George Winters - Eyes and Ears

Chalazion

Cysts of the sebaceous glands of a tarsal gland (Moll's gland anterior to the Meibomian glands) produces inflammation, a tarsal chalazion, that protrudes toward the eyeball and rubs against it as the eyelids blink.

Dopamine Pharmacology - parkinson's, receptors, drugs, synthesis breakdown

Dopamine 5 Dopamine receptors (D1-D5): G-proteincoupled receptors (GPCRs) · Strong link to: o Parkinson's disease (motor control - ↓ DA) o Schizophrenia/psychotic episodes (↑ DA) o Drug dependence o addiction, dependence and reward o Endocrine issues (breast swelling, galactorrhoea: dopamine inhibits prolactin release from pituitary gland) Dopamine Pharmacology Parkinson's Disease (PD) - Therapeutic approach is to increase synthesis of dopamine · Levodopa (L-DOPA) is used in PD (usually first line) · Co-administration of Carbidopa inhibits DOPA decarboxylase in the periphery thus diminishing peripheral side effects · L-DOPA in PD bypasses the rate controlling enzyme - Tyrosine Hydroxylase · Important side effects with Levodopa: o Dyskinesia: involuntary movements o Fluctuations in clinical state (on-off effect) o Schizophrenic-like syndromes o Nausea, vomiting, hypotension Dopamine synthesis and breakdown Tyrosine (by Tyrosine hydroxylase) -> L- DOPA (by DOPA decarboxylase) -> Dopamine (DA) (by DA β-hydroxylase) -> Noradrenaline Dopamine agonists e.g. bromocriptine, ropinirole · Fewer motor adverse effects but not as effective as L- DOPA · Often first drugs used for PD · Evidence of changes in behaviour patterns: excessive gambling, over-eating, sexual activity DA is broken down by two enzymes after neuronal uptake · Monoamine oxidase B (MAOB) in neurons · Catechol-O-Methyl Transferase (COMT) in neurons · Inhibition of dopamine breakdown used as a therapeutic strategy in PD MAOB inhibitors: e.g. selegiline · Act centrally to block dopamine breakdown · No cheese reaction (tyramine) · Used alone or with Levodopa COMT inhibitors e.g. entacapone · Adjunct to levodopa to manage on-off effect · Act primarily peripherally to block Levodopa breakdown

left hypoglossal nerve lesion

Examination will upon damage show an inability to stick the tongue out straight, and it will deviate towards the side with nerve damage. no change in taste.

Clinically Significant Macular Oedema (CSMO) (part of Diabetic Retinopathy)

Macular thickening with or without hard exudates as judged with stereobiomicroscopy; thickening can occur in various patterns: focal, multifocal, and diffuse areas of retina thickening Hard exudates (consisting of lipoproteins) in various patterns, e.g., circinate rings

route from hair cell to auditory cortex

Once the neurons of the auditory nerve depolarize, their axons head towards the brainstem. First, they enter the medulla on the same side of the body and synapse with neurons in the cochlear nuclei. From the cochlear nuclei, the electric impulse follows three different paths. In one path, the electric impulse crosses over and goes up to the inferior colliculus of the midbrain on the opposite side of the body. In a second path, the impulse also crosses over and goes up to the superior olivary nuclei of the pons on the opposite side of the body. And the third path goes straight to the superior olivary nuclei on the same side of the body. Then, from each superior olivary nuclei the impulse goes up to the inferior colliculus of the midbrain on the same side. Than goes to the medial geniculate nucleus of the thalamus, that sends the impulse to the auditory cortex in the temporal lobe—which include Brodmann's areas 41 and 42. Since the auditory pathway splits, some nerve fibers keep on the same side while others crossover, so the impulse reaches the auditory cortex on both sides of the brain - which then interprets the characteristics of the sound, giving us an idea of what we're listening to.

Causes of hearing impairment - Ototoxicity, Trauma, Tumours, Noise induced, Presbyacusis, Non-organic and Miscellaneous (=mixed, not spesifically genetic or aquiered)

Ototoxicity Aminoglycosides Loop diuretics Cytotoxic angents Beta blockers Salicylates Quinine Anticonvulsants Trauma • Temporal Bone Fractures • Barotrauma (diving) Tumours • External, Middle, Inner ear (Squamous cell) • Middle ear (glomus) • Cerebellopontine angle (Acoustic Neuroma, Meningioma, Cholesterol granuloma, arachnoid cyst, petrous apex cholesteatoma) • Central (space occupying lesions) Noise Induced Hearing Loss - causes damage to the hair cell (reversible or irreversible) Presbyacusis Age related hearing loss Progressive bilateral symmetrical SNHL Peripheral and central degeneration Reduction in outer and inner hair cells at basal cochlea Non-organic Hearing Loss • Apparent auditory deficit without true hearing loss • Adults • Children Miscellaneous (=mixed) • Central causes (CVA, MS, MND) • Autoimmune (SLE, Cogan's) • Endocrine (DM, hypothyroidism) • Chronic infections (syphilis, TB, sarcoidosis) • Endolymphatic hydrops (Meniere's) - characterized by episodes of feeling like the world is spinning (vertigo), ringing in the ears (tinnitus), hearing loss, and a fullness in the ear. Unclear cause.

Management of hearing loss - DDx according to location

Outer ear - wax, infection, exostosis Middle ear - Perforated ear drum, otitis media with effusion, otosclerosis Inner Ear - Presbyacusis, noise exposure, genetic, ototoxic Central - Dementia, depression

Colomboma

(Gr. kolomboma, meaning defect) is a hole in one of the structures of the eyem such as the iris, retina choroid, or optic disc. Most cases of coloboma affect only the iris.

Red Eyes causes

- Conjunctivitis - pink eye, inflammation of the conjunctiva. the thin layer above sclera - Sub-conjunctival Haemorrhage - bleeding from a small blood vessel in the conjunctiva into the space between the conjunctiva and the sclera. - HSV Keratitis - herpes simplex virus (HSV) infection in the cornea. - Corneal Ulcer - infection of the cornea involving disruption of epithelial layer with involvement of the corneal stroma (thickest layer of the cornea)

Neurological Eye Disease

- Discs • Papilloedema (optic disc swelling that is caused by increased intracranial pressure) •Optic atrophy (damage to the optic nerve) - Pupils & Ptosis •Horner's Syndrome - miosis (lesion of the sympathetic trunk) •Third Nerve Palsy / Oculomotor nerve palsy •All except Lateral Rectus & Superioi Obliqe •'Down and Out' •Ptosis -Levatorpalsy •Pupil Involvement •'Medical' v 'Surgical' causes movement - VI Nerve Palsy •Lateral rectus palsy •Can't abduct •Usually ischaemic

Retinal Detachment

- Fluid passes through tear - Retina gradually peels off - Growing peripheral shadow - Requires surgical repair • The 3Fs of retinal detachment • Flashes • Floaters • Field loss

