Week 8 - Ophthalmology B

anencephaly

congenital deformity in which some or all of fetal brain is missing

supression

sensory adaptation to misaligned eyes where the visual cortex learns to ignore the double image by suppressing the visual input from the deviated eye, in the long term this can lead to amblyopia

orbital rim

anterior rim of orbit

neuroblasts

brain progenitor cells that asymmetrically divide into other neuroblasts or nerve cells

pontine fissure

called secondary flexure occur later end of 4th week beginning of 5th located at dorsal side and starts to form 4th ventricle

laser therapy

can be used to treat glaucoma, eg selective laser trabeculoplasty (improves aqueous drainage) or cyclodiode laser therapy (reduces aqueous production)

cortical cataract

cataract that forms in the lens cortex, star-shaped opacity (spokes), commonly caused by diabetes & ageing

nuclear catarct

cataract which happens when fibers near the central portion of the lens (nucleus) thicken with age, appears yellow-brown in colour

secondary cataract

cataracts can form after surgery for other eye problems, such as glaucoma, opacification of posterior capsule, requires YAG laser to remove residue

neural crest cells

cells at the tip of the neural fold; this group of cells gives rise to many components of the peripheral nervous system

telencephalon

cerebral hemispheres embryologically

microglial

come from mesenchymal cells surrounding the developing spinal cord (but originate in bone marrow & yolk sac), scattered throughout grey & white matter in spinal cord & brain

CN4 palsy

extorsion, compensatory head tilt towards opposite shoulder, hypertropia, imapired depression in abduction (because SO is paralysed), difficulty reading or walking down stairs due to diplopia, causes: trauma, congenital, microvascular, SOL

yoke muscles

extraocular muscle pairs that act together to produce conjugate eye movements

Goldmann applanation tonometry

eye is numbed and measurements are taken directly on the eye, machine presses down on cornea to assess how much resistance there is to calculate the IOP, gold standard for diagnosing acute closed angle glaucoma

meroencephaly

failure of rostral neuropore to close, absence of large part of brain and skull, either miscarriage or do not live longer than a few days

orbital septum

fibrous membrane forming the anterior border of the eye, extending from orbital margins to the tarsi and palpebral ligaments

fluorescein stain

fluorescent dye applied to the eyeball to view corneal abrasions or ulcers

paraxial mesoderm

forms somites

proptosis

forward protrusion of the eye, most commonly caused by thyroid eye disease (also primary orbital tumours, mets), can measure with exophthalmometer

retinal pigmentosa

genetic disease causing the degeneration of the retina and death of photoreceptors, resulting in gradual loss of vision

lacrimal gland

gland located in the upper outer region above the eyeball that secretes tears

endophthalmitis

inflammation of the inside of the eye, a rare but serious complication of surgery, usually caused by staph aureus

dacrocystitis

inflammation of the lacrimal (tear) sac, DDx of lacrimal sac mass/tumour, PO Abx, darinage, consider dacro-cysto-rhinostomy

dacroadenitis

inflammation of the lacrimal gland, recent onset swelling & upper lid discomfort, S shaped lid contour, lacrimal gland swollen, dacroadenitis, settles on conservative Tx

anti-vegf therapy

intravitreal injections given every ~6 weeks to improve/stabilise vision, makes blood vessels recede & blood resorbs back into eye

esotropia

inward deviation of eyes (cross-eyed)

esophoria

inward drifting of the eye

lacrimal sac mass

suspect this if a patient has blood stained tears

lowe syndrome

syndrome characterized by vision problems including clouding of the lenses of the eyes (cataracts) that are present at birth, kidney problems that usually develop in the first year of life, and brain abnormalities that are associated with intellectual disabilities.

conus medullaris

tapered end of spinal cord at birth is L3 in adults is L1-L2

canthal tendons

tendons located medially & laterally, connect tarsal plates to orbital rim

comitant strabismus

that due to faulty insertion of the eye muscles, no limitation of movement, ca be esotropias or exotropias

Neuroplasticity

the ability within the brain to constantly change both the structure and function of many cells in response to experience or trauma

