Eye Review Flashcards by Srishti D

What shape is the orbit?

Pyramid

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Where do nerves and vessels enter the orbit?

Apex

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How many bones make up the orbit?

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What proportion of the orbit is the eye?

20%

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What is the main arterial supply of the orbit?

Ophthalmic artery

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What is the venous drainage of the orbit?

Superior and inferior ophthalmic veins

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Which bone is frequently involved in blow-out fractures of the orbit?

Maxilla - part of floor

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What does the lacrimal gland secrete?

Aqueous layer of tear film

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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

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What is Muller’s muscle and what does it do?

Also known as superior tarsal muscle - smooth not striated

Helps lift eyelid

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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

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What are Zeiss glands?

Sebaceous glands on margin of eyelid

Secrete into hair follicle of eyelashes

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What are Moll glands?

Apocrine glands on margin of eyelid

Secrete into hair follicle of eyelashes

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What are the lacrimal puncta?

Openings in medial portion of eyelid to lacrimal canaliculi and sac

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What is the sclera?

Tough fibrous wall of eye

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What is the conjunctiva?

Clear mucous membrane lining inside of eyelids and sclera

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What is the limbus?

Where sclera and cornea meet

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What are the layers of the cornea from anterior to posterior?

Epithelium
Bowman's layer
Stroma
Decemet's membrane
Endothelium

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What is the sensory innervation of the cornea?

Ophthalmic division of CN V

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What is the blood supply to the cornea?

Avascular

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What is the anterior chamber full of?

Aqueous humour

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What produces the aqueous humour?

Ciliary body

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How does aqueous humour drain out of the eye?

Canal of Schlemm > trabecular meshwork

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What makes up the uveal tract?

Iris
Ciliary body
Choroid

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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