Ocular Trauma

- Foreign Body • Corneal •Subtarsal (inner lid surface) •Intra-ocular (within the eye) - Corneal Abrasion (sacrach on the cornea) - Chemical Burn - Hyphaema - Penetrating Injury (bllod in the anterior chamber)

Rubeosis iridis Diabetic Retinopathy

- new vessel formation on the iris - usually occurs with retinal new vessels but can occur as an isolated feature - Difficult to treat - Often end stage disease - Leads to a very painful blind eye

Criteria for a Neurotransmitter

1. Must be present in nerves and must have machinery for synthesis and storage 2. Must be released by appropriate stimulation (calcium dependent) 3. Action of artificially applied substance must be identical to nerve stimulation and endogenous neurotransmitter release 4. Receptors must be demonstrable: drugs with known effects must affect the response in a predictable manner 5. A mechanism to terminate action must exist

Subjective Tinnitus - Epidemiology, Pathology, Aetiology

10 - 15% general adult population suffer from tinnitus 10 - 20% of these have symptoms severe enough to affect daily life pathology Disorder of the auditory system including the interpretation of auditory activity by the auditory cortex. Outer hair cell damage→ aberrant electrical discharge from neurons Electrical discharge can arise from cochlea, cochlear nerve, or neurons of the dorsal or ventral cochlear nucleus of the brain stem Multi-factorial symptom Not an organic disease »2/3 of affected pop. have hearing loss ❖90% Sensorineural hearing loss( SNHL) ❖5% Conductive hearing loss (CHL) ❖5% normal hearing Aetiology Disorders in the auditory system which may initiate tinnitus: - Injury: Petrous temporal bone fracture, NIHL, Ototoxicity - Infection: Viral cochleitis, bacterial labyrinthits - Tumours: Acoustic or facial neuromas, meningioma - Degeneration: Otosclerosis, Pagets - Vascular (arteriosclerotic disease) :diabetes, hypertension, anaemia - Meniere's disease exacerbate tinnitus: ❖Wax, foreign body in external ear ❖TMJ disorders ❖Malocclusion ❖Middle ear disease ❖Allergic rhinitis & sinusitis ❖Stress ❖depression

Weber's test

The test can detect unilateral conductive and sensorineural hearing loss. The outer and middle ear mediate conductive hearing. The inner ear mediates sensorineural hearing. The Weber test is often combined with the Rinne test to detect the location and nature of hearing loss. Weber Test Principles The inner ear is more sensitive to sound via air conduction than bone conduction (in other words, air conduction is better than bone conduction). In the presence of a purely unilateral conductive hearing loss, there is a relative improvement in the ability to hear a bone-conducted sound. This can be explained by the following: o Masking effect: The sound heard via the affected ear has less environmental noise reaching the cochlea via air conduction (for example, the environmental noise is masked) as compared to the unaffected ear which receives sounds from both bone conduction and air conduction. Therefore, the affected ear is more sensitive to bone-conducted sound. o Occlusion effect: Most of the sound transmitted via bone conduction travels through to the cochlea. However, some of the low-frequency sounds dissipate out of the canal. A conductive hearing loss (in other words, when an occlusion is present) will, therefore, prevent external dissipation of these frequencies and lead to increased cochlear stimulation and increased loudness in the affected ear. In the presence of sensorineural hearing loss, the sound will be perceived louder in the unaffected ear which has the better cochlear. Performing Weber Test Place the vibrating tuning fork on the vertex (other common sites used are the midline of the forehead, bridge of the nose, and chin), equidistant from both ears. These vibrations will be conducted through the skull and reach the cochlea. Ask the patient whether it is heard loudest in either one side or the midline (e.g., "Is the sound louder in your right ear, left ear, or the middle?") Interpretation Normal Hearing o Weber test does not demonstrate lateralization: In a normal subject, the sound should be heard in the middle and equally on both sides. o Rinne test: Normal/positive in both ears (AC greater than BC) Unilateral Sensorineural Hearing Loss o Weber test lateralizes to the unaffected ear, in other words, it is heard louder in the better ear. o Rinne test: Normal/positive on the affected ear (AC greater than BC); normal/positive on the unaffected ear (AC greater than BC) Note: an abnormal/negative response on the affected ear (BC greater than AC) can also occur in a severe sensorineural hearing loss, also called a dead ear. This is termed a "false negative." Rinne "true negative" only occurs if there is a conductive hearing loss element. However, when testing a dead ear, the bone conduction is perceived to be heard louder than air conduction due to cross-over of bone conduction detected by the opposite normal-functioning cochlear, resulting in a Rinne false negative. Unilateral Conductive Hearing Loss o Weber test lateralizes to the affected ear, in other words, it is heard louder in the poorer ear. o Rinne test: Abnormal/negative on the affected ear (BC greater than AC); normal/positive on the unaffected ear (AC greater than BC) Symmetrical Conductive Hearing Loss o Weber test does not demonstrate lateralization o Rinne test: Abnormal/negative on the affected ear (BC greater than AC)

Crystalline Lens

· Clear, flexible structure · Behind the iris & pupil · Surrounded by a ring of muscular tissue - ciliary body · The lens & ciliary body help control fine focusing of light as it passes through the eye (accommodation).

brainstem

the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions thalamous, mid brain, pons, medula,

Vitreous Detachment

the vitreous membrane separates from the retina - normal at older age - Causes 'Floaters' - Most cases asymptomatic

Rinne test

used to evaluate the loss of hearing in one ear. The Rinne test differentiates sounds transmitted by air conduction from those transmitted through the mastoid by bone conduction. It quick screens for the conductive hearing loss. Test Bone Conduction 1. Place the vibrating tuning fork on the mastoid process. 2. The patient should be asked to cover the opposite ear with their hand. 3. The patient should report when the sound can no longer be heard 4. Then move the vibrating tuning fork over the ear canal to the ear without touching it. 5. The patient should indicate when air conduction of the sound can no longer be heard. Normal finding: Air conduction should be better than bone conduction, and air conduction should persist twice as long as bone, this is a "positive test." Abnormal: Bone conduction is better than air conduction, this suggests conductive hearing loss and is referred to as "negative test."

Hyper(metr)opia

· 'Long sightedness' · Eyeball too short · Objects at all distances are focussed beyond the retina and thus blurred, near ones more than distant ones. · Small errors masked by lens accommodation. · Corrected with 'plus' or convex spherical lens

Presbyopia

· 'Old Sight' · Gradual loss with age of normal 'accommodation' i.e. the ability to increase curvature and power of lens to focus near objects · Corrected with +1 to +4D spherical lens just for near i.e. Reading Glasses. · If other refractive errors exist will need bifocals or varifocals.