Polypoidal choroidal vasculopathy

thought to be a variant of wet AMD, characterised by polypoidal dilatation of choroidal vasculature with serosanguineous PEDs

metamorphopsia

visual distortion of objects

Sherington's law of reciprocal innervation

when a muscle agonist contracts to move an eye in a particular direction, its ipsilateral antagonist muscle relaxes to an equal extent

graves eye disease

45% of graves patients have mild symptoms (eye discomfort, oedema, erythema, conjunctival redness), 3-5% severe (sight threatening)

notochord

A rod of tough, flexible material that runs the length of a creature's body, providing the majority of its support

bruch's membrane

Innermost layer of the choroid, separates choroid from retina

hering's law

Law of equal innervation; states that yoked muscles are equally innervated, i.e. when a nervous impulse is sent to a muscle causing it to contract, an equal impulse goes to its contralateral synergist to maintain parallelism of the visual axis

cervical flexure

between rhombencephalon (hindbrain) and spinal cord

incomitant strabismus

The amount of misalignment depends upon which direction the eyes are pointed due to weakness of an ocular muscle or muscles, there is limitation of eye movement, can be paralytic or restrictive

CN3 palsy

Think PCOM aneurysm! ptosis (due to LPS paralysis) down & out (unopposed actions of LR & SO) dilated pupil, no response to accomodation reflex (but consensual reflex is still present)

alternating cover test

Used to differentiate if the misalignment is a tropia or phoria, · Similar process as cover test but you occlude each eye for 1-2s then quickly remove the occluder to restore binocular vision (& repeat)

paramedian pontine reticular formation (pprf)

a brain region without clearly defined borders in the center of the pons. It is involved in the coordination of eye movements, particularly horizontal gaze and saccades.

congenital cataract

a clouding of the lens that is present at birth. (1/3rd autosomal dominant, rest due to birth trauma, infection in pregnancy), screened by looking for red reflex, This clouding of the usually clear lens results in hazy vision.

charles bonnet syndrome

a condition in which individuals with eye disease form vivid and detailed visual hallucinations that are mistaken for visual perception

heterotropia

a condition of eye misalignment caused by intraocular muscle imbalance

spina bifida

a congenital defect that occurs during early pregnancy when the spinal canal fails to close completely around the spinal cord to protect it, failure of fusion of one or more neural arches

orbital cellulitis

a diffuse infection of tissues in the orbit, causing grossly swollen eyelids and red eye, sometimes without proptosis, requires admission & IV Abx

wilson's disease

a genetic disorder of copper metabolism that creates a copper toxicity and results in neurologic symptoms such as tremors, impaired speech, inappropriate behaviors, and personality changes, increased risk of developing cataract

neural tube

a groove formed in the top layer of differentiated cells in the embryo that eventually becomes the brain and spinal cord

orbicularis oculi

a muscle in the face that closes the eyelids

punctal occlusion

a painless procedure in which the puncta are blocked, which can cause epiphora

optokinetic reflex

a physiologic phenomenon produced by asking the patient to visually track a succession of moving stimuli, can be considered a combination of pursuit & saccades movements

rostral interstitial nucleus (of medial longitudinal fasciculus)

a portion of the medial longitudinal fasciculus which controls vertical gaze

fundus fluorescein angiography

a procedure used to examine the tiny blood vessels in the eye, fluorescent dye injected into blood stream, must do if suspected wet AMD

usher syndrome

a rare genetic disorder primarily characterized by sensorineual hearing loss accompanied by retinitis pigmentosa

vestibuloocular reflex

a reflex acting to stabilize gaze during head movement, with eye movement due to activation of the vestibular system

peripheral ulcerative keratitis

a serious eye disorder that involves inflammation and ulceration of the cornea (the clear layer in front of the iris and pupil) that often occurs in people who have connective tissue disorders such as rheumatoid arthritis

optic disc (optic nerve head)

a small, circular region where the retinal nerve fibers exit the eye as the optic nerve and where blood vessels enter and exit the eye

superior colliculus

a structure in the midbrain that is part of the brain circuit for the transformation of sensory input into movement output. Its major function is orienting the animal, particularly with eye movements, to objects of interest in the outside world.

