Ophthalmology Flashcards
normal eye pressure
11-21mmHg
what happens in posterior vitreous detachment
caused by natural changes to the vitreous gel with age - it shrinks and develops pockets of liquefaction (think gelatin dessert)
at some stage it may peel away from retina
symptoms of posterior vitreous detachment
photopsia (flashes of light) in the peripheral field of vision
sudden dramatic increase in floaters - often on the temporal side of the central vision
what is PVD more common in
myopia - eye is too long
retinal tear
retinal develops small gaps - can cause retinal detachment in rare cases. caused by ageing or injury
symptoms are mild - may see black spots or floaters and cause distorted vision
retinal detachment symptoms
floaters, flashes of light
loss of central vision - dense shadow that starts peripherally progresses towards the central vision
straight lines appear curved
painless
treatment of retinal detachment
not always required unless there is tears – symptoms gradually improve over 6 months
cryotherapy (freezing) or laser photocoagulation are occasionally used alone to wall of the areas of detachment so that it does not spread
or scleral buckle surgery or pneumatic retinoplexy or vitrectomy
85 percent of cases will be successfully treated with one operation with the remaining 15 percent requiring 2 or more operations. After treatment patients gradually regain their vision over a period of a few weeks
vitreous haemorrhage
o Leakage of blood into the areas in and around the vitreous humor
Large bleeds cause sudden visual loss
Moderate bleeds may be described as numerous dark spots
Small bleeds may cause floaters
o Causes include diabetic retinopathy, trauma, retinal tear or detachment, posterior vitreous detachment
o Treatment – advised to rest with head elevated, can put patch over eye to limit movement, stop blood thinners, retinal tears should be closed by laser treatment or cryotherapy and detached retinas should be reattached
causes of transient visual loss
unilateral
- amourosis fugax (can be one or both). embolic, haeodynamic, ocular, neurologic, idiopathic
- giant cell arteritis can cause double vision or partial loss of vision (treat with high dose prednisolone)
bilateral
- TIAs
- migraine
causes of double vision
binocular - strabismus, nerves (MS, GB, diabetes), stoke, muscle (MG, Grave’s)
monocular - cataract
primary angle closure suspect (PACS)
here goinoscopy shows some closure but the person has normal IOP and no signs of glaucoma
pressure in acute angle closure glaucoma
ophthalmic emergency
sudden risk of pressure to >50mmHg
risk factors for acute angle closure glaucoma
female asian hyermetropia because of shallower anterior chambers (smaller eye) FHx age
the attack is more likely to occur under reduced light conditions when the pupil is dilated
acute angle closure glaucoma presentation
sudden onset of a red painful eye and blurred vision
and patients become unwell with N+V
the cornea is hazy and the pupil is semi-dilated
gets halos around lights (rainbow-coloured)
investigations for acute angle closure glaucoma
goinoscopy -definitive test - trabecular meshwork won’t be visible
slit lamp exam - will see shallow anterior chamber and large optic cup (NB goinoscopy is usually performed at the slit lamp)
automatic static perimetry using Humphrey’s visual field test to check for the amount of glaucomatous visual field loss during initial diagnosis
treatment of acute angle closure glaucoma
URGENT
lie flat with their face up and head not supported by pillows
IV acetazolamide 500mg to reduce IOP (CA inhibitor) and pilocarpine 4% drops to constrict the pupil and to prevent iris adhesion to trabecular meshwork
other topical drops like beta blockers (timolol) and prostaglandin analogues can also be instilled if available
DEFINITIVE TREATMENT = laser iridotomy after initial corneal oedema resolves
the unaffected eye is also usually treated
most common type of glaucoma
primary open angle glaucoma
risk factors for primary open angle glaucoma
FHx high myopia (short-sightedness) DM age (subtle changes in structure of trab mw occur) 2x more common in black steroids HTN CV disease
reduced drainage of aqueous humour from the anterior chamber
vision loss in primary open angle glaucoma
peripheral occurs first
presentation of primary open angle glaucoma
usually asymptomatic and insidious in onset - e.g. picked up by routine eye exam
usually affects both eyes
visual loss only noticed when advanced - peripheral
investigations for primary open angle glaucoma
tonometry - Goldmann tonometry to determine IOP
direct ophthalmoscopy to view cup to disc ratio