The Choroid

· A layer of tissue located between sclera and retina, separating the retina & sclera · Mostly made up of blood vessels · Helps nourish the retina by carrying the blood supply to the eye's internal structures · Melanin helps the choroid limit uncontrolled reflection within the eye that would potentially result in the perception of confusing images

Structure and function of the iris

A. Iris dissected in situ. The iris separates the anterior and posterior chamber of the anterior segment of the eyeball as it bounds the pupil. B. Dilation and constriction of the pupil. In dim light, sympathetic fibers stimulate dilation of the pupil. In bright light parasympathetic fibers stimulate constricting the pupil.

Presbyacusis

Age related hearing loss Progressive bilateral symmetrical SNHL Peripheral and central degeneration Reduction in outer and inner hair cells at basal cochlea

Anatomy of the auditory system

Anatomy of the auditory system 1. External ear 1. Auricle 2. External acoustic meatus 3. Tympanic membrane 2. Middle ear . Tympanic cavity 1. Ossicles: malleus (touches the ™), incus, stapes (ends up oval window) 2. Muscles: tensor tympani and stapedius (sp?) - acoustic reflex 3. Epitympanic recess - where the incus and malleus articulate 1. Posterior to recess mastoid air cells, equalise when low pressure in middle ear, 4. Eustachian tube - connects middle ear to nasopharynx 3. Inner ear 1. Bony labyrinth 2. Vestibule (bit connects cochlea to semicircular canals) i.Cochlea (snail shell) 1. Semicircular canals ( three loops at 90 degree angles to each other) 1. Membraneous labyrinth (inside the bony labyrinth) 2. Cochlear duct - scala vestibuli (perilymph), cochlear duct (endolymph), scala tympani (perilymph) 2. Organ of corti - specialised endothelium 1. Inner and outer hair cells (translate vibration to neural signals) 3. Nerve signals auditory branch of CN VIII (vestibulocochlear nerve) back to auditory cortex in the temporal

Anterior chamber and Anterior chamber angle

Anterior chamber · Fluid-filled space · Behind the cornea, infront of the iris · Fluid = Aqueous humor (AH) (note that the aqueous humor is produced in the posterior chamber by the ciliary body) · AH helps nourish the cornea & the lens Anterior chamber angle · Located where the cornea meets the iris · Trabecular Meshwork = Site where aqueous humor drains out of eye · If AH cannot properly drain out o Pressure build up inside eye o Causes optic nerve damage & eventually vision loss = glaucoma · normal intraocular pressure ranges between 10-20mmHg

Serotonin (5-HT) Pharmacology - Drugs

Anti-depressants 1) Selective serotonin reuptake inhibitors (SSRIs) e.g. fluoxetine · Moderate-severe depression, panic disorder, obsessive compulsive disorder (OCD). Mechanism of action: inhibits re-uptake into pre-synaptic terminals and increases synaptic cleft 5-HT. Safer in overdose 2) Serotonin noradrenaline reuptake inhibitors e.g. venlafaxine · Moderate-severe depression. Generally second line to SSRIs, also inhibit reuptake of noradrenaline. 3) Tricyclic antidepressants (TCAs) e.g. amitriptyline · Moderate-severe depression, neuropathic pain. 5-HT and noradrenaline reuptake inhibitor. Dangerous in overdose. 4) MAOIs e.g. phenelzine (mixed), moclobemide (MAOA selective) · Generally used after other treatment modalities have failed. Cheese reaction (less with moclobemide, cause hypertension attack when digesting tyramine rich food like chesse) Other Drugs Agonists · 5HT1D/1B agonist - Sumatriptan - treatment of migraine headache · 5-HT1A- partial agonist - Buspirone - anxiolytic Antagonist · 5-HT3 - Ondansetron - anti-emetic particularly in cancer chemotherapy · 5-HT2 - atypical antipsychotics

Increased Dopamine: Psychosis, schizophrenia - Drugs

Anti-psychotic effect Strong correlation between raised DA levels and schizophrenia Typical anti-psychotics: chlorpromazine, haloperidol · Selective D2 (<D1) antagonists · Side effects: extrapyramidal side effects, hyperprolactinemia · Extrapyramidal side effects: acute dystonias (repeated muscle movement) and tardive dyskenisia (involuntary muscle movements) Atypical antipsychotics: e.g. olanzapine, clozapine · 5-HT2 receptor antagonists (and D2) · Less extrapyramidal side effects

Hordeolum (or Sty)

Any of the glands in the eyelid may become inflamed and swollen from infection or obstruction of their ducts. If the ducts of the ciliary glands (Meibomian glands on the tarsal plain in the eyelid secreat oil that protects the eye) are obstructed, a painful red suppurative (pus-producing) swelling a sty (hordeolum) develops in the eyelid. The cause of a sty is usually a bacterial infection by Staphylococcus aureus.

Aqueous humor drainage

Aqueous humor (provides nutrients and structural support) secreted by the ciliary epithelium into the posterior chamber, and then flows through a narrow space between the front of the lens and the back of the iris through the pupil to the anterior chamber. From there the fluid flows out of the eye through the trabecular meshwork, which is a spongy tissue that acts like a drain, and this allows the fluid to go down into a circular channel called the canal of Schlemm and finally into aqueous veins that are part of the episcleral venous system—the veins around the sclera of the eye. From PBL: Aqueous humor synthesis 1. Epithelial cells of the ciliary body- Na + HCO3- 2. Posterior chamber (Behind the Iris) 3. Moves to the anterior chamber (in front of the Iris) 4. Iridocorneal Angle (angle that iris and the cornea) 5. Trabecular meshwork (creates the intraocular pressure we see in the eye (10-20mmHg)) 6. Canal of Schlemm 7. Aqeuous veins 8. Episcleral veins

Staging of Diabetic Retinopathy - Background

Background Diabetic Retinopathy - dot & blot haemorrhages (microaneurysms& small deep intra-retinal bleeds) - flame shaped haemorrhages (retinal surface haemorrhages) - exudates (true exudates)

Categories of hearing loss

CONDUCTIVE HEARING LOSS Conductive hearing loss can occur when there is damage or a blockage in the outer and/or middle ear. This can result in sound not being conducted adequately through the ear canal to the eardrum, or from the eardrum via the ossicles of the middle ear to the inner ear. It can be caused by earwax, a perforated eardrum, a buildup of fluid in the middle ear from a cold or flu, (often referred to as 'glue ear'), abnormal bone growth involving the ossicles, repeated ear infections and allergies. It is more common in children and indigenous populations. Medical interventions and technologies are often used to treat conductive hearing loss. SENSORINEURAL HEARING LOSS Sensorineural hearing loss occurs when there is damage or malfunction of the hair cells in the cochlear. Sensorineural hearing loss is the most common type of permanent hearing loss. Assistive technologies can help reduce the effects of sensorineural hearing loss. MIXED HEARING LOSS A mixed hearing loss occurs when both conductive and sensorineural hearing losses are present. The sensorineural component of the hearing loss is permanent, while the conductive component may be permanent or temporary. AUDITORY NEUROPATHY Auditory Neuropathy occurs when there is a problem with the auditory nerve transmitting the signal from the cochlea to the brain. The hearing loss can vary from normal to profound and hearing levels may fluctuate. Understanding speech in background noise can be a particular difficulty. The cause of auditory neuropathy includes lack of oxygen or jaundice at birth, or some neurological conditions. Assistive technologies can usually help reduce the effects of auditory neuropathy.