second sight phenomenon

a temporary change in vision during early cataract development. Before vision deteriorates, vision, especially close-up reading vision, improves significantly.

cover test

a test that detects a small degree of deviated alignment by interrupting the fusion reflex that normally keeps the two eyes parallel. ask the person to stare straight ahead at your nose, place a card in front of one eye and note the uncovered eye. A normal response is a steady fixed gaze.. if the uncovered eye jumps to reestablish fixation, eye muscle weakness exists

tarsal plate

a thick fold of connective tissue that gives form and support to the eyelids

vergence

a type of eye movement in which the two eyes move in opposite directions; for example, both eyes turn toward the nose (convergence) or away from the nose (divergence).

posterior blepharitis

blepharitis involving inflammation of the meibomian glands

smooth pursuit

a type of voluntary eye movement in which the eyes move smoothly to follow a moving object, generated by occipital parietal, ipsilateral control (left cortex - left eye), mediated by neurons in the PPRF

scotoma

blind spot in vision

restrictive strabismus

an ocular misalignment caused by an extraocular muscle that is hindered or physically prevented from moving the eye, eg thyroid eye disease, orbital mass or orbital wall fracture

filum terminalis

anchors conus terminalis to base of spinal cord;

lateral rectus

abducts the eye

bassen-kornzweig syndrome

abetalipoproteinaemia, caused by a defect in a gene that tells the body to create lipoproteins, leads to progressive neurological symptoms & retinal pigmentosa of fat absorption & metabolism

strabismus

abnormal deviation of the eye

epiphora

abnormal overflow of tears (outflow problems), few associated symptoms, eyes usually white & quiet, seasonal variation (worse in winter), lid position may be normal

hydrocephalus

accumulation of fluid in the ventricles of the brain

medial rectus

adducts the eye

midbrain

aka mesencephalon, forms the diencephalon & part of the midbrain iself

forebrain

aka prosenecephalon, forms the lateral ventricles, cortex & cerebral hemispheres

hindbrain

aka rhombencephalon, forms the remainder of the brainstem

ventricular zone

also called ependymal layer. A region lining the cerebral ventricles that displays mitosis, providing neurons early in development and glial cells throughout life, initial singular layer zone where pseudostratified columnar neuroepithelium cells are located

sensory deprivation amblyopia

amblyopia caused by cataract, ptosis or retinal problem

Refractive amblyopia

amblyopia which occurs when the refraction of each eye is so different that the child uses the eye that focuses the best, resulting in poor development of the other eye

advanced AMD

any of: geographic atrophy at the fovea neovascular AMD

intermediate AMD

any of: many medium drusen at least one large drusen (>125 microns) geographic atrophy not involving the fovea

early AMD

any of: several small drusen at least one medium drusen (63-124microns) mild pigmentary abnormalities

dermatochalasis

baggy eyelid; overabundance and loss of skin elasticity on the upper eyelid causing a fold of skin to hang down over the edge of the eyelid when the eyes are open

drusen

benign deposits on the ocular fundus that show as round yellow dots and occur commonly with aging

choroidal naevi

benign melanocytic lesions of the posterior uvea

posterior subscapular catarct

cataract where the posterior portion of the lens is affected, happens due to migration & enlargement of the lens epithelial cells posteriorly, grainy appearance, caused by ageing, diabetes, steroid use & trauma

watering

excess tear production, may be associated symptoms (eg conjunctival redness), seasonal variation (often better in winter), lid position often normal

extracapsular cataract extraction

excision of most of the lens, followed by insertion of an intraocular lens transplant, used to treat cataracts

refsum disease

deficiency in peroxisomal Phytanyl CoA α-hydroxylase. Phytanate (phytanc acid) buildup. neurological issues, visual ataxia (retinal pigmentosa) , poly neuropathy.

