Eye Review (core) Flashcards
What is normal IOP?
10-21mmHg
How does the cup to disc ration change in glaucoma?
It increases
Where does the optic nerve decussate in the brain to cause the consenual response?
Pretectal nucleus
What is the common cause of an altitudinal defect
Anterior ischaemic optic neuropathy
Which viral infection can effect the corneal reflex?
Herpes
What test do you use to evaluate macula function?
Amsler grid
What are leukocoria? What can it indicate?
White pupil
Retinablastoma, cataract, retinal detachment
What are some common causes of 4th nerve palsy?
Trauma
Tumour
Vasculitis
Can be congenital
How can you test the IOP?
Tono-pen
Glodmann Applanation tonometry
What causes an arcuate scotoma?
Glaucoma
What are three ways diabetic retinopathy causes vision loss
Macula oedema
Vitreous detachment
Retinal haemorrhage
What is the normal physiological cup to disc ratio?
0.5
What causes painfull third nerve palsy?
Aneurysm (Post comm art.)
What is the pathophysiology of retinal detachment?
Separation of the inner layers of the retina from the underlying retinal pigment epithelium due to a number of mechanisms
- A tear in the neuronal layer allowing entry of vitreous fluid
- Traction from inflammation or vascular fibrous membranes on the surface of the retina
- Exudation of materials into the subretinal space such as due to HTN, central retinal artery occlusion, vasculitis, or papilloedema
How do you test light saturation?
Compare the appearance of light shined in each eye
Which muscle controls the pupils?
Sphincter pupillae
Which nuclei are involved in the pupil reflex?
The pretectal nucleus
The Edinger-Westphal nucleus
What is Agyll-Robertson pupil? What causes it?
A pupil that constricts to accomodation but not light
Classically neurosyphilis
Also diabetic neuropathy
What does a Holmes Adie pupil look like?
Tonically dilated pupil that doesn’t response to light
How does internuclear ophthalmoplegia present? What is the mechanism? In which disease is it common?
Failure of abduction of one eye when laterally gazing to its contralateral side and concurrent nystagmus of the other eye. Convergence is maintain
Lateral gaze is controlled by the nucleus of CNVI on the ipsilateral side that the gaze is toward. Its signal to the ipsilateral lateral rectus is normal therefore abduction is possible on that side. Abduction of the other eye requires signal transmission from the CNIV nuclei to the contralateral CNIII nuclei (and subsequent CNIII innervation of the medial rectus). The medial longitudinal fasciculus transmits between CNVI and CNIII. In INO the MLF is disrupted.
Convergence is retained as it doesn’t require the lateral rectus (and hence CNVI)
MS
What is myopia? What do they have trouble with? What type of correction do they use?
Light is focus before the retina - Short sightedness
Deficit - Think short sighted meaning can seeing objects at a short distance therefore have trouble with seeing objects at distance eg road signs
Biconcave lens
What hypermetropia? What do they have trouble with?
Light is focused beyond the retina - Long sightedness
Deficit: Long sighted meaning able to see things at a distance therefore trouble with focusing at close objects eg reading
Biconvex lens
What is astigmatism?
The cornea has irregular degrees of curvature
What is a presbyopia?
A form of hypermetropia due to loss of lens elasticity with age
What is primary open angle glaucoma? How does it present? How is it Mx?
Chronic, progressive optic neuropathy with open anterior chamber angles, and elevated IOP
Progressive visual field loss, progressive increase in cup to disc ratio and elevated IOP
Prostaglandin, timolol eye drop
Oral acetazolamide
Surgery
Outline the grading system of non-proliferative diabetic retinopathy
Mild - Microaneursyms
Moderate - Microaneursyms
- Cotton wool spot
- Hard exudates
- Intra-retinal haemorrhages
Severe - any one feature of the 4-2-1 rule
- Intra-retinal haemorrhages in 4 quadrants
- Venous beading in 2 quadrants
- Intra-retinal vascular abnormalities in 1 quadrant
Very severe - 2 features of the 4-2-1 rule
Outline the types of proliferative diabetic retinopathy
Low risk - neovascularisation in <1/3 of the disc
High risk - Neovascularisation of disc + vitreous haemorrhage
- >1/3 of NVD
- Neovascularisation everywhere
How is proliferative diabetic retinopathy Mx?
Pan-retinal photocoagulation - peripheral vision sacrificed
VEGF inhibitors
What is the pathophysiology of dry aged related macular degeneration? How is it Mx?
Degeneration of the retina and choroid in the posterior pole either due to atropy or detachment of the retinal pigment epithelium. Preceded by the presence of drusen desposition at the basal RPE
Smoking cessation
Low vision aids
What is the pathophysiology of wet macular degeneration? How is it mx?
Proliferation of vasculature between the choroid and retinal pigment membrane which leaks and bleeds causing macular scarring
VEGF inhibitors
Photodynamic therapy
Which causes of a CNIII palsy spare the pupil and which don’t?
Do - Vascular - HTN, DM
Don’t - Compressive - Mass lesion, aneurysm, haemorrhage
What are some DDx for a CNVI palsy?
MG
Medial wall blow out fracture
Thyroid eye disease
How does macular degeneration present on Hx and Ex?
Metamorphopsia
Central scotoma
Distortion on amsler grid