CSF

CSF ROLE 1. Buoyancy 2. Protection 3. Chemicalstability Cerculation Produced from choroid plexus -> lateral ventricles -> foramina of Monro -> 3rd ventricle -> cerebral aqueduct of Sylvius -> 4th ventricle (in the brainstem) -> central canal of the spinal cord or into the subarachnoid space via 3 foramina (central = Magendie, lateral x2 = Luschka) -> reabsorbed via the arachnoid villi in the venous system -> superior sagittalsinus

Cataracts - definition, causes, types and trearment

Cataract A cataract is a clouding (opacification) of the lens in the eye which leads to a decrease in vision, Glare from lights, Poor night vision and Increasing myopia (near-sightedness). Commonest cause of blindness 20m (out of ~45m blind) Mostly affects old people Causes: · Age · Diabetes · Drugs - especially Steroids · Trauma · Eye disease and surgery · Congenital/Inherited There are no preventative measures TYPES · Nuclear o Opacification of lens nucleus o Slow progression of vision loss · Cortical o Opacification of lens fibers surrounding nucleus (cortex) o Mild degradation of vision · Posterior subcapsular (back of the lens) o Opacification in posterior cortical layer under lens capsule o Rapid progression · congenital cataracts (born with). born cataract or developed during childhood. These cataracts may be genetic or associated with an intrauterine infection or trauma. Surgical removal is the only treatment · removing the clouded lens and replacing it with a clear artificial lens · if cannot use of an artificial lens. Removing the lens and leaving the capsule intact. vision may be corrected with eyeglasses or contact lenses. · 98%+ Success Rate · Serious Complications Rare · 1 in 1500 Endophthalmitis (inflammation of vitreous and aqueous humor)

Treatment for general hearing impairment

Cause dependent treatment o hearing aids including Bone Anchored Hearing Aid o fm systems (wireless assistive hearing devices that enhance the use of hearing aids) like roger pen - transmits the signal automatically through high-quality sound and is able to connect via Bluetooth to cell phones and other audio inputs for listening to TV and multimedia. o cochlear implants

Causes of hearing impairment - Genetic and related to birth

Causes of hearing impairment Congenital Acquired Genetic Non-Genetic Genetic Dysplasia: Michel's Mondini's - a cochlea with incomplete partitioning and a reduced number of turns, an enlarged vestibular aqueduct and a dilated vestibule. A normal cochlea has two and a half turns, a cochlea with Mondini dysplasia has one and a half turns. Bing-Siebenman Scheibe Genetic Syndromic: Autosomal Dominant • Treacher-Collins - genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. • Waardenburg - genetic condition characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or one blue eye and one brown eye), a white forelock or patches of light skin. • Pierre-Robins • Crouzon • Apert Genetic Syndromic: Autosomal Recessive • Usher • Pendred • Jervell and Lange-Nielson - type of long QT syndrome associated with severe, bilateral sensorineural hearing loss. • Branchio-oto-renal Genetic: X linked Alport's syndrome - characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. Genetic mitochondrial Maternal Aminoglycoside ototoxicity Down's syndrome Small auricles narrow ear canals malfunctioning ETs Ossicular malformations Sensorineural deafness (8%) Genetic: Non-Syndromic Deafness • DFNA, DFNB --> Locus • GJB2 --> Gene • Connexin 26 --> Protein • Auditory Neuropathy • OTOF (Otoferlin) Pre-natal • Intrauterine infections (TORCH) - TORCH syndrome is a cluster of symptoms caused by congenital infection with toxoplasmosis, rubella, cytomegalovirus, herpes simplex, and other organisms including syphilis, parvovirus, and Varicella zoster. • Ototoxic drugs - listed below. • Metabolic disorders (maternal diabetes) Peri-natal Prematurity Low Birth Weight Hypoxia · Hyperbilirubinaemia Post-natal • Bacterial Meningitis • Other infections ‣ mumps ‣ measles ‣ CMV ‣ middle ear Complications of otitis media - a group of inflammatory diseases of the middle ear.

Cerabellum lesions, Ceribral lesions

Cerabellum lesions - ipsilateral, symptoms in the same side of the body Ceribral lesions - contralateral, Symptoms on th oppiset side of the body

Diabetic retinopathy - epidemiology and incidance

Commonest cause of blind registration in the working age group Diabetic eye disease varies according to • age when diabetes started • duration of diabetes • type of diabetes Epidemiology of diabetic retinopathy GLOBAL PREVALENCE OF DM 463M (9.3%) BY 2045 THIS WILL INCREASETO700M (10.9%) 30% of diabetics will have diabetic eye disease 10% of diabetics will have diabetic eye disease that threatens their sight Incidence of Diabetic Retinopathy 5 -10 years 27% >10 years 71% >30 years 90%

Causes of hearing impairment - Spesific to location

External Ear Conditions • Foreign body • Infections (Otitis Externa - Otomycosis) • External Canal Stenosis (Exostosis - Osteoma) • Wax • Tumours Tympanic Membrane Abnormalities • Perforation - tear • Tympanosclerosis - hyalinization and subsequent calcification of subepithelial connective tissue of TM and middle ear, sometimes resulting in a detrimental effect to hearing. • Atelectasis - a part of the TM is deeper Middle Ear Conditions • Glue ear (Otitis Media with effusion) • Otosclerosis - spongy bone replace part of normally dense enchondral layer of bony otic capsule in the bony labyrinth (bony outer wall of the inner ear in the temporal bone). • Acute Otitis Media (infection of the middle ear) • Chronic Otitis Media (with or without Cholesteatoma) • Ossicular chain disruption (Otosclerosis, ossicular dislocation, Paget's, osteogenesis imperfecta) • Cholesteatoma - destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process • Tumours (glomus) - benign

