basics Flashcards
Breakdown of retina?
9 layers + RPE (deep)
Choroidal layer provides blood supply and nutrition to retina.
Outermost layer is inner limiting membrane,
2nd superficial is RNFL
what is optic disc?
Optic nerve head. Beginning of optic nerve, point of exit for ganglion cells
Where is optic disc relative to macula?
Optic disc nasal to macula.
What is myopia?
Axial length of eyeball is long. Incoming light rays focused in front of retina
What is astigmatism?
Inequality in 1 or refractive surface of eye, preventing light rays from focusing clearly at 1 point on retina
What is presbyopia?
Part of normal ageing. Eye loses accommodative ability to focus on near objects due to loss of lens elasticity and subsequently convexity
How does proliferative diabetic retinopathy cause visual loss?
- Diabetic maculopathy
- Vitreous haemorrhage
- Tractional retinal detachment
What is a cataract?
Opacity or discolouration of crystalline lens.
Types of cataracts?
Cortical cataract
Posterior subcapsular cataract
Mixed cortical & nuclear cataract
White mature cataract
What is glaucoma?
It is an optic neuropathy with imbalance btw prod and drainage of aqueous humour
Causes of acute angle closure glaucoma?
- Peripheral iris suddenly and completely blocksfiltration angle, sudden forward shift of lens-iris diaphragm
causing pupillary block -> impaired drainage -> sudden ↑ in IOP - Shallow anterior chamber: genetic
- Thicker lens: with ↑ age
Clinical presentation of Horner’s?
Partial ptosis of upper eyelid
Inverse ptosis of lower eyelid
Relative enophthalmos due to ptosis of upper and lower eyelids
Miosis
Anisocoria worse in dark
Ipsilateral anhidrosis
Harlequin sign
Heterochromia iridis
Symptoms of glaucoma?
Sudden unilateral painful red eye + vision loss.
Ipsilateral headache
N/V
Coloured halos, rainbows around lights
Photophobia
Signs of glaucoma?
Red eye with circumciliary injection
Fixed mid/semi dilated non-reactive pupil
Hazy cornea from corneal edema
Shallow anterior chamber
High IOP
Mx of acute angle closure glaucoma?
Ocular massage
Pilocarpine eyedrops to miose pupil and reverse pupillary block
IV acetazolamaide to lower IOP
Symptoms of vitreous haemorrhage?
Sudden painless BOV
a/w floaters
Signs of vitreous haemorrhage?
Poor red reflex
Confirm with dilated fundal exam
RF for Rhegmatogenous RD?
Acute posterior vitreous detachment
Age
High myopia
Ocular Surgery
Trauma
Aphakia
Retinal degeneration
Causes of CRVO?
Extrinsic pressure on vein due to raised IOP
Intrinsic vessel wall issues e.g. DM, HTN, HLD, SLE
BIGGEST usu due to hyperviscosity issues
Classify hyperviscosity acc to which cell line affected
Fundoscopy of RAO?
Pale retina
Cherry red spot at macula
Attenuated arterioles
Cotton wool spots
Wet AMD?
Occurs rapidly, causing severe central vision loss
Choroidal neovascularization
Fluorescein angiography to check neovascularization
Early detection with Amsler Grid Eye test
Clinical presentation of Wet AMD?
Painless metamorphopsia
Central scotoma
Peripheral vision intact
Others include BOV, low colour vision
What is Retinitis Pigmentosa?
AR-inherited degeneration of retina
Loss of retinal photoreceptors, more rod > cones lost.
Retinal atrophy
Clinical presentation of Retinitis Pigmentosa?
Night blindess
Poor central + peripheral vision
Glares
Fundoscopy of Retinitis pigmentosa?
Areas of bone-spicule pigment clumping in mid-periphery of retina
Thinning of retinal arterioles
Pale optic disc due to thinning out of vessels
Classification of optic neuritis?
Papillitis = inflamm of optic disc. Blurred disc margins
Retrobulbar = no visible disc swelling
Neuroretinitis = swelling of optic disc + peripapillary retina/macula
Causes of optic neuritis?
Idiopathic
Demyelinating e.g. MS
Post-infectious
Infections
Autoimmune
Presentation of optic neuritis?
Pain with ocular movement
RAPD
Poor vision (variable)
VF defect e.g. central scotoma
Invx for Optic neuritis?
MRI brain TRO MS
TRO intraocular inflamm
2 complications of cataracts?
Glaucoma
Repeated anterior uveitis
Optic maculopathy causes what VF defect?
Near-central scotoma
Triad of glaucoma ocular signs?