laser iridotomy

definitive management for acute closed angle glaucoma, uses a focused beam of light to create a hole in the iris of the eye

neurulation

development of the nervous system

non-contact tonometry

diagnostic tool used by eye care professionals to measure the intraocular pressure (IOP) inside a patient's eyes, it uses a small puff of air (which is why it's many times referred to as the "puff test") to measure an eye's pressure.

intermediate zone (mantle layer)

differentiated neuroepithelial cells from the ventricular zone, forms the grey matter of the spinal cord

basal (ventral) plate

differentiates into motor (efferent) neurons eg ventral horn

alar (dorsal) plate

differentiates into sensory (afferent) neurons eg dorsal root ganglion

hypotropia

downward deviation of one eye

hypophoria

downward drifting of the eye

prostaglandin analogues

drugs used to treat glaucoma by increasing uveosceral outflow, most potent ocular hypotensives, ocular SEs are common (eg lash growth, iris pigmentation, periocular skin darkening, conjunctival injection)

nuclear sclerosis

drying out of the lens with age

alpha blockers

eg brimodine, apraclonidine can be used to treat glaucoma but avoid concomitant use of antidepressants

carbonic anhydrase inhibitors

eg dorazolamine, brinzolamide Tx glaucoma by reducing production of aqueous, least potent ocular hypotensives but are contraindicated in sulphonamide sensitivity

beta blockers

eg timolol, levoburilol, betaxolol Tx glaucoma by reducing aqueous production, but SEs include asthma/breathlessness, bradycardia, tiredness, depression, erectile dysfunction, hypotension & angina

CN6 palsy

esotropia (unopposed action of MR, SR & IR), reduced abduction (due to paralysis of LR), ipsilateral face turn, patient will often close eyelid of affected eye to stop the diplopia, causes usually benign but unknown

gonioscopy

examination of the angle of the anterior chamber of the eye to determine ocular motility and rotation and diagnose and manage glaucoma

glaukamflecken

grey-white opacities on the anterior lens capsule seen in acute angle closure glaucoma

sulcus limitans

groove of the lateral wall which separates the grey matter into dorsal/alar & ventral/basal plates

neural fold

group of ectodermal cells that slide together to create a fold, which later becomes the neural tube

encephalocele

herniation of intracranial contents (dura, CSF, brain material) resulting from a defect in the cranium, commonly in the occipital region

ocular hypertension

higher than normal intraocular pressure without changes to the optic nerve or visual fields (glaucoma)

neural groove

in the developing embryo, the groove between the neural folds

paretic strabismus

inability of the ocular muscles to move the eye because of muscular paralysis (weak signal or weak muscle) causes: dorsal midbrain problem, INO, CN3/4/6 damage (neuromuscular, MG, myopathies

lagophthalmos

inability to close the eyelids completely

chorioretinitis

inflammation of the choroid and retina, can cause a pigmented lesion in the fundus

optical coherence tomography

laser-based non contact imaging technique used to obtain detailed images of retina, uses infrared light to scan back of the eye

wet AMD

less common form, growth of new, abnormally located blood vessels (choroidal neovascular membrane - CNVM) underneath retina -> sudden loss of vision by leakage of fluid or haemorrhage

pseudostratified columnar epithelium

linings of respiratory passages, cells which initially make up the walls of the neural tube

fabry disease

lysosomal storage disorder; a rare inherited disorder of glycosphingolipid (fat) metabolism resulting from the absent or markedly deficient activity of the lysosomal enzyme, α-galactosidase A (α-Gal A). increased risk of developing cataracts

acute angle closure glaucoma

medical emergency, occurs due to pupil block, painful red eye, blurred vision/haloes, N&V, mid-dilated pupil, cloudy cornea, shallow anterior chamber

midbrain flexure

midbrain region

tropia

misalignment is always there, even when both eyes are open & attempting to work together (identified by the cover test)

phoria

misalignment that only occurs some of the time such as when synchronisation between the eyes is broken by covering one eye (identified by alternate cover test)

dry AMD

most common type of AMD; causes deposits of yellow-colored extracellular material within the macula of the eye, causing possible atrophy of the retina and a gradual loss of central vision

primary open angle glaucoma

most common type of glaucoma in the uk, initially asymptomatic, slowly progressive, frequently associated with raised IOP