Muscles of the eye and their innervation and action

Extraocular muscles · 6 extraocular muscles that are attached to each eye · Help move the eye left, right, up, down and diagonally · These 6 muscles are: o Superior rectus o Inferior rectus o Medial rectus o Lateral rectus o Inferior oblique o Superior oblique · Innervated by CN IV (4, trochlear - sup oblique), CN VI (6, abducens - lateral rectus) and CN III(3, oculomotor - all the other muscles) Recti Muscles There are 4 recti muscles; superior rectus, inferior rectus, medial rectus and lateral rectus. These muscles characteristically originate from the common tendinous ring. This is a ring of fibrous tissue, which surrounds the optic canal at the back of the orbit. · Superior Rectus o Attachments: attaches to the superior and anterior aspect of the sclera. o Actions: Main movement is elevation. Also contributes to adduction and medial rotation of the eyeball. o Innervation: Oculomotor nerve (CN III). · Inferior Rectus o Attachments: attaches to the inferior and anterior aspect of the sclera. o Actions: Main movement is depression. Also contributes to adduction and lateral rotation of the eyeball. o Innervation: Oculomotor nerve (CN III). · Medial Rectus o Attachments: attaches to the anteromedial aspect of the sclera. o Actions: Adducts the eyeball. o Innervation: Oculomotor nerve (CN III). · Lateral Rectus o Attachments: attaches to the anterolateral aspect of the sclera. o Actions: Abducts the eyeball. o Innervation: Abducens nerve (CN VI). Oblique Muscles From their origin, the oblique muscles take an angular approach to the eyeball (in contrast to the straight approach of the recti muscles). They attach to the posterior surface of the sclera. · Superior Oblique o Attachments: Originates from the body of the sphenoid bone. Its tendon passes through a trochlear (c.nerve 4), and then attaches to the sclera of the eye, posterior to the superior rectus. o Actions: Depresses, abducts (to lateral side) and medially rotates the eyeball. o Innervation: Trochlear nerve (CN IV). · Inferior Oblique o Attachments: Originates from the anterior aspect of the orbital floor. Attaches to the sclera of the eye, posterior to the lateral rectus. o Actions: Elevates, abducts and laterally rotates the eyeball. o Innervation: Oculomotor nerve (CN III).

GABA Pharmacology - use, Synthesis and Breakdown, Drugs

GABA Pharmacology Synthesis and breakdown Glutamate is synthesized from: · Glutamine · Glucose - via Krebs cycle GABA is synthesized from: · Glutamate via glutamic acid decarboxylase (GAD) · This enzyme is found in GABAergic neurons (referring to GAD) So changes in glutamate levels can potentially alter GABA GABA Pharmacology · GABA is the major inhibitory neurotransmitter in the CNS o GABAA: ligand-gated ion channel o GABAB: GPCR · No GABAA agonists or antagonists in medical use · Benzodiazepines potentiate the effects of GABA at GABAA anxiolytics (for enxiety, sedative/hypnotics, anticonvulsants o Examples: diazepam, lorazepam · Selective sedative/hypnotics: Zolpidem, Zopiclone potentiate the effects of GABA at GABAA receptors

Objective Tinnitus

Generated by internal body sounds May be caused by: ❖tumors ❖Turbulent flow through malformed vessels ( a-v malformations), ❖or rhythmic muscular spasms (Palatal myoclonus) Managed by treating the cause.

Glaucoma - definition, types and treatment

Glaucoma: If the outflow of aqueous humor decreases significantly because the outflow pathway is blocked, pressure builds up in the anterior and posterior chambers of the eye, a condition called glaucoma. Cause: drainage system is blocked leading to intraocular hypertension Pressure · Normally < 21mmHg in glaucoma >21mmHg. Effect many structures in the eye including the optic nerve and over time leading to vision loss. · Measured by 'Tonometry' · Opticians use a 'puff of air' · We use 'applanation' (the device where you put your chin, then a flat-tipped cone that gently comes into contact with your cornea) Visual Fields · Measured by perimetry · Typical arcuate defects · Gradual so unnoticeable to patient Types: Glaucoma - Acute (Closed Angle) The angle between the iris of the cornea being too small, meaning that the passageway for aqueous humor outflow is too narrow, and this is as a result of the lens being pushed up against the iris. Access to drainage is limited (smaller). · Mechanical closure of the angle · Acute rise in IOP (50+ mmHg over a few hours) · Painful red eye · Haloes around lights · Acute loss of vision · Nausea +/-vomiting · On examination - Red eye, Fixed pupil and Cloudy cornea · Patients will blind within hours Glaucoma - Chronic (Open Angle) - Affects 2-3% over 40 the angle between the cornea and the iris is "open." The drainage system gets clogged over time. · Progressive damage to retinal nerve fibres · Progressive loss of peripheral vision and eventually central vision loss as well. · Lifetime treatment with pressure lowering drops · May need surgery if drops not effective · Patients unaware so screening is vital · End stage 'tunnel vision' and blindness - irreversible Screening: go to GP or optician if there is concern about the vision Diagnosis of glaucoma, tonometry (light touch...) can be used to assess for increased intraocular pressure. Also visual field testing can be done, as well as looking for optic nerve damage either through imaging or by direct observation. That pressure on the optic nerve results in a thinning of the outer rim of the nerve, which starts to give it this cup-shape, and this is called "cupping" and it's often seen in individuals with glaucoma. Treatment: managed by taking medications that decrease the pressure in the eye. · decreasing the production of aqueous humor - beta-adrenergic receptor antagonists and carbonic anhydrase inhibitors. · increase the outflow of aqueous humor - prostaglandin analogs · both decrease production and increase outflow - alpha adrenergic agonists. laser treatments · trabeculoplasty is a treatment where a laser is used to open the trabecular mesh network and this helps treat open angle glaucoma. · iridotomy, which uses a laser to punch a tiny hole in the iris which helps treat closed angle glaucoma. · Another laser treatment - destroying the humor-producing cells, which reduces production of the fluid and in serious cases can be used to create a new channel through which the aqueous humor can be drained out. implants - shunt fluid out of the anterior chamber by bypassing the trabecular meshwork and collecting system.

Glutamate Pharmacology - receptors, physiological use

Glutamate Pharmacology · Major excitatory neurotransmitter in the CNS o Ligand-gated receptors § NMDA, AMPA, kainate - Na/Ca influx o G-protein coupled receptors - mGlu · Stimulation of these postsynaptic receptors: activate nerve cells - more firing Glutamate Pharmacology Physiological role: · Synaptic plasticity - basis for learning/memory · Excitotoxicity - glutamate may actually be toxic to nerves · Needs to be quickly taken up by glia cells · Excess release of glutamate, e.g. stroke Huge pharmacological potential, But: potential for huge side effects Ketamine: non-competitive block at NMDA - Used in anaesthesia, recreational

Damage to the visual pathways will lead to various damage.

