2. Internal Eye Flashcards
(27 cards)
What are the causes and pathophysiology of anterior uveitis
Ae = idiopathic, ank spond, sarcoid, IBD, reactive arthritis, herpes, TB, syphilis
Path =
- Anterior: iris + ciliary body (IRITIS)
- Posterior: choroid (CHOROIDITIS)
- Intermediate: vitrous + panuveitis
How does anterior uveitis present?
S+S =
- red eye
- pain
- blurred vision
- photophobia
- in lacrimation (no sticky discharge)
- small pupil from iris spasm
- irregular pupil dilation due to synechiae (adhesion of lens + iris)
How should anterior uveitis be investigated and managed?
Ix = slit lamp with dilated pupils (leucocytes in anterior chamber)
Mx = urgent eye clinic, control underlying disease, pred drops, cyclopentolate (prevent spasm + synechiae)
What is the retina?
Receives light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition
Outer pigmented layer (in contact with choroid) + inner sensory layer (contact with vitreous), centre of the posterior part lies the macula
Outline the types of retinal detachment and their causes
1) rhegmatogenous retinal detachment
- tear in retina causes fluid to separate sensory retina from pigment ep
- trauma
2) exudative retinal detachment
- detaches without tear
- HTN, vasculitis, macular degenerative conditions
3) tractional retinal detachment
- pulling on the retina
- proliferative retinopathy
How does retinal detachments present?
4 Fs =
- Floaters
- Flashes
- Field loss (central vision lost if macula detached)
- Fall in acuity
***painless and may be curtain falling over vision
How should retinal detachment be Ix and Mx?
Ophthalmoscopy = grey opalescent retina, ballooning forward, extensive detachment will pull off the macula
Mx = rest, lie flat if detachment superior, lie 30 degrees heads-up if detachment inferior, laser photocoagulation therapy, vitrectomy and gas tamponade, scleral silicone implants
Outline central retinal artery occlusion
Occlusion is often thromboembolic (carotid A atherosclerosis)
- much less common than retinal V occlusion
- considered form of stroke
S+S = SUDDEN vision loss within seconds of occlusion, PAINLESS, signs of stroke (bruits, in BP), AF, heart valve disease, DM, smoking, in lipids
Ix =
- USS carotids
- Fundoscopy:
- Central A = widespread oedema (retina white), cherry red spot in macula (still gets blood from underlying choroid)
- Branch = localised area of retinal oedema
Mx = in retinal blood flow, reduce IOP by ocular massage, surgical removal of aqueous from anterior chamber, intraocular hypotensive Tx
- Mx thromboembolic RF
- Refer to stoke team for full work-up
Outline relative afferent pupillary defect (RAPD)
- sign observed during swinging-flashlight test
1) light directed in affected eye causes mild constriction of both pupils (due to decreased response to light from afferent defect)
2) light in unaffected eye causes normal constriction of both pupils (due to intact efferent path, and intact consensual pupillary reflex)
Ae = INCOMPLETE optic N lesion: glaucoma, MS, optic neuritis, optic N tumours (glioma, meningioma), trauma, retinal detachment
- Mild = weak pupil constriction, followed by dilation
- Moderate = pupil size will remain, after which it dilates
- Severe = pupil will dilate quickly
Describe amblyopia
Eye fails to achieve normal visual acuity
‘lazy eye’ = brain fails to process inputs from one eye and over time favours the other eye, results in decreased vision
Ae = any condition that interferes with focusing (poor alignment, irregularly shaped, nearsighted or farsighted, clouding of the lens)
Mx = treat underlying cause, glasses, eye patch (works until 7/8y)
What terminology is used to describe strabismus?
Squint - eye misaligned
ESO - turning in
EXO - turning out
Hyper - up
Hypo - down
Concomitant - amount of diversion remains constant in all directions of gaze
Inconcomitant - angle of squint varies with gaze (tend to be CN palsy)
Phoria - eye deviate only when fusion blocked (latent) (SOMETIMES)
Tropia - visual axis of each eye do not intersect at point of fixation (manifest) (ALWAYS)
How should strabismus be Ix?
Orthoptic assessment
Fundus
Bloods
Scan
Hirschbergs Test = looking for light reflection to fall in the centre of the pupil, every 1mm is 7 degrees deviation
Cover Test
What are the causes of strabismus?
