathy - Proliferative viteoretinopathy - ROP

Answer 60

- common cause of failure following retinal detachment surgery - more common with -large breaks, -multiple operations -duration of retinal detachment. -may also occur in untreated retinal detachment. Following the break in the retina, RPE cells migrate into the subretinal space and vitreous. The blood–retinal barrier is broken and inflammatory cells are recruited. Fibrosis and collagen production occur, contributing to the formation of retinal membranes. Contraction of these can lead to retinal detachment and, if untreated, ocular hypotony (not raised intraocular pressure) and ultimately phthisis bulbi.

Answer 61

MINS - Retraction of Descemet’s and stromal collagen - Fibrin plug formation - Stromal oedema - Invasion of leukocytes from aqueous and limbal vessels HOURS - Transformation of leukocytes and of stromal keratocytes into fibroblasts - Collagen formation - Start of epithelial regeneration DAYS - Endothelial sliding, filling in gaps in endothelium and Descemet’s WEEKS - Replacement of stroma and Bowman’s layer with scar tissue

Answer 62

calcineurin inhibitor inhibits transcription of IL2 and other cytokines TACROLIMUS, CICLOSPORIN SEs: nephrotoxicity tremor hirsutism gingival hypertrophy

Answer 63

COCAINE Fails to dilate pupil as NA reuptake inhibitor but no NA released HYDROXYAPHETAMINE ONLY fails to dilate in 3RD ORDER LESIONS as causes release of NA APRACLONIDINE (ALPHA 2 AGONIST W/ WEAK ALPHA1 ACTIVITY) Denervation hypersensitivity to apraclonidine occurs due to up regulation of iris alpha-1 after a few days Pupil dilates in all cases PHENYLEPHRINE (A1 AGONIST) - SAME AS APRACLONIDINE

Answer 64

α2 adrenoreceptor agonist lowers aqueous production AND increases uveoscleral outflow. α2 agonists such as brimonidine carry more risk of allergy (approximately 10%). However, they are considered safer than the others in pregnancy, and not contraindicated in asthma (unlike BBs).

Answer 65

Vasoconstriction Platelet aggregation

Answer 66

Eicosanoids are an important group of signalling molecules and inflammatory mediators that include prostaglandins and thromboxanes (together termed prostanoids), and leukotrienes. They can be generated as required in response to stimuli. The inflammatory response always involves prostanoid generation. The precise stimuli vary depending on cell type and include cell damage, thrombin (platelets), complement-derived C5a (neutrophils) and bradykinin (fibroblasts). They are derived from arachidonic acid, which is liberated from cell membrane phospholipids in a rate-limiting step catalysed primarily by phospholipase A2.The enzymes cyclooxygenase (COX-1 and COX-2 isoforms) and lipoxygenase then catalyse the production of different eicosanoids from free arachidonic acid. Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce inflammation by inhibiting cyclooxygenase and therefore the biosynthesis of prostaglandins, but subsequently have no effect on their actions on target tissue. Prostaglandins exert their effects by acting on G-protein coupled receptors. Thromboxane A2 is an eicosanoid which causes vasoconstriction and platelet aggregation.

Answer 67

H1 Intracellular - phospholipase C activation - increase Ca2+ Extracellular - increased vasc permeability - vasodilation - CNS depressant H2 Intracellular -Activation of adenylate cyclase - increase in cAMP Extracellular - Increase gastric acid production - Increase cardiac stroke volume __ 3 histamine receptors - g-protein coupled.

Answer 68

nature of the reflected light determines the object’s colour. ‘Colour’ = chromaticity Depends on: * Hue * Saturation * Luminance Hue is not independent of luminance (which in this context could also be referred to as luminosity or brightness): with increasing brightness, eventually all hues appear yellow-white (the Bezold–Brücke effect), whilst with very low luminosity all hues appear achromatic. The perceived colours of objects around us are a product of both the light source and the surface properties of the objects, which determine the composition of the reflected light. The maximal spectral sensitivity of green cones is 535–550 nm.