indirect opthalmoscopy can also show cup to disc ratio
slip lamp exam is most frequent method used - IOP can be measured and drainage angle assessed
visual field testing should be done on all - scotoma with either an elevated IOP or enlarged cup to disc ratio have high sensitivity and specificity
primary open angle glaucoma treatment
topical prostaglandin analogues e.g. latanoprost or topical beta blocker like timolol
2nd line treatments include CA inhibitors, alpha 2 adrenergic agonsits or a combination
if eye drops fail, surgery can be done like laser trabeculoplastyto improve drainage
PAOG blindess
deveops in 5-10%
pathophysiology of diabetic retinopathy
hyperglycaemia damages retinal pericytes which results in weakening of cap walls and increased blood flow leading to microaneurysms at areas of weakness
it also means vessels are more leaky to proteins and lipids leak out forming hard exudates
= pre-proliferative stage (typically 15 years after diagnosis and can last a few years before becoming proliferative)
at proliferative stage, there is vascular prolideration and most patients will have at least blurry vision or floaters
vision loss in diabetic retinopathy
gradual loss of vision - central - due to macula oedema
or can get sudden loss of vision due to vitreous haemorrhage
cotton wool spots
represent the arrest of axoplasmic material at the margin of a microvascular infarct - thought to represent nerve fiber layer infarct
they are predictive to the progression to PDR
eye palsies
CN3 = down and out CN4 = down and in CN6 = in
investigations for diabetic eye disease
ocular movements to detect any ocular motor palsies
check red reflex due to increased risk of cataracts
visual acuity
photographs at fundus at baseline
optical coherence tomography scanning to show macular oedema or retinal thickening
fluorescein angiography to identify macular leakage
B scan US to identify retinal detachment with vitreous haemorrhage
grading of diabetic retinopathy
R0 = no retinopathy R1 = background R2 = pre-proliferative R3 = proliferative (A = active, S - stable, P - previous photocoagulation laser treatment)
M0 = no maculopathy M1 = maculoapthy present
treatment for clinically signification macular oedema (CSMO)
intravitreal anti-VEGF +/- macular laser therapy
Anti-VEGF include ranibizumab and bevacizumab
macular laser is used to seal the blood vessels around the macular that are leaking and causing the oedema
development of new blood vessels in diabetic retinopathy treatment
pan-retinal photocoagulation
where a laser is used to cauterise ocular blood vessels
is aimed at preventing serious complications like vitreous haemorrhage and retinal detachment
severe proliferative diabetic retinopathy treatmnet
vitrectomy - some or all of the vitreous gel is removed in order to clear the blood from the vitreous humour - is used if bleeding is recurrent and §preventing pan retinal photocoagulation laser therapy
classification of cataracts
nuclear sclerotic - commonest
cortical
posterior or anterior sub-capsular
- posterior is seen frequently due to drugs e.g. topical corticosteroids or metabolic cataracts
- anterior is seen in blunt traumatic injuries
presentation of cataracts
gradual blurred/cloudy/misty vision and glare
in nuclear cataracts, can get washed-out colour vision
investigations in cataracts
test visual acuity
dilated fundus exam with an opthalmoscope - fundus and optic nerve should be normal. will see reduced red relfex and opacification of lens
measure IOP - should be normal - gold standard is via Goldmann applanation tonometry
slit lamp exam of the anterior chamber will allow better visualisation of the cataract
cataract surgery
done once person has functional visual impairment
done as a day case under LA
incision at the corneascleral junction approx 4mm
capsulorhexis - removal of the anterior lens capsule
high speed ultrasonic vibrating tip cuts nucleus into smaller fragments and aspirates them (phakoemulsification)
aspiration of soft lens matter
insertion of posterior chamber IOL (intraocular lens) into capsular bag
post operative treatment is with topical steroids and topical Abx
complications of cataract surgery
rupture of posterior lens capsule causing vitreous loss - if this occurs before the lens nucleus is removed = dropped nucleus - will require another operation to remove it
endophthalmitis = 0.1% risk - commonest organismis staph epidermis
posterior capsular opacification - a healing response that can be corrected by laser treatment - is where the back of the lens becomes cloudy causing blurred vision
what is age related macula degeneration
