opthomology Flashcards
what are the 3 layers of the eye?
- outer fibrous layer
- middle vascular and pigmented layer (uvea)
- inner nervous layer
structures of outer fibrous layer of eye?
-sclera and cornea
what is the outer fibrous layer of the eye responsible for?
-refraction (sclera and cornea are part of the outer fibrous layer)
what is the middle vascular and pigmented layer of the eye made up of?
- ciliary body
- iris
- choroid
what is the inner layer of the eye made up of?
retina
which layer of the eye is most vascular?
middle
which layer of the eye is most photosensitive?
inner (contains the retina)
what nerve supplies the orbicularis oris?
CN VII
what nerve supplies the levator palpabrae superioris?
CN III
what type of nerve fibres innervate the superior tarsal muscle
sympathetic fibres
what nerve innervates the lacrimal gland?
CNVII
what nerve innervates the ciliary muscles?
CN III
what nerve innervates the constrictor pupillae?
CNIII
what nerve innervates the dilator pupillae?
-sympathetic nerves
role of ciliary muscles?
change lens shape
-contraction leads to relaxation of suspensory muscles therefore thickening the lens and making it more rounded (allowing you to see close up)
what muscles affect pupil size?
- constrictor pupillae
- dilator pupillae
what are the afferent and efferent blink nerves?
blink afferent- V1
blink efferent- CNVII
what nerves control lacrimation?
sympathetic (emotional) parasympathetic CNVII (cleaning)
role of superior rectus?
- elevation
- adduction and medial rotation
role of inferior rectus?
- depression
- adduction and lateral rotation
role of lateral and medial rectus?
lateral- abduction
medial- adduction
role of superior oblique?
- depress
- abduct and medial rotation
role of inferior oblique?
- elevate
- abduct and lateral rotation
presentation of CNIII palsy?
- down and out eye
- ptosis (drooping eyelid)
- dilated non reactive pupil
- unopposed lateral rectus (innervated by abducens) causes exotropia and superior oblique (innervated by trochlear) causes hypotropia
- CNIII innervates levator palpebrae superioris which is responsible for lifting the eyelid
- constrictor pupillae is innervated by CNIII
presentation of CN VI palsy?
- medially/ inward
- Esotropia
- often have diplopia
This is due to lateral rectus which controls abduction being innervated by CN VI
what can cause a 6th nerve plasy?
- often raised ICP
- acoustic neuroma
how does trochlear nerve palsy present?
- up and in eye
- esotropia
- vertical diplopia
- patients will often present with a head tilt to counter
what does damage to 1 cause?
right anopia
what does damage to 2 cause?
+ what can cause damage to 2?
bitemporal hemianopia
-pituitary tumour
what does damage to 3 cause?
+ what could cause this
left homonymous hemianopia
-stroke
what does damage to 4 cause?
superior left quadrantopia
PITS
Parietal- inferior quadrantopia
Temporal- superior quadrantopia
what does damage to 5 cause?
-left homonymous hemianopia
what does damage to 6 cause?
-inferior left quadrantopia
PITS
parietal= inferior
Temporal= superior
what is red?
retinal vein
what is red?
retinal artery
what is red?
optic disc
what is red?
optic cup
what is red?
fovea
what is red?
macula
what causes open angle glaucoma?
- increased resistance through trabecular meshwork making passage of aqueous humour more difficult
- this leads to a slow build up of ICP
risk factors for open angle glaucoma?
- afro carribean
- diabetes
- hypertension
- steroid use
- myopia (near sightedness)
- increase of age
opeN= Near sighted
presentation open angle glaucoma?
- gradual onset vision loss (begins peripherally + often bilateral)
- fluctuating pain, headaches, blurred vision
- HALOS around lights (especially at night)
SIGNS:
- decreased visual acuity
- increased intraocular pressure
- optic disc increases in size
investigations for open angle glaucoma?
visual field assessment and acuity:
-peripheral vision loss and decreased acuity
Fundoscopy:
-optic disc increases in size
Tonametry:
-intraocular pressure increased
treatment for open angle glaucoma?