Answer 69

Dark adaptation is the process by which the retina increases in sensitivity to light in response to decreasing background illumination. The dark adaptation curve plots the light intensity required to perceive a spot of light versus time. It is bipartite, with an initial rapid (5–10 minutes) increase in cone sensitivity and then a slower period (15–30 minutes) where rods reach their maximum sensitivity. Thus dark adaptation is complete in 30 minutes in normal subjects. Fully dark adapted rods allow perception of a spot of light at least 100 times dimmer than cones. Light adaptation occurs more rapidly than dark adaptation.

Answer 70

INHIBITED BY ONCOTIC PRESSURE Oncotic pressure is generated by plasma proteins and works against aqueous humour production. Recall that the aqueous is virtually free of protein in the healthy state. PRODUCTION MAINTAINED BY - active secretion in the double- layered ciliary epithelium, - passive diffusion of ions down their concentration and charge gradients and - ultrafiltration of water and solutes secondary to the CAPILLARY HYDROSTATIC PRESSURE. Of these processes active secretion is thought to account for 80–90% of aqueous humour production.

Answer 71

Regarding hearing Depolarisation of the hair cell in the cochlea occurs due to the influx of POTASSIUM Higher frequencies are detected by hair cells near the base of the cochlea Sound is audible to humans between 20 and 20,000 Hz Sound is converted by the organ of Corti into action potentials in the auditory nerves

Answer 72

A broadband, low coherence light source is directed at the desired target A beam splitter is used to simultaneously direct the same light source at a reference mirror The reflected light from both the desired target and the reference mirror are directed onto a detector, and the interference pattern is analysed using low coherence interferometry to construct an image of the desired target.

Answer 73

12 excretory ducts. orbital portion of the gland contains fine interlobular ducts that unite to form 3-5 main excretory ducts, joining 5-7 ducts in palpebral portion

Answer 74

can be caused by a host of mutations, some of which code for rhodopsin. peripheral retinal atrophy with streaks of pigmentation (bone-spicule appearance—> fine and course strands of pigmentation) microscopy reveals evidence of retinal vessel attenuation and hyalinization. it causes night blindness it can lead to tunnel vision individuals are typically affected in early adult life

Answer 75

acidosis, raised temperature increased 2,3 DPG.

Answer 76

Junctional scotoma Anterior to chiasm at the junction of the optic nerve Sphenoid meningioma Binasal Lateral to chiasm Dilatation of 3rd ventricle in hydrocephalus Superior bitemporal Inferior to chiasm Pituitary adenoma Inferior bitemporal Superior to chiasm Craniopharyngioma; suprasellar or olfactory groove meningioma

Answer 77

Krause -> around the conjunctival fornix. Wolfring -> at the border of the tarsal plate.

Answer 78

Some Anatomists Like Freaking Out Poor Medical Students: S – superior thyroid artery A – ascending pharyngeal artery L – lingual artery F – facial artery O – occipital artery P – posterior auricular artery M – maxillary artery S – superficial temporal artery

Answer 79

*at or just posterior to the insertion of the rectus muscles; * At the corneoscleral junction (limbus); * At the site of previous surgical incisions. ie. Where the sclera is thinnest. Ie usually anterior to the equator Globe ruptures occur more often in the left eye, as a significant proportion are due to assault by a right-handed assailant.

Answer 80

Anterior chamber = 250micro litres Posterior chamber = 60 micro litres Vitreous body = 4ml Intraocular volume = 6.5ml

Answer 81

plate-based assay both qualitative and quantitative used to detect - antigen - antibody - peptides, - proteins - hormones. HIV It is highly sensitive and specific, although it may not detect a mutated antigen. Unlike radioimmunoassay, ELISA does not require the use of radioisotopes. Instead the antibodies (or antigens) are labelled with an enzyme (such as horseradish peroxidase) which induces a colour change in a substrate when present.

Answer 82

The human visual cycle involves phototransduction and the subsequent regeneration of visual pigment. 11-cis retinal (a chromophore) is covalently bound to opsins via a lysine residue on one of the transmembrane domains. Upon photon absorption, it undergoes photoisomerisation from 11-cis retinal to all-trans retinal, triggering the phototransduction cascade. All-trans retinal is converted to all-trans retinol in the photoreceptor outer segment before being transported to the retinal pigment epithelial cells, where it is reconstituted into the 11-cis retinal isoform (an isoform of vitamin A derived from carotenoids).