Hemianopsia, or hemianopia, is a loss of vision or blindness (anopsia) in half the visual field.

neural pathways of the iris (Pupillary light reflex)

In dim light, sympathetic fibres stimulate dilation of the pupil (mydriasis, expansion). In bright light parasympathetic fibres stimulate constricting the pupil (miosis/myosis). Pupillary light reflex Photosensitive retinal ganglion cells è optic nerve è pretectal nucleus of the upper midbrain (instead of the cells of the lateral geniculate nucleus which project to the primary visual cortex). Part of the innervation here crosses over (consensual reflex) è Edinger-Westphal nucleus. è oculomotor nerves è Ciliary ganglia è Iris sphincter muscle of the iris From PBL: Innervation of the iris: CNII/V Retina -> CN II -> prerectal N. -> EW nucleus -> CN III -> ciliary sphincter

Tinnitus - Definition

Is hearing sounds which do not originate from an external source Described as ringing, buzzing or other 2 types: Objective - patient, doctor & others hear sound Subjective- most common, only patient hears the sound

Accommodation reflex

It comprises of coordinated changes in vergence (simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision), lens shape (accommodation) and pupil size. The change in the shape of the lens is controlled by the ciliary muscles inside the eye. The reflex, controlled by the parasympathetic nervous system, involves three responses: pupil constriction, lens accommodation, and convergence (to become a single point). Information from the light on each retina is taken to the occipital lobe via the optic nerve and optic radiation (after a synapse in the lateral geniculate body of the posterior thalamus), where it is interpreted as vision. The peristriate area 19 interprets accommodation and sends signals via the Edinger-Westphal nucleus and the 3rd cranial nerve to the ciliary muscle the medial rectus muscle and (via parasympathetic fibres) the sphincter pupillae muscle. From PBL: Definition: when the lens change how they refract light to focus on objects that are far away/closer. Neural pathway: Retina (input) -> CNII (optic nerve) -> LGN -> Optic Radiation -> Primary Visual Cortex (Occipital Lobe) ->EW nucleus -> CNIII (Occulomotor) -> Ciliary muscle change

Diabetic retinopathy treatment

Laser photocoagulation - laser burns are made on the retina to target leaking blood vessels or treat the peripheral retina to slow the growth of new abnormal vessels Vitrectomy surgery to remove some or all of the vitreous humor from the eye, removal of scar tissue indications: • vitreous haemorrhage (the blood will be removed) • tractional retinal detachment Anti vascular endothelial growth factor (VEFG) antibodies (injection) - Block leakage - Regress neovascularization - BUT - Expensive and Need monthly injections

Retinal Detachment -treatment

Pneumoretinopexy / Pneumatic retinopexy injection of gas bubble into the eye to push the retina to the back of the eye. then freezing the retina in place.

Staging of Diabetic Retinopathy - Pre-proliferative

Pre-proliferative Diabetic Retinopathy - venous engorgement and segmentation - venous loops - large intra-retinal haemorrhages - multiple cotton wool spots - exudates

Staging of Diabetic Retinopathy - Proliferative

Proliferative Diabetic Retinopathy - new vessel formation at the disc - new vessel formation elsewhere - If not treated: fibrosis of the retina with retinal detachment

Audiometry

Pure tone audiometric air conduction testing is performed by presenting a pure tone to the ear through an earphone and measuring the lowest intensity in decibels (dB) at which this tone is perceived 50% of the time. This measurement is called threshold. The testing procedure is repeated at specific frequencies from 250 to 8000 hertz (Hz, or cycles per second) for each ear, and the thresholds are recorded on a graph called an audiogram. Hearing loss is often described as follows: o Normal = less than 25 db HL o Mild = 25-40 db HL o Moderate = 41-65 dB HL o Severe = 66-90 db HL o Profound = more than 90 db HL To prevent crossover of sound from one ear to the other, narrow band noise is presented to the non-tested ear and thresholds are recorded as masked.

Posterior chamber of the eye

· A narrow space behind the peripheral part of the iris, and in front of the suspensory ligament of the lens and the ciliary processes. · Fluid-filled space (Aqueous Humor is produced here) · Immediately behind the iris but infront of the lens

Serotonin (5-HT) Pharmacology - use, receptors type, synthesis and breakdown

Serotonin (5-HT) Pharmacology Correlation of low 5-HT levels and mood disorders o 14 5-HT receptors! § 13 GPCRs § 1 ligand-gated ion channel o Multiple functions - Behavior, mood, sleep, feeding, analgesia Serotonin (5-HT) Pharmacology Synthesis and Breakdown Synthesis Tryptophan (dietary) [by Tryptophan hydroxylase turn to] -> 5-hydroxytryptophan (5-HTP) [by 5-HTP decarboxylase turn to] -> 5-hydroxytryptamine (5-HT) Breakdown 5-HT [by MAOA turn to] -> 5-hydoxyindoleacetaldehyde (5-HIA) [by Aldehyde Dehydrogenase (AD) turn to] -> 5-hydoxyindoleacetic acid (5-HIAA)

Physiology of hearing

Sounds are vibrations of the air. These vibrations captured by the auricle are routed into the external auditory canal. They are then transmitted from the tympanic membrane to the ossicles (the malleus to the incus, and from the incus to the stapes. The foot of the stapes rests on the oval window - and since the oval window is about 20 times smaller than the eardrum, so the sound waves are amplified) and reach the cochlea in the inner ear. The cochlea is formed by three parallel coiled canals: the cochlear canal, the tympanic ramp, and the vestibular ramp. Sonar vibrations enter the cochlea via the vestibular ramp. As they travel, they stimulate the organs of corti, which transform the vibratory movement into nerve impulses by the hair cells. These impulses are transmitted by the cochlear nerve to the cerebrum, where the sounds are analyzed in the auditory cortex. extra point: the cochlear duct ends right below the tip of the cochlea, leaving an opening called the helicotrema right above - so the scala vestibuli and the scala tympani communicate with each other through the helicotrema.

Subjective Tinnitus - Signs and Symptoms

Symptoms ❖Constant/intermittent, low or high pitch sounds ❖Non pulsatile ❖+/- hearing loss ❖precipitated by stress or adverse life event Signs ❖None ❖Patient distress ❖abnormal audiogram ❖abnormal sensitivity to loud sounds

Anatomy of the eye: boney borders

The borders and anatomical relations of the bony orbit are as follows: · Roof (superior wall) - Formed by the frontal bone and the lesser wing of the sphenoid. The frontal bone separates the orbit from the anterior cranial fossa. · Floor (inferior wall) - Formed by the maxilla, palatine and zygomatic bones. The maxilla separates the orbit from the underlying maxillary sinus. · Medial wall - Formed by the ethmoid, maxilla, lacrimal and sphenoid bones. The ethmoid bone separates the orbit from the ethmoid sinus. · Lateral wall - Formed by the zygomatic bone and greater wing of the sphenoid. · Apex - Located at the opening to the optic canal, the optic foramen. · Base - Opens out into the face and is bounded by the eyelids. It is also known as the orbital rim.

the eye refractive power

The cornea provides 2/3rds of the refractive power of the eye (~40 diopters). The lens provides about 1/3rd of the refractive power of the eye (~20diopters).

Blood supply of the Eye

The eye receives blood primarily from the ophthalmic artery. Venous drainage is via the superior and inferior ophthalmic veins.