Congenital - within 6m (unknown)
Refractive errors - anisometropia (one eye v diff prescription to other), myopia, hypermetropia, astigmatism
Other - tumour (retinoblastoma), cerebral palsy, down syndrome
How should strabismus be Mx?
Patching good eye (reduce amblyopia) - improves vision not the squint (corrected later with surgery)
Specs (+/- prisms)
Surgery (muscle resection, recession)
Tx underlying cause
Outline CN IV (4) palsy
Innervates superior oblique (SO) muscle
S+S =
- Lose of normal action = eyeball held extorted, up + in
- Compensate by tilting head to contralateral side
- Report diff looking down medially (walking down stair, reading) - diplopia worse
- Diplopia (when head straightened from tilt)
- hypertropia (superior oblique not pulling down, sits higher up)
- WOOG (hypertropia worse on opposite gaze)
- BOOT (better on opposite tilt)
Ae = vasculopathic, tumour, congenital, trauma, thyroid eye disease
Outline CN VI (6) palsy
Innervated lateral rectus (LR)
S+S =
- Unopposed pull of medial rectus muscle (esotropia)
- Unable to Abduct eye on affected side
- Diplopia - worst when looking to effected side
Ae = DM, HTN, stroke, acoustic neuroma (corneal sensation loss earliest sign), RICP
Ix = HbA1c, BP, ESR, MRI (younge pt, exclude SOL, demyelination), AChR Ab, MuSK Ab
Mx = prism, cover one eye (large deviation), review 4-6w
Outline CN III (3) palsy (down and out syndrome)
Ocular muscles = SR, IR, MR, IO
- Adduction + vertical eye movements reduced
- DOWN + OUT position
Innervates levator palpebrae = loss = PTOSIS
Parasympathetic to sphincter pupillae = loss = dilation (MYDRIASIS)
- PS fibre on the outside, compression from outside (tumour, aneurysm) will show dilation early (CT angiogram)
- Reaction to light absent or reduced
Patient complains of diplopia if eye held open (assuming both eyes can see)
Can be painful
Ae =
- Pupil involved = aneurysm (interpeduncular fossa - MRI), tumour
- Pupil sparing = microvascular, GCA, MG, ischaemia (DM, HTN, hyperlipidemia)
Ix = AChR Ab, MuSK Ab, CTa
What are the types of refractive error (visual impairment)?
MYOPIA (short sight) - light focused in front of retina
- long axial length
- high power cornea, average axial length
- corrected with = concave lens (EXPANDS light before enter eye)
HYPERMETROPIA (long sight) - light focused behind retina
- short axial length, average cornea
- low power cornea, average axial length
- corrected with = convex lens (CONVERGES light before enter eye)
ASTIGMATISM (burred at any distance) - light focused in front and behind
- rugby ball shaped with 2 axis mean 2 images
- corrected with = 2 lens (1 brings the image forward, 1 pushes the image back)
PRESYOPIA (old eye)
- declining amplitude of accommodation with age
- can be variable throughout the day
- corrected with = reading glasses or bifocal/varifocals
What are the common causes of visual impairment in diff age groups?
CHILDREN = optic atrophy, cataract, congenital glaucoma
ADULTS = DM retinopathy, uveitis, macula dystrophies
ELDERLY = cataract, glaucoma, ARMD
How should suspected refractive error be Ix?
Pinhole screening test = improvement in vision indicates probable uncorrected refractive error
- width of ray of light reduced so size of image on retina reduces, so blur reduced
How should visual impairment be managed?
Focus = lenses that correct refraction
Distance vision = telescope devices
Reading vision enhancement = optical devices
Near vision enhancement = electronic devices
Outline an afferent pupillary defect
Complete optic N lesion
S+S =
- affected pupil stim: neither eye reacts
- normal pupil stim: both eyes react
- involved eye is blind
What is adie’s (tonic) pupil
Ae = viral infection, trauma, vasospasm due to migraine, ocular surgery, tumour
Path = damage to parasymp fibres innervating pupil constrictor muscle with cell bodies in the ciliary ganglion
S+S = pupil abnormally dilated at rest, poor/sluggish pupillary constriction in bright light
What are the 4 common causes of unequal pupil?
SMALL
- Horners syndrome
- Tonic pupil
LARGE
- 3rd N palsy
- acute glaucoma
- pharmacological pupil
- Holmes Adie pupil