First line= latonoprost (prostaglandin analogue)
- BB (e.g. timolol)- AVOID IS ASTHMATICS
- Carbonic anhydrase inhibitors (e.g. Dorzolamide)
- Sympathomimetics (e.g. Brimonidine)
Surgery- trabeculectomy
Latonoprost= Lid= open a lid
what causes acute angle closure glaucoma?
- optic nerve damage due to acute raised intracranial pressure
- the iris bulges forwards, preventing the passage of aqueous fluid from the anterior chamber, increasing intracranial pressure
presentation acute angle closure glaucoma?
- rapid onset vision loss (often unilateral)
- painful, red, teary eye
- semidilated pupil
- nausea
- halos around lights
investigations for acute angle closure glaucoma?
visual field assessment and acuity:
- decreased visual acuity
- dilated fixed pupil
Fundoscopy:
-increase in size of optic disc
Tanometry:
-increase in intraocular pressure
management of acute angle closure glaucoma?
URGENT REFERRAL
- Pilocarpine eye drops (Closure- piloCarpine)
- IV acetazolamide (carbonic anhydrase inhibitor)
Surgery is definitive treatment= laser iridotomy
role of pilocarpine?
acts on muscarinic receptors causing Pupil Constriction and ciliary muscle contraction
PiloCarpine- Pupil Constriction
role of carbonic anhydrase inhibitors?
-reduce production of aqueous fluid
what is dry age related macular degeneration?
- most common cause of blindness in the UK
- caused by degeneration of the macula
risk factors for dry age related macular degeneration?
- advancing age
- smoking history
- caucasian/ chinese origin
- family history
- ischaemic heart disease
more common- dry or wet ARMD?
dry (90%)
presentation of dry ARMD?
- gradual worsening of central vision
- reduced visual acuity (usually bilateral)
- wavy appearance of lines
investigations for dry ARMD?
snellen chart:
-reduced visual acuity
Amsler Grid test:
-shows distortion of straight lines
Fundoscopy/slit lamp:
-drusen visualised between Bruch’s Membrane and retinal pigment epithelium
Optical Coherence Tomogrophy:
-used to assess progression
treatment dry ARMD
- no specific treatment
- avoid smoking, BP control, vitamin supplementation
presentation wet ARMD?
- acute onset vision loss
- reduced visual acuity
- wavy appearance of lines
- especially bad at night
- struggle to see things near
SIGNS:
- drusen
- neovascularisation
what test is critical in diagnosing wet ARMD?
optical coherance tomography
treatment of wet ARMD>
anti veg F injections
presentation of cataracts?
- gradual onset vision loss (unilateral)
- starbursts around lights
- loss of red reflex
investigations for cataracts?
- snellen chart
- examination/ fundosopy (shows loss of red reflex)
- slit lamp (visible cataracts)
- blood tests are worth while in younger patients
risk factors for cataracts?
- smoking
- alcohol
- diabetes
- increase in age
- LONG TERM STEROID USE + HYPOCALCAEMIA
management cataracts?
- monitor and manage conservatively in early stages (stronger glasses)
- lens replacement surgery (will eventually be required)
when is diabetic retinopathy classes as proliferative?
when there is neovascularisation
what type of diabetes is proliferative retinopathy more common in?
Type 1 diabetes
what is mild non proliferative retinopathy?
1 or more microaneurysms
role of latonoprost?
- increases uvescleral outflow
- prostaglandin analogue
what is classed as moderate non proliferative diabetic retinopathy?
- microaneurysms
- blot haemorrhages
- hard exudates
- cotton wool spots
what is classed as severe diabetic retinopathy?
-blot haemorrhages and micro aneurysms in 4 quadrants
OR
-venous beading in 2+ quadrants
OR
-any intraretinal microvascular abnormality
what is classed as diabetic maculopathy?
- any visible changes in the macula
- more common in type II DM
management of diabetic retinopathy?
-optimise glycamemic control, BP and hyperlipidaemia
If severe: panretinal laser photocoagulation
Proliferative disease or maculopathy: intravitreal anti VEGF injections
what is papilloedema?
-optic disc swelling caused by a raised intracranial hypertension