Sudden Visual Loss causes

Think 'Vascular Event' • Retinal vein or artery occlusion • IschaemicOptic Neuropathy • Vitreous Haemorrhage Think of systemic associations • Hypertension • Diabetes • Hypercholesterolaemia • Hyperviscosity syndromes • Giant Cell Arteritis

Treatment and Management of tinnitus

Treatment o Underlying cause o Hearing aids, noise generators, antidepressants, life-style modifications o Relaxation training, stress management, cognitive therapy, tinnitus retraining therapy (directive counselling & habituation) o Acoustic desensitisation: enrichment of patient's sound environment, during the quietest periods of day or night, & use of wearable noise generator, starting at a just audible level and later increasing gradually over weeks or months Management ❖Investigation where indicated and treatment as indicated ❖Advice and reassurance ❖Sound enrichment ❖Relaxation/Stress reduction techniques ❖Consider referral to audiology/hearing therapy ❖Hearing aids

visual acuity, interpret snellen chart results, color vision assesment

Visual acuity is a number that indicates the sharpness or clarity of vision. A visual acuity measurement of 20/70 means that a person with 20/70 vision who is 20 feet from an eye chart sees what a person with unimpaired (or 20/20) vision can see from 70 feet away. How to asses colour vision: The Ishihara Color Vision Test is the color blindness test. There are dots of varying brightness, colors, and sizes. If you have normal color vision, you will be able to pick out the number that is present among the dots.

When rods and cones are activated ...

When rods and cones are activated, they hyperpolarize (turn off, stop releasing neurotransmitters) and create an action potential, which triggers depolarization of the bipolar cells, which then triggers the depolarization of the ganglion cells. The action potential in the ganglion cells travels through their axons to the posterior portion of the retina to form the optic nerve, which leaves the eye through the optic disc medial to the macula. Light goes all the way back and excite the rods / cons or absorbed by pigmented epithelium.

Visual Axis

direction of gaze. A straight line that passes from an object through the centre of the lens and the centre of the fovea (the area of most acute vision in the macula)

Tonsils herniation

due to high intercranial pressure the cerebellar tonsils move downwards through the foramen magnum causing compression if the medulla oblongata and upper cervical spinal cord. increased pressure in the posterior fossa may cause cardiac and respiratory dysfunction loss of consciousness (RAS) focal lower cranial nerve dysfunction (pupillery light reflex and vertical eye movement)

3 layers of the eye

fibrous (sclera, cornea), vascular (iris, pupile, ciliary body - hold the lens, chorid - contain blood vessels provie nutrients, dark color absorb light), sensory (neural, rods and cons)

lobes of the brain

frontal, parietal, occipital, temporal

Emmetropia

having no significant refractive error and thus normal vision without spectacles

Keratitis

inflammation of the cornea

Optical Axis

line drawn through the centre of the cornea, the center of pupile and the nodal (central) point of the eye (devide the eye in two)

Organ of Corti

made up of mechanosensory cells called hair cells, that have 30 to 300 finger-shaped projections called the stereocilia - which are like hair - on the top or apical end. At the opposite side - or the basal end of the cell - there's the presynaptic membrane, which is close to the cranial nerve. The hair cells are arranged in rows, one row of inner hair cells - closer to the modiolus, and three to five rows of outer hair cells - closer to the spiral ligament. Inner hair cells are innervated mainly by sensory nerve fibers, so they're the ones in charge of auditory transduction. Outer hair cells, on the contrary, are innervated mainly by motor nerve fibers that carry signals from the brain, and they contract and stretch in response to these signals - which changes the stiffness of the basilar membrane in order to intensify or minimize the auditory signal, to help us hear a whisper, or protect our inner ear from damage during a blasting rock concert. The tips of the stereocilia are embedded in the tectorial membrane - which is a gelatinous membrane attached to the modiolus at one end and free at the other end - so like a flap. So when the basilar membrane vibrates, it actually pushes the organ of Corti and the hair cells up against the tectorial membrane. The apical end of the cell - near the endolymph - has stereocilia, and at the tip of each stereocilium, there is a protein filament - called a tip link - attached. The tip link attaches to two things, one of them is the membrane of a particular stereocilium, and the other is a mechanically gated potassium channel in the membrane of another, longer stereocilium in the next row. When the hair cells move towards the tectorial membrane, the shorter stereocilia bend towards the longer ones and the tip link opens the potassium channel. The potassium concentration is higher in the endolymph than inside the cells, so when the potassium channel opens, potassium ions enter the hair cell in the apical end, and the cell membrane depolarizes. At the opposite side of the cell - or the basal end - there's the presynaptic membrane, which is close to the cranial nerve. Depolarization goes all the way to the presynaptic membrane, where it causes voltage-gated calcium channels to open. Calcium ions then enter the cell and that triggers vesicles in the cytoplasm that are filled with glutamate to be released into the synaptic space.

Neurotransmitters - Names

· Acetylcholine · Monoamines - Serotonin (5-HT), Dopamine and Noradrenaline · Histamine · Amino acids - Glutamic acid, γ-aminobutyric acid (GABA) and Glycine · Neuropeptides - Opioid peptides, Vasoactive Intestinal Peptide (VIP) and Neuropeptide Y

Tympanometry

measures the function and movement of the eardrum and middle ear. The tympanometer causes the air pressure in your ear canal to change as you hear a low-pitched tone. The feeling is similar to the pressure changes felt during take-off and landing when you're on a plane. While the pressure is changing, measurements of your eardrum's movement will be taken and recorded. The instrument changes the pressure in the ear, generates a pure tone, and measures the eardrum responses to the sound at different pressures. This produces a series of data measuring how admittance varies with pressure, which is plotted as a tympanogram. Result could be normal, shoe fluid in the middle ear or perforation of the tympanic membrane or patent pressure equalization tube (if the line is flat), a tumor in the middle ear (if the chart is not in the middle above 0 but above a different number - deviated).

cisterna magna

one of three principle openings in the subarachnoid space between the arachnoid and pia mater layers of the meninges surrounding the brain. The openings are collectively referred to as the subarachnoid cisterns. The cisterna magna is located between the cerebellum and the dorsal surface of the medulla oblongata.

Diplopia

simultaneous perception of two images of a single objec

Visual pathways

· Conveyance of visual information to occipital cortex · Notice that peripheral visual information (from the temporal fields) crosses over to be processed by the opposite hemisphere · Information from the nasal fields stays on the same side. A Origin, course and distribution of visual pathway. Axons of retinal ganglionic neurons convey visual information to the lateral geniculate body (LGB) of thalamus through the CV II and optic tract. Fibers from the LGB project to the visual cortices of the occipital lobes. B The visual pathway with photoreceptor cells (rods and cones) in the retina. 1st neuron = rods and cones to 2nd neuron = bipolar cells to 3rd neuron = ganglion cells (optic nerv) to 4th neuron = optic radiation

Astigmatism

· Cornea more steeply curved in one direction than another · Rugby ball v football · Things cannot be focussed clearly at any distance · Corrected with cylindrical lens (convex or concave on one side and straight on the other)