Raised IOP
Disc cupping
VF defect
What are cotton wool spots
Microinfarct of NFL. Infarct causes swelling
How do hard exudates form?
CRL from vessels that leak from microaneurysms. Suspect diabetes-related
What are drusens?
Faeces of RPE. So theyre inside or below RPE.
Wriggly spots are what
Tortuous vessels due to NVE or NVD. They are very fragile, and can burst on exertion like coughing or vomiting.
Cause of silver wiring?
arteriolosclerosis
Cause of BRVO?
HTN causes venous Pa to be high. So its a complication of hypertensive retinopathy.
Cause of CRVO?
Hyperviscosity issues.
Classify into what cell line is the problem. E.g. platelets = thrombocytosis, WBC = leukemia, RBC = vWF disease etc.
What is peripapillary atrophy?
Atrophy in layers of retina and RPE around optic nerve at the back of the eye.
If i see hard exudates then what do i look out for?
Aneurysms! Be it Macro or micro
How does blood affect vision?
It causes fibrosis of retina, which causes tractional retinal detachment = leading to tears.
The fibrosis can further open up the fovea as well. Vision will cfm drop.
Commonest nerve affected in brain trauma or concussion?
4th nerve. Its intracranial course is the longest.
What movements are hit in intraocular ophthalmoplegia?
Impaired adduction of ipsilateral eye with nystagmus of abducting eye.
IPAD CLABNYS
What is weber’s syndrome?
Midbrain stroke causing ipsilateral CN3 palsy + contralateral hemiplegia.
Diplopia + Ptosis + afferent pupillary defect.
Sometimes ataxia + parkinsonian rigidity come tgt
Higher mental function usu normal
What is benedikt syndrome?
Neurological condition secondary to specific damage in midbrain causing:
1. Ipsilateral oculomotor palsy
2. Contralateral hemiparesis
3. Contralateral cerebellar ataxia and/or Holmes tremor and/or choreoathetosis
Uhthoff phenomenon in MS?
In high body temp, optic nerve demyelinates. Nerve conduction is slow. There is blurring of vision
Do MRI to check for demyelination plaques
What lesion in One and a half syndrome?
MLF lesion + Ipsilateral PPRF lesion. PPRF is horizontal gaze centre.
How to tell thru VF if chiasmal lesion is above or below chiasm?
Bottom VF affected more in supra-chiasmal lesion.
Infra-chiasmal = suspect pituitary tumour
Supra-chiasmal = suspect craniopharyngioma.
Altitudinal VF defect is due to?
Stroke of optic nerve. Anterior ischemic optic neuropathy causes pale swollen optic disc.
Can have RAPD
Causes of ischemic optic neuropathy?
aka stroke of optic nerve
Arteritic = GCA
Non-arteritic = no vascular RFs
ischemic optic neuropathy causes stroke of optic nerve
The more retro-chiasmal the lesion the more _____ the vision loss
The more retrochiasmal the lesion the more congruent the vision loss
What does it mean if optic nerve is straight and looks stretched?
It means proptosis cuz usu optic nerve is stretched out. Anyone with proptosis must do CT!!
Presentation of GCA?
pain on chewing, polymyalgia rheumatica
How to classify Horner’s ?
Pre ganglionic vs Post-ganglionic vs Central
Pre-ganglionic is Pancoast tumour.
Post is ICA aneurysm.
central is made of hypothalamus, brainstem, cervico-thoracic spinal cord
Vasodilation and anhidrosis only in pre-ganglionic. There is flushing of face on affected side.
Differentials for multiple cotton wool spots?
- Diabetic retinopathy + HTN retinopathy. These 2 are always sets!
- Radiation retinopathy
- HIV retinopathy (gays)
Tx for AMD?
Anti-VEGF.
Laser treatment has been phased out.
Vitamin Formulations for AMD are all useless except for 1
What does pale retina on fundoscope mean?
Retinal edema / swelling. Due to clots!
The swelling is only in acute phase. After a while it returns to normal colour.
OCT scans show retina very thin because the cellular layers have died.
How do cherry-red spots in CRVO form?
The area doesnt swell as much cuz the actual fovea doesnt have the layer of nerves that other parts have, so the deeper red choroidal colour still passes through.
Causes of CRAO?
Vessel wall occlusion = atheroma, arteritis
Embolization = Carotid atheromatous plaque, heart valve lesions e.g. bacterial endocarditis, cardiac wall issues e.g. atrial myxoma
types of emboli = CRL, fibrinoplatelet, calcific
Complications of CRVO?
