Week 130 - Ophthalmology General Flashcards
What is emmetropia?
Normal refractive state of the eye (aka normal vision)
What lens do you use to correct hypermetropic vision?
(long-sighted) - Convex lens
What lens do you use to correct myopic vision?
Concave lens
What receptors are situated on the circular muscle of iris?
M3 receptors (parasympathetic) -> constricting pupil
What receptors are situated on the radial muscle of iris?
β1 receptors (sympathetic)
-> dilating pupil
At what receptor does Atropine act and what are its effects (with regards to the eye).
M3 (antagonist) - Pupil dilation
At what receptor does Homatropine act and what are its effects (with regards to the eye).
M3 (antagonist) - Pupil dilation
At what receptor does Cyclopentolate act and what are its effects (with regards to the eye).
M3 (antagonist) - Pupil dilation
At what receptor does Tropicamide act and what are its effects (with regards to the eye).
M3 (antagonist) - Pupil dilation
At what receptor does Phenylephrine act and what are its effects (with regards to the eye).
α1 (agonist) - Pupil dilation
The anterior retina is supplied by which artery?
Central Retinal artery
What is supplied by the posterior ciliary arteries?
Optic nerve head, fovea/macula, posterior retina and the photoreceptors
Also Choroid
What visual acuity is considered as “legally blind”?
6/60
What is scintillating scotomata?
“water running down window, kaleidoscope pattern” (symptom of migraine (the aura), emboli and giant cell arteritis)
A 63-year old male attended his optometrist complaining of “spots before the eyes”. Suggest two causes of these symptoms.
1) Posterior vitreous detachment
2) Vitreous haemorrhage
3) Posterior segment inflammation (uveitis)
A 30 year old male presents with blurred vision in R eye, dull ache + red (acute). He takes mesalazine for UC. Likely diagnosis?
Uveitis
Name THREE glands in the eyelid
Sebaceous glands (glands of Zeis) Ciliary glands (glands of Moll) - modified sweat glands Tarsal glands - pour oily secretion onto the margin of lid
Name TWO muscles of the eyelids
Orbicularis oculi - closes eyelids
Levator palpebrae superioris - raises the upper lid
What passes through the nasolacrimal canal?
Nasolacrimal duct - carries tears from lacrimal sac into the nasal cavity
What passes through the Inferior Orbital fissure?
Zygomatic Branch of Maxillary Nerve
Inferior ophthalmic vein
Sympathetic Nerves
What passes through the Superior Orbital fissure?
Lacrimal Nerve, Frontal Nerve
Trochlear Nerve, Oculomotor Nerve, Abducent Nerve
Nasociliary Nerve, Superior Ophthalmic Vein
Where is Aqueous Humour found and where is it secreted from?
Anterior + Posterior Chambers
Secretion from ciliary processes
It then ends up flowing into the canal of Schlemm
Nourishes cornea + lens
Where is Vitreous Humour found and where is it secreted from?
Transparent gel filling eyeball
Not actively replaced
What is an EFFERENT PUPILLARY DEFECT, and what is signifies?
One eye remains dilated regardless of which eye light is shone into. Lesion in efferent limb (e.g. third nerve palsy)
What is a Relative AFFERENT PUPILLARY DEFECT, and what it signifies?
Both eyes dilate when light is swung across from normal eye, and shone into affected eye. Lesion anterior to chiasm
Which muscles insert into the Annulus of Zinn?
Lateral Rectus, Medial Rectus, Superior Rectus, Inferior Rectus, Superior Oblique
What is the innervation of the muscles of the orbit?
LR6 SO4 3
Where does the occulomotor nerve originate (names of nuclei)?
Somatic Motor Nucleus (voluntary)
Edinger Westphal Nucleus (accomodation + constriction)
Which nerve is most commonly injured when Intra-cranial pressure rises?
Abducent Nerve - causes medial deviation of eye + diplopia
What are the functions of Ciliary Ganglion?
Sensation of part of eye
Pupilary dilation + elevation of upper eyelid (sympathetic)
Pupillary constriction and accomodation (parasympathetic)
What are the symptoms (3) of Horner’s Syndrome?
Ptosis, Miosis (constriction of pupils), Anhidrosis (lack of sweat)
What are the causes of Horner’s Syndrome?
1) Pancoast tumour of lung
2) Thoracic aortic aneurysm
3) Trauma
4) Compression along sympathetic chain
What would the position of eye be in occulomotor nerve palsy?
Dilated pupil + eye down and out
What is hypertensive retinopathy?
damage to retina due to HIGH BP
What is Optic Neuritis?
Inflammation of optic nerve (may cause complete or partial loss of vision)
What is Strabismus?
Eyes not properly aligned with each other
What is Nystagmus?