characterised by degeneration of retinal photoreceptors that results from the formation in drusen
usually bilateral
the drusen occur beneath the retinal pigment epithelium within Bruch’s membrane
drusen alters the permeability of Bruch’s membrane resulting in decreased nutrient delivery to RPE cells and secondary metabolic stress
risk factors for AMD
smokers have a 2-3x increased risk
FHx
genetic factors
symptoms of AMD
distortion is usually the first symptom - straight lines appear crooked or wavy
gradual loss of central vision - difficulty with reading + recognising faces
wet type: if associated with haemorrhage may have sudden deterioration
eventually severe central field loss but maintain peripheral vision
AMD investigations
visual acuity - may be normal or reduced
fundoscopy + photography - may see drusen or pigmentary, haemorrhageic or atropic changes affecting the macula
slit lamp - same as above
Amsler grid - distortion (metamorphopsia)
optical corherence tomography - definitive test for confirming presence of subretinal and intraretinal fluid
fluorescein angiography if neovascular AMD is suspected
management of AMD
slow progression by stopping smoking, eat heathily
consider registering as sight impaired
signpost to relevant organisations, sources of info
high-dose antioxidant and mineral supplementation like zinc
for neovascular AMD:
- anti-VEGF like ranibizumab, afilbercept via intravitral injection (monthly for 3 months then variable times thereafter)
- others (although not usually recommended) - laser photocoagulation or photodynamic therapy with verteprofin
an emerging treatment: implantable miniature telescope that focuses the central visual field onto areas of the retina not affected by AMD
3 causes of painless red eye
CES
conjunctivitis
episcleritis
subconjunctival haemorrhage
and blepharitis - but this causes more of a red eyelid rather than eye
hazy cornea, haloes
acute angle closure glaucoma
ciliary flush
anterior uveitis
corneal abscess
contact lens related red eye
cause of blepharitis
anterior = inflammation of the base of the eyelashes. can be caused by bacteria (usually staphylococci) or seborrhoeic dermatitis posterior = inflammation of the meibomian glands
can also be associated with acne rosace
blepharitis presentation
minimal red eye
burning, itching, erythema and crusting of eyelids
no pain, no photophobia, no visual loss
chalazions (cysts in the eyelid due to inflammation of blocked meibomian glands)
management of blepharitis
Eyelid hygiene measures and warm compresses
Consideration of topical antibiotics (such as chloramphenicol) if hygiene measures have failure
stye (hordeolum) vs chalazion
stye = bacterial infection either at the root of the eyelash follicle or in the oil gland of the lids
chalazion = blocked oil gland
chalazion are painless
treatment of entropion
Topical antibiotic to prevent infection. Taping down lower lid (temporary measure). Long term correction with surgical procedure under LA
treatment of ectropion
With lateral tarsal strip operation and lubricating eye drops
3 types of conjunctivitis
viral - adenovrius, herpes simplex, EBV, VZV, enterovirus
bacterial - pneumonococcus, s aureus, haemophilius influenae, moraxella catarrhalis
allergic - can be seasonal (hay fever associated) or non-seasonal (dust mites, pets)
hyperacute conjunctivitis
is a rapidly developing severe conjunctivitis typically caused by infection with Neisseria gonorrhea
symptoms of conjunctivitis
discomfort that may be described as a foreign body or burning sensation
watery or purulent discharge
tender, pre-auricular lymphadenopathy more common in viral
unilateral in bacterial, bilateral in viral
itchiness more common in allergic
allergic might be more red around the eye
HSV conjunctivitis may have vesicular lesions on the eyelid
management of viral conjunctivitis
o Usually resolves within 7 days
o Provision of patient information
o Advise self-care measures such as bathing/cleaning the eyelids, cool compresses, lubricating drops or artificial tears
o Avoid contact lenses
o Inform the person that it is contagious, and they should try to prevent spread of infection to their other eye and other people by
Using separate towels, avoiding close contact (but do not have to exclude from school), wash hands frequently
o Consider discussion with/referral to ophthalmology is symptoms persist for more than 7-10 days after initiating treatment
o Consider swabbing for HSV if they re-attend
management
o Advice the person that most cases are self-limiting and resolve within 5-7 days without treatment. + general hygiene measures by not sharing towels etc.