Answer 83

Actin is an important component of the cytoskeleton. It is a protein in the form of a microfilament, 7 nm in diameter, and can exist in monomeric and polymeric forms. Unlike microtubules, which are larger and rigid, actin is flexible. As well as providing structural support, actin is involved in cell motility, cell division, cell–cell interactions, contractility and the interaction of transmembrane and cytoplasmic proteins.

Answer 84

1 Muscles of mastication (masseter, pterygoids, temporalis); mylohyoid; tensor tympani; tensor veli palatini; anterior belly of digastric 2 Muscles of facial expression (surrounding the eye these include orbicularis oculi; corrugator supercilii; depressor supercilii; procerus and occipitofrontalis); stylohyoid; stapedius; posterior belly of digastric 3 Stylopharyngeus 4 Pharyngeal constrictors, levator veli palatini, cricothyroid 5 Intrinsic muscles of the larynx except cricothyroid

Answer 85

The sphenoid sinus normally develops two to three years after birth and reaches its adult size around age 14. The ethmoid and maxillary sinuses are usually present at birth, while the frontal sinuses, although occasionally present at birth, usually appear at around two years after birth. They continue to develop well into and even following puberty. The maxillary sinuses are the first sinuses to appear (usually at 3–4 months’ gestation) and are also the largest paranasal sinuses.

Answer 86

The hyaloid vasculature develops between the 3rd and 8th week along with the primary vitreous. From 18 weeks, the hyaloid vessels, the tunica vasculosa lentis and the primary vitreous begin to atrophy. As they regress, Cloquet’s canal is formed. Blood flow in the hyaloid artery stops at around 30 weeks, and by this point it has ceased to be visible on ultrasound. By 34–35 weeks it has lost its connection to the optic nerve and has essentially disappeared, though fragments can take longer to resorb entirely.

Answer 87

Macular dystrophy - aR disorder. Granular, lattice and Reis– Buckler dystrophies are all aD, resulting from mutations in the TGF-β-induced gene on chromosome 5q31 (as are Avellino dystrophy and Thiel–Behnke dystrophy).

Answer 88

b/l disease congenital - mutation at PAX6 on chromosome 11 a DOMINANT Ocular features include nystagmus, cataracts and foveal/optic nerve hypoplasia, with later complications including keratopathy and glaucoma. The commonest variant (approximately 70% of aniridia cases) is inherited in an autosomal dominant pattern, with no systemic associations. Of the smaller number of non-familial (sporadic) cases, 30%–50% are associated with nephroblastoma (Wilm’s tumour) due to deletion of the WT1 locus adjacent to PAX-6. Genitourinary malformations and mental retardation may also occur; this is sometimes referred to as WAGR syndrome (Wilm’s tumour–Aniridia–Genital anomalies–Retardation). A rare form of aniridia is Gillespie syndrome, which is usually autosomal recessive and associated with cerebellar ataxia.

Answer 89

The Hardy–Weinberg equilibrium describes the constancy of gene frequencies in a population from one generation to the next. For a gene with two alleles, it is expressed as: p2 + 2pq + q2 = 1 where p and q are the frequencies of the two alleles of a gene (i.e. p + q = 1). It only applies in randomly-breeding populations, in the absence of mutation, genetic drift and natural selection.

Answer 90

autosomal DOMINANT cancer syndrome mutation in the VHL gene on chromosome 3. Retinal angiomata (also known as capillary haemangiomata) are the cardinal ocular feature. These are visible on dilated fundoscopy, progressing from a small dot to a vascular mass. These can be treated with laser or cryotherapy and can cause retinal detachment. Cerebellar haemangioblastoma is also a cardinal feature of VHL but not an ocular one. Other non-ocular features include renal cell carcinomas and phaeochromocytomas.

Answer 91

Metacentric Submetacentric Acrocentric Holocentric Telocentric

Answer 92

account for 15% of serum proteins form an important immunological effector mechanism. most complement is produced by the liver, extrahepatic synthesis occurs in mononuclear phagocytes. The complement system functions as an enzyme cascade or series of zymogens. The classical cascade is triggered by antibody–antigen binding, and by acute phase proteins such as CRP. The alternative pathway is initiated by binding of C3b to factorB on the surface of an organism or foreign material. There are several regulatory mechanisms preventing inappropriate complement activity, including factor H and factor I (but not factor B), C1 inhibitor and sialic acid.

