Ophthalmology Flashcards
Name the structures light travels through to make an image on the retina
Tear film-> conjuntiva->cornea-> aqueous humour-> lens-> vitreous-> retina
Name the layers of the retina
Nerve fibre layer
Photoreceptors
Retinal pigment epithelium
Difference between two types of photoreceptor cells
Rods: diffuse, black and white and dim settings
Cones: colour vision, mainly in macula
Name the 7 bones that make up the orbit
Frontal, zygomatic, maxillary, lacrimal, ethmoid, palatine, sphenoid
Name the extraocular muscles supplied by the oculomotor nerve
Superior rectus, Inferior rectus, medial rectus, inferior oblique and levator palpebrae superioris
Name the extraocular muscles supplied by CNIV
Superior oblique
Name the extraocular muscles supplied by CNVI
Lateral rectus
What happens in 3rd nerve palsy?
‘Blown pupils’
Fixed down and out position of eyes
ptosis on affected side
Name the layers of the eyelid from anterior to posterior
Skin Orbicularis oculi muscle Tarsal plate and Muller's muscle Meibonian glands Conjunctiva
What nerve supplies sensation to the eyelids?
CN V1 (ophthalmic)
Describe the drainage route for tears
Puncta Canaliculi Lacrimal sac Nasolacrimal duct Nasopharyngeal canal
What does the tear film consist of?
Ant->post
Lipid (from meibonium gland)
->aqueous (from lacrimal gland)
->mucin (from conjunctiva)
What is the average thickness of the cornea?
550µm
Name the layers of the cornea (ant->post)
Epithelium Bowman's Stroma Decemet's Endothelium
What does parasympathetic innervation do to the pupil and lens?
Contracts sphincter pupillae to constrict pupil
Relaxes zonules of ciliary body, lens becomes more rounded (accommodation)
Describe the passage of aqueous humour
From ciliary body
Through pupil into anterior chamber and angle
Through trabecular meshwork to canal of Schlemm
Into veins
Where do the optic nerves synapse?
Lateral Geniculate Bodies in the occiptal lobe
Which fibres do not cross at the optic chiasm?
The temporal retinal branches
What is emmetropia?
No refractive error
Light is focussed on the retina
What is myopia?
Short sightedness, light focusses in front of retina
How do you correct myopia?
Concave lens
What is hyperopia?
Long sightedness
Light is focussed behind the retina
How do you correct hyperopia?
Convex lens
What is presbyopia?
The lens hardens with age, less able to accommodate
Need reading glasses for near vision