Optic nerve - Optic Disc

· Cranial nerve II · A bundle of 1 million nerve fibers · Responsible for transmitting nerve signals, visual information, from the eye (retina) to the brain · The optic disc is the front surface of the optic nerve (visible on the retina) · It is the point of exit for ganglion cell axons leaving the eye. · There are no rods or cones overlying the optic disc so it corresponds to a small physiological blind spot in each eye. · Represents the beginning of the optic nerve · Entry point for the major blood vessels that supply the retina

How a loss of parasympathetic innervation causes ptosis (drooping) of the eyelid? Levator Palpebrae Superioris

· Levator Palpebrae Superioris The levator palpebrae superioris (LPS) is the only muscle involved in raising the superior eyelid. A small portion of this muscle contains a collection of smooth muscle fibres - known as the superior tarsal muscle (also known as Müller's muscle). In contrast to the LPS, the superior tarsal muscle is innervated by the sympathetic nervous system. · Attachments: Originates from the lesser wing of the sphenoid bone, immediately above the optic foramen. It attaches to the superior tarsal plate of the upper eyelid (a thick plate of connective tissue). · Actions: Elevates the upper eyelid. · Innervation: The levator palpebrae superioris is innervated by the oculomotor nerve (CN III). The superior tarsal muscle (located within the LPS) is innervated by the sympathetic nervous system.

Vitreous chamber

· Located behind the lens & in front of the retina · Filled with a gel-like fluid called the vitreous humor · The vitreous helps maintain the shape of the eye and supports the lens · 99% water, the rest is a mixture of collagen, proteins, salts and sugar

Macular sparing

· Macular sparing is visual field loss that preserves vision in the center of the visual field, otherwise known as the macula. · It appears in people with damage to one hemisphere of their visual cortex and occurs simultaneously with bilateral homonymous hemianopia (half of vision in both eyes same side) or homonymous quadrantanopia (only a quarter same quarter in both eyes). They will still see the centre because the damage excluded the macula). Macular splitting = exactly the opposite no vision in the centre. · Likely due to the wide representation of the macula on the cortex that receives collateral blood supply both from the posterior and middle cerebral arteries.

External Anatomy of the Eye

· Protective and supportive structures · Eyebrows - Prevent sweat and debris from sliding into the eye (also aid communication and protect from extremely bright light) · Eyelids - Folds of skin that cover and protect the human eye. · The levator palpebrae superioris muscle retracts the eyelid. · The human eyelid features a row of eyelashes along the eyelid margin, which offer additional from dust and foreign debris, as well as from perspiration (sweat). · The palpebral commissure (Canthus) is the corner of the eye where the upper and lower eyelids meet. · The lateral palpebral commissure (commissura palpebrarum lateralis; external canthus) is more acute than the medial, and the eyelids here lie in close contact with the bulb of the eye. · The medial palpebral commissure (commissura palpebrarum medialis; internal canthus) is prolonged for a short distance toward the nose, and the two eyelids are separated by a triangular space, the lacus lacrimalis

Myopia

· Short sightedness · Eyeball too long · Distant objects focussed in front of the retina and blurred · Near objects are focussed on the retina and clear · Corrected with a 'minus' or concave spherical lens

Synthesis of Neurotransmitters

· Small molecular weight neurotransmitters (NT) are synthesised in nerve terminals · Peptide NTs are synthesised in neuronal cell bodies and transported down the axon to the nerve terminals · NT synthesis is tightly regulated · This is achieved by regulation of the "rate controlling enzyme" (invariably the first enzyme in the synthetic pathway)

Structures of the Eye and their function: Sclera

· The "white" of the eye. · Tough, opaque tissue that extends around the eye · Surrounds the eye and gives the eye its shape · Protection from injury · Provides attachment to the extraocular muscles

Lacrimal Apparatus of the Eye

· The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage. It consists of: · The lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the human eye. · The lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, by which the fluid is conveyed into the cavity of the nose, emptying anterioinferiorly to the inferior nasal conchae from the nasolacrimal duct. · The innervation of the lacrimal apparatus involves both the sympathetic supply through the carotid plexus of nerves around the internal carotid artery, and parasympathetically from the lacrimal nucleus of the facial nerve.

The Macula & Fovea

· The macula is an oval yellowish area surrounding the fovea (rich in cone cells -> area of highest visual acuity) near the centre of the retina in the eye · Responsible for giving sharp, coloured central vision · Used for reading, recognizing faces and watching TV · Any disease that affects the macula will cause a change & impairment in central vision · Retinal vessels don't reach this area directly - to not effect visual acuity

Structures of the Eye and their function: Pupil & Iris

· The pupil is a hole located in the centre of the iris of the eye that allows light to enter. · The iris is the coloured part of eye · It is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina · This is achieved through the sphincter pupillae and dilator pupillae muscles (radially decrease or increase the diameter of the iris)

Structures of the Eye and their function: The conjuctiva

· Thin, clear layer · The conjunctiva is a tissue that lines the inside of the eyelids and covers the sclera · Highly vascularized (branches of ophthalmicand ex. carotidarteries) · Lubricates the eye (produces mucus and some tears) and contributes to immune surveillance by preventing microbes from entering the eye.

Structures of the Eye and their function: Cornea

· Transparent layer at the front & centre of eye · Located in front of the iris · Avascular · The cornea (with the anterior chamber and lens) refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. · However, its focus is fixed, thus does not aid with accommodation.

Rods

· about 120 million of them in each eye. · highly sensitive to light and even a single photon can cause them to activate, making them great for seeing in low light conditions. Multiple rods excite a ganglion at a time create blurry perception · only offer black and white vision.

Cones

· about 6 million cones in each eye · most of them are located in the macula which is an oval spot in the middle of the posterior retina. At the center of the macula is the fovea which contains the highest concentration of cones and is the part of the retina that offers the highest visual acuity. Each con connect to its own ganglion cell creating a sharp image. · less sensitive than rods to light, and each cone can detect either a red, green, or blue wavelength of light.

Dural infoldings divide the cranial cavity in compartments

• Falx cerebri (cerebral falx - sickle-shaped) • divides right and lefthemisphere • Tentorium cerebelli (cerebellar tentorium) • Divides supratentorial and infratentorial compartments • Tentorial notch - brainstem extends from the posterior into the middle cranial fossa • Falx cerebelli (cerebellar falx) • Partially separates the cerebellarhemispheres • Diaphragma sellae (sellar diaphragm) • Partial roof over the hypophyseal fossa. Covers the pituitary gland and has the aperture for passage of infundibulum and hypophyseal veins

Neurological Field Defects

• Radiation/Cortex Lesion - Hemonymous Loss - CVA -congruous - Tumours -incongruous • Optic Nerve Lesion - Central Scotoma • Chiasmal Lesion - Bitemporal Loss - Pituitary Tumours

Examination in adult with hearing loss and/or tinnitus

❖Otoscopy - looking at TM ❖Tuning fork tests ❖Cranial nerves ❖Examination of the Post-nasal-space ❖Audiometry