Answer 93

Coagulase indirectly promotes the conversion of fibrinogen to fibrin, which coats the surface of the bacterium and helps to isolate it from host defence mechanisms, including phagocytosis. The following promote bacterial spread. Streptokinase activates fibrinolysin and dissolves fibrin clots; hyaluronidase breaks down the extracellular matrix constituent hyaluronate; collagenase dismantles collagen.

Answer 94

The relative risk reduction (RRR) = (5/10) x 100 = 50% The absolute risk reduction (ARR) = 10% - 5% = 5%

Answer 95

Owl’s eye inclusion = CMV Cowdry type A inclusion bodies are nuclear = HSV, VZV Inclusion bodies can be detected on light microscopy in haematoxylin and eosin (H&E) stained preparations, and may be present in the cytoplasm (predominantly RNA viruses), the nucleus (generally DNA viruses) or both (as in cytomegalovirus).

Answer 96

Porro prisms -deviated 180degrees AND inverted -not transposed DOVE - inverted - not deviated or transposed Wollaston prisms - split an incident beam of light into two polarised emergent beams at a fixed angle without dispersion. Fresnel prisms - series of parallel small prisms of equal refracting angle which cause an equivalent prismatic effect to a single large prism of the same angle.

Answer 97

60 = 1.15 66 = 1.00 78 = 0.93 90 = 0.76

Answer 98

Air = 1 Aqueous/Vitreous humour/Water = 1.33 Cornea = 1.37 Lens = 1.38-1.41 Crown glass = 1.52

Answer 99

planoconcave lens used with the concave surface towards the patient. It has a power of –58.6 D forms a virtual, erect and diminished retinal image that lies within the eye of the patient but within the focal range of the slit lamp (usually in the pupillary plane when the lens is positioned close to the patient’s eye).

Answer 100

Fleischer rings = iron deposition in the basal epithelial layers at the base of the cone Kayser–Fleischer rings = copper deposition in Descemet’s membrane caused by Wilson’s disease and certain other hepatobiliary pathologies

Answer 101

mesenchymal cells Malignant tumours originating from have the suffix -SARCOMA, whereas benign mesenchymal tumours have the suffix -oma (compare liposarcoma: malignant with lipoma: benign). Similarly malignant tumours originating from the epithelial cells of surface tissues are denoted CARCINOMA (e.g. squamous cell carcinoma) and benign tumours are denoted papillomas (e.g. basal cell papilloma). Glandular epithelial cell tumours are called ADENOCARCINOMA if malignant and adenoma if benign. Tumours derived from neuroectodermal cells are generally malignant, with the notable exceptions of neurofibromas, ganglioneuromas and some meningiomas.

Answer 102

Epitheliod cells Monosomy 3 Partial duplication of 8q Old Large tumour size Extrascleral extension

Answer 103

* Degeneration of photoreceptors * Proliferation and migration of the retinal pigment epithelium * Subretinal recruitment of macrophage

Answer 104

type IV hypersensitivity reaction. Risk factors include: * Young age * Repeat grafts * Large grafts * Preoperative stromal vascularisation * Loose or broken sutures * Active inflammation

Answer 105

Atropine, cyclopentolate and ipratropium SE: dry mouth, tachycardia, palpitations, and urinary retention. The first two agents are common topical mydriatics and cycloplegics, whereas ipratropium is used as an inhaled bronchodilator. //Pyridostigmine is an inhibitor of acetylcholinesterase, used in the treatment of myasthenia gravis. It enhances rather than blocks acetylcholine activity at parasympathetic synapses.

Answer 106

CONVENTIONAL - via TM (pressure dependent) * trabecular meshwork to Schlemm's canal; * Schlemm's canal to collector channels and aqueous veins of Ascher; * collector channels and aqueous veins of Ascher to venous plexuses and conjunctival veins) e.g muscarinic agonist pilocarpine causes miosis and ciliary body contraction to open TM channels UNCONVENTIONAL - uveo-scleral flow e.g prostaglandin analogue e.g lantoprost BBlocker/Carbonic anhydrase inhibitors (e.g. dorzolamide) - reduce aqueous production AAgonist (e.g. brimonidine) - reduce aqueous production and increase aqueous outflow

Answer 107

Drusen is situated between the basement membrane of the RPE and the Bruch's membrane.

