Eye Review Flashcards
What shape is the orbit?
Pyramid
Where do nerves and vessels enter the orbit?
Apex
How many bones make up the orbit?
7
What proportion of the orbit is the eye?
20%
What is the main arterial supply of the orbit?
Ophthalmic artery
What is the venous drainage of the orbit?
Superior and inferior ophthalmic veins
Which bone is frequently involved in blow-out fractures of the orbit?
Maxilla - part of floor
What does the lacrimal gland secrete?
Aqueous layer of tear film
What are the main muscles of the eyelid, what do they do, and by which nerve are they innervated?
Levator palpebrae superioris - Opens lid - CN III Obicularis oculi - Closes lid - CN VII
What is Muller’s muscle and what does it do?
Also known as superior tarsal muscle - smooth not striated
Helps lift eyelid
What are meibomian glands?
Special type of sebaceous gland at rim of eyelids inside tarsal plate
Secrete meibum = prevents evaporation of eye’s tear film
What are Zeiss glands?
Sebaceous glands on margin of eyelid
Secrete into hair follicle of eyelashes
What are Moll glands?
Apocrine glands on margin of eyelid
Secrete into hair follicle of eyelashes
What are the lacrimal puncta?
Openings in medial portion of eyelid to lacrimal canaliculi and sac
What is the sclera?
Tough fibrous wall of eye
What is the conjunctiva?
Clear mucous membrane lining inside of eyelids and sclera
What is the limbus?
Where sclera and cornea meet
What are the layers of the cornea from anterior to posterior?
Epithelium Bowman's layer Stroma Decemet's membrane Endothelium
What is the sensory innervation of the cornea?
Ophthalmic division of CN V
What is the blood supply to the cornea?
Avascular
What is the anterior chamber full of?
Aqueous humour
What produces the aqueous humour?
Ciliary body
How does aqueous humour drain out of the eye?
Canal of Schlemm > trabecular meshwork
What makes up the uveal tract?
Iris
Ciliary body
Choroid
What are the two muscles of the iris, and which arms of the autonomic nervous system are they innervated by?
Sphincter muscle > parasympathetic
Dilator > sympathetic
What is the choroid?
Blood supply for outer half of sensory retina
Which vessels feed into the choroid?
Posterior ciliary arteries
What is the blood supply of the lens?
Avascular
What are the layers of the lens?
Capsule > cortex > nucleus
What is a cataract?
Lens opacity
What occupies 80% of the globe?
Vitreous humour
What makes up the vitreous humour?
Complex structure of collagen fibrils
What makes up the visual pathway?
Optic nerve Optic chiasm Optic tract Optic radiation Visual cortex
What are the extraocular muscles, and which nerves innervate them?
Rectus - Medial - CN III - Lateral - CN VI - Superior - CN III - Inferior - CN III Oblique - Superior - CN IV - Inferior - CN III
What are the main causes of visual impairment in Australia, in descending order?
Refractive error
Macular degeneration
Cataract
What is myopia?
Short-sightedness
Light focused before hitting retina
What is hypermetropia?
Long-sightedness
Light focused after hitting retina
What is astigmatism?
Non-spherical curvature of cornea
Regular = 2 different curves at 90 degrees to each other
Irregular = variable degrees of curvature along each axis
Can astigmatism be corrected with glasses?
Regular can, irregular cannot
What is presbyopia?
Loss of lens flexibility with age > long-sightedness
What is glaucoma?
Group of diseases that cause progressive damage to optic nerve
What is the major contributing factor to glaucoma?
Increased intra-ocular pressure
What are the symptoms of acute glaucoma?
Acute pain Redness Blurred vision Haloes around lights Nausea Usually sudden onset
What are the symptoms of open angle glaucoma?
Minimal
What is the normal cup-disc ratio?
0.3
What does an abnormally large cup-disc ratio indicate?
Glaucoma
What are the major clinical features of primary open angle glaucoma?
Progressive visual field loss
Progressive increase in cup-disc ratio of optic disc
Elevated intra-ocular pressure
What are the main causes of cataracts?
Age Congenital Traumatic Secondary Drug induced
What are some diseases common to the retina?
Macular degeneration
Diabetic retinopathy
Vascular occlusions
What are the symptoms of macular degeneration?
Distortion of central vision = metamorphopsia
What are the signs of mild non-proliferative diabetic retinopathy?
Microaneurysms
What are the signs of moderate non-proliferative diabetic retinopathy?
Microaneurysms Intra-retinal Haemorrhages Hard exudates Cotton wool spots
What are the signs of the severe non-proliferative diabetic retinopathy?
Any one feature of 4-2-1 rule
- Intra-retinal haemorrhages in 4 quadrants
- Venous beading in 2 quadrants
- Intra-retinal vascular abnormalities in 1 quadrant
What are the signs of very severe non-proliferative diabetic retinopathy?
Any two features of 4-2-1 rule
- Intra-retinal haemorrhages in 4 quadrants
- Venous beading in 2 quadrants
- Intra-retinal vascular abnormalities in 1 quadrant
What is the classification of low risk proliferative diabetic retinopathy?
Less than 1/3 of disc neovascularised
What is the classification of high risk proliferative diabetic retinopathy?
Neovascularised disc + vitreous haemorrhage
More than 1/3 of disc neovascularised
Neo-vascularisation everywhere
What is the management for proliferative diabetic retinopathy?
Pan-retinal photocoagulation
Burns away areas of peripheral retina
Decreased drive of VEGF production > reduced neovascularisation
Peripheral vision sacrifice
What is the history of retinal venous occlusions?
Sudden, painless unilateral loss of vision
What is the history of central retinal arterial occlusions?
Sudden, painless unilateral loss of vision
What is the main causative factor of central retinal arterial occlusions?
Atherosclerotic changes
What is the main causative factor of branch retinal arterial occlusions?
Embolism
What is the epidemiology of optic neuritis?
Typically young adults = 18-45 years
Female predominance
What are the symptoms and signs of optic neuritis?
Total/partial sudden loss of vision Reduced colour vision Pain - worse on eye movement Usually unilateral Afferent pupil defect
What does optic neuropathy refer to?
Disorders involving ischaemia/toxicity
What is ischaemic optic neuropathy associated with?
Damage to posterior ciliary artery supply to optic neuropathy head > sudden loss of vision