Choroidal neovascularization (CNV)

new blood vessels growing into the retina

orthotropic

normal alignment of eyes

exophthalmometer

objective measuring tool to measure protruding eyes. Upper limits of normal are 20 mm in whites and 22 mm in blacks.

cranial neuropore

opening nearest the future head, closes on day 27

normal tension glaucoma

optic nerve damage (glaucoma) despite normal IOP

marginal zone

outer zone of neuroepithelial cells which forms the white matter as axons grow into it from nerve cell bodies

exotropia

outward deviation of eyes

exophoria

outward drifting of the eye

diencephalon

part of the forebrain (proencephalon) which forms the thalamic centres of the brain

myelencephalon

part of the hindbrain (rhombencephalon) which forms the medulla

metencephalon

part of the hindbrain (rhombencephalon) which forms the pons & cerbellum

rhombencephalic isthmus

part of the hindbrain (rhombencephalon) which separates the hindbrain from the midbrain & the cervical flexure demarcates the hindbrain from the spinal cord

acrania

partial or complete absence of the cranium

diabetic keratopathy

patients with diabetes often have corneal epithelial defects that persist or are unresponsive to conventional treatments, corneal endothelial dysfunction, neuropathic cornea

age-related macular degeneration

progressive loss of central vision associated with formation of drusen & changes in the retinal pigmentary epithelium, associated with ageing

orbital fat pads

protects the eye and other structures in the orbit

saccades

quick eye movements from one fixation point to another, initiated in the frontal lobes under contralateral control

red reflex

red glow that appears to fill the person's pupil when first visualized through the ophthalmoscope, absence is suggestive of cataract

geographic atrophy

regions of the retina where cells waste away and die (atrophy), may be seen in dry AMD

anterior blepharitis

seborrhoeic blepharitis, involves the eyelid skin, eyelashes, and associated glands

anomalous retinal correspondence

sensory adaptation when the fovea of one eye has a common visual direction with an extra foveal area of the other eye, instead of suppressing the double image the visual system creates binocular or single vision (interpreting the 2 anomalous points as corresponding)

neural canal

space through which the spinal cord passes, forms the ventricles of the brain & the central canal of the spinal cord

primary angle closure glaucoma

sudden blockage of aqueous humor causes marked increas of the IOP, causing ischemic and permanent damage to optic nerv (II) case:older pt co/o acute onset of a severe frontal headache or sever eye pain with blurred vision and tearing. Seeing halos around lights. May c/o nausea vomiting

trabeculectomy

surgical creation of a drain to reduce intraocular pressure to treat glaucoma

enucleation

surgical removal of the eyeball

pseudostrabismus

the appearance of malallignment due to the presence of epicanthal folds. yet the corneal reflex is normal

rostral neuropore

the cranial opening of the neural tube that closes on the 25th day. closure of the neuropores coincides with the establishment of a blood vascular circulation for the neural tube.

uvela (ocular) melanoma

the most common primary intraocular (within the eye) cancer in adults. It is a disease in which cancer (malignant) cells are found in the part of the eye called the uvea. The uvea contains cells called melanocytes.

Strabismic amblyopia

the tendency of a child's brain to suppress the images from the deviating eye, causing amblyopia

lamina cribosa

thinning, mesh part of sclera where optic nerve fibers penetrate, supporting structure which fills the whole of the back of the eye

inferior rectus

to test you must ask the patient to abduct their eye & look down muscle involved in abduction

superior rectus

to test you must ask the patient to abduct their eye & look up muscle involved in elevation

superior oblique

to test you must ask the patient to adduct their eye then look down this muscle: intorsion, depression, adduction

inferior oblique

to test you must ask the patient to adduct their eye then look up muscle involved in extorsion, elevation & abduction

hypertropia

upward deviation of one eye

hyperphoria

upward drifting of the eye

indocyanine green angiography

used to acquire an angiogram of the choroid, to investigate AMD

spokes

white wedge like opacities that start in the periphery of the lens & work, seen in cortical cataracts