o Provision of patient information
o Advise self-care measures such as bathing/cleaning the eyelids, cool compresses, lubricating drops or artificial tears
o Avoid contact lenses
o If severe or circumstances that require rapid resolution, then treat with topical antibiotics
o A delayed strategy may be appropriate – advise the person to initiate them if symptoms have not resolved within 3 days
Chloramphenicol 0.5% drops
o Explain red flags for urgent review e.g. reduced visual acuity or photophobia §
antibiotic for bacterial conjunctivitis
chloramphenicol
red flags with conjunctivitis for need of urgent opthalmological assessment
- Reduced visual acuity
- Infection with a herpes virus – requires treatment with oral antivirals
- Marked eye pain, headache or photophobia – always consider serious systemic conditions such as meningitis
- If you suspect gonococcal or chlamydial conjunctivitis
gonococcal vs chamyldial neonatal conjunctivitis
gonococcal in 1st 5 days whereas C trachomatis 3 days – 2 weeks
management of subconjunctival haemorrhage
reassure that it will clear in 2-3 weeks
measure the person’s BP and if raised, manage appropriately
check the person’s INR if they are taking warfarin and manage accordingly
keratitis define
= inflammation of the cornea
an ocular emergency (bacterial)
causes of keratitis
viral (HSV, herpes zoster)
contact lens-associated infection
blepharitis
bacterial (pseudomonas aeruoginosa or staph aureua)
less common - fungal (aspergillus fumigatus or candida albicans)
predisposing factor = compromised corneal epithelium e.g. via corneal abrasions, contact lenses, topical steroids, corneal anasethesia
presentation of keratisis
red eye (conjunctival injection) severe pain - gritty or foreign body photophobia decreased VA discharge
bacterial keratitsi- corneal ulcer (white and fluffy)
herpes simplex keratitis - branching dendritic ulcer with fluorescein
investigations for keratitis
confirmed if a corneal lesion is seen on slit-lamp examination - an epithelial defect can easily be seen after staining the cornea with flueorescein
can measure visual acuity with a Snellen chart
corneal scraping for a culture / viral PCR
consider FBC - may indicate systemic infection or immune compromise
treatment of keratitis
bacterial = topical broad spectrum Abx (ofloxacin) + pain relief + cautious use of topical steroids to reduce scarring (usually 48 hrs after initiation of Abx)
viral - topical gancicliovir or oral acyclovir
contact lens wearers are advised to discontinue wear
foreign body management
Instill topical local anaesthetic and remove FB (+/- rust ring) with cotton wool bud or tip of 21G needle
Instill topical antibiotic and eye pad overnight
Topical antibiotic qds for 1/52 to prevent secondary bacterial infection
corneal abrasion due to infection related to contract lens wear
acanthamoeba
or pseudomonas
corenal abrasion/ulceration diagnosis
fluorescein stain - Fluorescein stains any exposed corneal stroma (yellow-orange) and basement membrane – it does not stain intact conjunctival or corneal epithelium
slit lamp
fundoscopic exam is often difficult as the pupil may be small and person photophobic
colour of fluoroscein stain
uses an orange dye and a blue light – any problems will appear green under the blue light