Answer 108

inferior division of the oculomotor (third) nerve —> nerve supplying the inferior oblique muscle ciliary ganglion; short ciliary nerve to innervate the sphincter pupillae.

Answer 109

Squamous cell carcinoma consists of squamous cells with prominent nuclei and abundant eosiophilic cytoplasm. BCC exhibits the pathognomonic palisading of cells at the periphery of the tumour.

Answer 110

NF Type 1 occurs from a mutation in the NF-1 gene on chromosome 17. It is characterised by: cafe-au-lait spots Lisch nodules goniodysgenesis retinal hamartomas optic nerve glioma phaeochromocytoma (nf1 and vhl) NOTE: B/L acoustic neuroma is associated with NF Type 2 but can also occur in NF1 ________ NF2 - chromosome 22 nearly all patients with NF2 will develop b/l acoustic neuromas before 30 meningioma

Answer 111

The EOG is an indirect measure of the standing potential of the eye. It depends on a normal retinal pigment epithelium. It requires co-operation of the patient who moves the eyes back and forth over a specific distance. The light response is higher than dark response. The result is given as a ratio between light to dark response. The normal ratio is more than 180%.

Answer 112

Luminous flux is the total light (or perceived light power) emitted from a source. It is measured in lumen (lm). Luminous intensity is the light emitted per unit solid angle; it is measured in candelas. Illumination/illuminance is a measure of the amount of light arriving at a surface. It is measured in lux, which measures luminous flux per unit area. Luminance is a measure of the amount of light emitted, reflected, or transmitted from a surface; luminance is measured in lamberts.

Answer 113

most common inherited cause of retinal detachment, most common cause of rhegmatogenous retinal detachment in childhood.

Answer 114

they are not as effective against systemic infection if given orally bind 30s subunit on ribosomes -> inhibits protein synthesis they act on messenger RNA they are NOT effective against streptococci or anaerobes as they require aerobic transport mechanisms to enter the bacterial wall

Answer 115

(1 - beta) is also called the power of a study. It is the probability of not accepting (i.e. rejecting) the null hypothesis when the alternative hypothesis is true. Put another way, it is the probability that if there is indeed a difference, that this difference will be found statistically.

Answer 116

The circle of least confusion in Sturm's conoid coincides with the focal point of the spherical equivalent of the toric lens.

Answer 117

This patient has hydrops caused by a rupture of Descemet's membrane with resultant corneal oedema and opacification. The initial therapy includes topical steroids, cycloplegics, and hypertonic saline drops. Once the condition has settled, scarring may occur and corneal transplantation may then be considered. Corneal transplantation should not be considered in the acute stage while the eye is inflamed.

Answer 118

120 million rods 6 million cones in the retina.

Answer 119

The chorda tympani is a branch of the nervus intermedius which in turn is a sensory component of the facial nerve. It contains: the parasympathetic nerve fibres that supply the salivary glands and the sensory nerve fibres that innervate the anterior two-third of the tongue. Anatomically, it passes between the internal jugular vein and internal carotid artery as it travels anteriorly. The greater petrosal nerve that contains parasympathetic nerve fibres to the lacrimal nerve exits the nervus intermedius at the geniculate body and therefore is not part of the chorda tympani.

Answer 120

I = SAFETY AND SE II = DOSING AND EFFICACY III= EFFICACY VS GOLD STANDARD IV = SURVEILLANCE - EFFECTIVITY AND SIDE EFFECTS

Answer 121

KIDS - 3500/mm2 ADULTS = 2500/mm2 ELDERLY = 2000/mm2

Answer 122

1. NODULAR well circumscribed clear peripheral palisading easily excised; 2. SUPERFICIAL appear as lobules localised to the dermal–epidermal junction; 3.INFILTRATIVE grow aggressively in strands with reduced peripheral palisading indistinct border; 4. MUTLINODULAR multiple small nodular aggregates of tumour. Both infiltrative BCCs and micronodular BCCs have an increased tendency for subclinical spread and caution should be taken to ensure clear margins.

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