Macular edema
Haemorrhage
Neovascularization due to ischemia, in: retina, optic disc, angle. The new vessels in angle raises risk of glaucoma
Vascular comp = microaneurysms, optociliary vessels
Tx for CRVO?
Anti-VEGF
PRP to reduce neovascularization
Diff btw optic disc and macula issues?
Optic disc is actl blind spot. Extent of vision affected is decided by how MACULA is affected, not the optic disc. Even if CD ratio is very high, only way to affect optic disc is through high IOP -> compressive optic neuropathy. Optic disc affected on fundo doesnt mean vision is alw hit.
How does IRMA grow on retina?
Flat on retina. It is a hallmark of non-proliferative diabetic retinopathy.
It doesnt grow into cavity. IRMA usu doesnt leak, so angiogram wont show IRMA.
What surgery for retinal detachment?
Pneumatic retinopexy. Seal the tear
Where and dot and blot haemorrhages?
Intraretinal blood in deeper layers, round in shape.
In what order are muscles affected in thyroid eye disease?
IMSL rectus!! This is due to extraocular muscle infiltration and fibrosis causing restricted extraocular movements -> binocular diplopia
What does flame haemorrhage mean?
Intraretinal blood in superficial NFL
What is scleromalacia perforans?
Anterior necrotizing scleritis without inflammation. It causes autoimmune-mediated widespread damage to episcleral and scleral vessels.
Usu in women with long-standing RA
Is hypertensive retinopathy usu symptomatic?
Usu no symptoms
What does focal closure of retinal vasculature point to?
Microinfarcts
What does silver wiring point to?
When central light reflex occupies entire width of arteriole.
When does AV nipping occur?
In chronic HTN, arteriolar walls get thicker and sclerose, and while crossing over the venules they compress and constrict them. Retinal veins are usu more pliable.
What does eclipse sign mean in fundoscopy?
It means shallow anterior chamber. There is higher risk of angle closure glaucoma.
What are hypopyons?
Deposits of RBC in lower part of anterior chamber.
Complications of cataract surgeries?
Posterior capsular rupture
Endophthalmitis
How to divide ischemic optic neuropathy?
Arteritic vs Non-arteritic.
Non-arteritic commonly has painless LOV on awakening due to nocturnal hypotension.
Arteritic has bilateral rapidly progressive severe vision loss.
Arteritic e.g. GCA. They often come with associated symptoms
In what direction are vertical recti muscles attached?
Temporally. Action as elevators and depression are best seen in abduction
in what direction are oblique muscles attached?
Nasally! Actions as depressors and elevators are best seen in adduction.
How to diff btw orbital cellulitis and other stuff of red eye?
z
Extraocular movements can be hit in extra-ocular movements.
What to check for in orbital cellulitis?
Got RAPD?
Got chemosis?
Visual acuity
IOP
Presentation of blowout frac in eye?
Inferior Rectus is trapped so eye cannot go up.
Eye balls sinks in cuz the floor is gone = enophthalmos
Diplopia sometimes
What is canaliculus?
lacrimal passageways in upper and lower eyelid where tears pass through into lacrimal sac.
How to know if got globe injury in trauma?
Red injected eye
Possible iris prolapse
vision issues
IOP raised
How to check for punctal stenosis in elderly?
In elderly -> Punctal stenosis -> Nasolacrimal duct obstruction -> Do syringing to check
Features suggestive of malignancy in eye?
Growing in size
Irregular margins
Rolled edges
Loss of lashes and lid
E.g. sebaceous gland CA. Differential for chalazion.
Symptoms of ectropion?
Ectropion is evertion of eyelid. 덧눈꺼풀
Constant tearing (main)
Dry eyes
What is dermatochalasis?
Eyelid skin drooping due to ageing
What does gonioscopy check for?
IOP
Done when u feel angle is too narrow. Check if angle structures are still open.
What is hyphema?
Blood collection in ant chamber. Mostly due to blunt trauma. Post hyphema u must do gonio. Can have glaucoma later on.
What operation for angle closure?
Peripheral iridotomy. Creates space in the iris.
Iridoplasty also sometimes done
What is glaucomflecken sign?
small anterior subcapsular grey-white fleck-like opacities secondary to lens epithelial cells necrosis.
Lens looks a bit opaque in centre post-glaucoma. Catarct will form
What are drance haemorrhages? Where are they found?
Disc hemorrhages that lie within the peripapillary retinal nerve fiber layer. Always found near the disc.
how to diff btw ocular HTN and normotension glaucoma?
Pa high normal disc normal VF -> ocular HTN
Pa normal, disc and VF got issues -> normotension glaucoma.