Eye moving in a “jerky” fashion
What are the two types of Glaucoma?
Open Angle - canal of Schlemm blocked
Closed Angle - iris obstructs trabecular network and subsequently the canal of Schlemm
What are the secondary causes of Glaucoma?
Inflammation/uveitis
Trauma
Drugs (e.g. steroids)
Diabetes/neovascular
What is the most common malignant intraocular tumour of children?
Retinoblastoma (Flexner-Wintersteiner rosettes on inspection)
What is a cataract?
Opacification of the lens due to denaturation of proteins in lens fibres - loss of visual acuity and contrast
What is Giant Cell Arteritis?
Inflammation of large + medium sized arteries (usually of head and neck). Leads to blurred vision or sudden blindness, headaches, tender temporal artery. Emergency - high dose steroids
Name (3) the branches of V1
1) Frontal Nerve (i)Supraorbital nerve (ii) Supratrochlear nerve
2) Lacrimal Nerve
3) Nasociliary Nerve
What is Anisocoria? and name two types
Difference in pupil sizes
1) Adie pupil - parasymp defect = large atonic pupil
2) Horner’s syndrome - symp defect = small pupil
What is sympathetic ophthalmitis?
v. rare complication of eye trauma. antigens exposed -> autoimmune reaction = can go blind
What is a hyphaema?
Bleeding between iris and cornea (i.e. anterior chamber)
What are the two types of macular degeneration?
Acute (“wet”) macular degeneration - neovascular
Non-neovascular (“dry”) - little impact on vision
What is the treatment for neovascular (“wet”) macular degeneration?
Anti-VEGF (Ranibizumab (Lucentis))
What is Charles Bonnet Syndrome?
Visual hallucinations in people with macular degeneration
What is the process that occurs in Rods/Cones in the DARK?
GTP is converted to cGMP (by guanylate cyclase).
cGMP keeps Na+/Ca2+ channels open -> cell depolarised
What is the process that occurs in Rods/Cones in the LIGHT?
Photon hits Rhodopsin (11-cis retinal -> all-trans retinal)
Opsin is activated -> activates phosphodiesterase
cGMP->GMP = Ca/Na channel closes
Na/Ca exchanger removes Ca -> membrane Hyperpolarised (less glutamate released)
How does the photoreceptor:bipolar cell ratio vary?
Periphery - many photoreceptors:bipolar cell
Centre - single photoreceptor:bipolar cell
What is used to assess colour vision defects?
Ishihara pseudoisochromatic plates
Name three photosensitive cells?
Rods
Cones (three types - colour)
Photosensitive retinal ganglion cell (regulation of diurnal rhythms)
What clinical feature will be present in retrobulbar neuritis (common in MS)?
Relative afferent pupillary defect
What are the differential diagnoses in a patient with light-near dissociation?
Dorsal midbrain syndrome -causes include pineal tumour, MS, brainstem infarction. (neurosyphilis)
What are the divisions of the Lateral Geniculate Nucleus?
6 laminae
1,2 = magnocellular (movement, temporal contrast)
3-6 = parvocellular (colour, spatial contrast)
1-6 = Koniocellular (blue-yellow contrast)
What does conjunctiva line?
Eyelid + anterior eyeball
What keeps the cornea transparent?
Ion pump in the endothelium keeps the collagen fibrils within the stroma in a state of dehydration
What happens in accommodation?
Pupil constriction (circular muscle (sphincter pupillae) contraction)
Lens becomes more convex (contraction of muscles of ciliary body)
Controlled by parasympathetic fibers (CN III) from the Edinger-Westphal nucleus
What does vitreous humour consist of?
99% water
Collagen fibrils & hyaluronan
What else can shingles on the end of the nose affect?
Nasociliary nerve - branch to eyeball also supplies tip/side of nose
VZV infection can affect both
What kind of vision defect would a pituitary tumour cause?
Bitemporal hemianopia
What are the main causes of conjunctivitis?
Bacterial (e.g. chlamydia), Viral (Adenoviruses, HSV)
What are the main features of glaucoma?
Optic disc cupping
↑intraocular pressure
?Visual field loss
What is the most common type of glaucoma?
Acquired Primary Open Angle Glaucoma (POAG)
What are the treatments for glaucoma?
1) topical β-blockers (e.g. timolol)
2) carbonic anhydrase inhibitors (e.g. dorzolamide)
3) α-adrenergic agonist (e.g. apraclonidine)
4) parasympathomimetic (pilocarpine)
What are the main causes of Retinal Detachment?
Tractional - retina is pulled
Exudative - caused by breakdown of the blood-retinal barrier, allowing fluid to accumulate in subretinal space
Rhegmatogenous - caused by tear or hole