Examples of drugs that cause optic neuropathy?
Ethambutol
Ethanol!
Amiodarone
Isoniazid
Hydroxychloroquine
Commonest cause of optic neuritis in young ppl?
Demyelinating disease, most often MS
Symptoms of optic neuritis?
Colour vision is hit.
Central or centrosectoral scotoma is seen in ON.
Optic neuritis needs imaging!!
Ischemic optic neuropathy doesnt cause colour vision loss.
Give IV pred in ON
Differentials for unilateral disc swelling?
Optic neuropathy
- Compressive
- Ischemic
- Inflamm
- Infiltrative
Others = Uveitis, CRVO
Common cause of CN6 issue in SG?
NPC.
R upper movement is affected
Which muscles are innervated by CN3?
levator palpebrae, all EO muscles
except SO + LR + Sphincter papillae
Facts about pupil issues?
Often asymptomatic, picked up on routine exam or screening.
Sec to afferent or efferent defects
Urgent neuroimaging needed if got alot of pain.
Cause of convergence insufficiency?
Optic neuropathy in nerves controlling extraocular muscles
What can cause uniform angiogenesis across the sclera?
Contact lens overuse
What can cause hazy cornea
Very dry eyes
Causes of small irregular pupil with light near dissociation?
Argyll robertson pupil
Uveitis due to syphilis. Iris becomes sticky, sticks to anterior capsule, then cannot dilate.
What can cause colour halos?
severe raised IOP e..g acute angle closure glaucoma. This is due to diffraction of light by edematous cornea.
How does peripapillary atrophy look like?
Many black dots around optic disc.
Common in myopic eyes.
What can neovascular glaucoma + high IOP cause?
Corneal decomposition. Until there is no more pupil and eventually pt goes blind.
Causes of anisocoria worse in light?
Cannot constrict, parasympathetic pathway error
CN3 palsy (constricts with 1% pilocarpine drops)
Adie’s tonic pupil (constricts with 0.1% pilocarpine drops)
Pharmacologic (no constriction with 1% pilocarpine)
Trauma/mechanical = rupture of pupillary sphincter
What is physiologic anisocoria?
20% physiologic.
Pupillary function is normal
Degree of anisocoria remains same in light and dark
Anisocoria rarely less than 1mm
Head posture in examination of diplopia?
Head turn = towards side of abduction weakness e.g. CN6 palsy, Duane’s
Head tilt = away from side of CN4 palsy
Chin down = in bilat CN4 palsy
Chin up = in bilateral ptosis.
Causes of CN6 palsy
must exclude raised ICP = false-localizing CN6 paresis. CN6 gets stretched along sharp edge of petrous temporal bone
TRO NPC
Common causes are ischaemic, tumours, trauma
Causes of light near dissociation?
Adie’s tonic pupil commonest
Neurosyphilis
Parinaud syndrome
Adie’s is generally benign
Adie’s seen in DM, Sjogrens, autonomic disorders
What is Bell’s reflex for eye?
Upward and lateral deviation of eyes during eyelid closure against resistance.
Inverse bells could be due to peripheral CN7 palsy, or ptosis repair
What is retinoschisis?
Abnormal splitting of retina’s neurosensory layers usu in the outer plexiform layer
What is a pterygium?
Tissue growth of conjunctiva onto cornea of the eye
Types of strabismus?
Concomitant -> die to uncorrected refractive error, unilat visual impairment, amblyopia, cerebral damage
Incomitant -> due to paresis or paralysis of extraocular muscles, e.g. CN palsy, MS, myopathies, trauma, microangiopathic vasculopathy.
Angle of deviation alters depending on direction of gaze
Causes of central Horner’s
Brainstem stroke
Cervical spinal cord injury
Brain tumours
MS
Meningitis
Pontine haemorrhage
how to differentiate hard exudated from retinal scarring?
Scarring = yellow, bright
Exudates = not as bright
Types of retinal detachment?
Rhegmatogenous
Tractional
Exudative
Rhegmatogenous commonest
Type of glaucoma in thyroid eye disease?
Open angle glaucoma
not closed angle
Causes of CN6 palsy
Ischemia - GCA, CVS RFs
Compression of BOS - NPC
Raised ICP
CPA angle tumour
Cavernous sinus syndrome
Infectious - meningitis, mastoiditis, sphenoiditis
Sarcoidosis
Causes of post-ganglionic Horner’s
ICA dissection
Cavernous sinus
Tumour
Herpes Zoster infeciton
Causes of Pre-ganglionic Horner’s?
Pancoast tumour
Common carotid dissection
Iatrogenic
