Anatomy Of The Eye Flashcards
Anatomically, how may the eye be divided
Into 3 layers:
- Fibrous
- Vascular
- Inner
What does the fibrous layer of the eye contain
Sclera and cornea
What is the sclera
White structure comprises 85% of fibrous layer, enables attachment of extra-ocular muscles
What is the cornea
Transparent structure at the front of the eye
What are the 3 components of the vascular layer
- Choroid
- Ciliary body
- Iris
What is the choroid
Blood supply to the retina
What is the ciliary body
Comprised of the ciliary muscle and ciliary process it controls the shape of the lens and produces aqueous humour
What Is the ciliary muscle
Smooth muscle fibres that control shape of the lens
What is the ciliary process
Fibres that connect ciliary muscle to lens
What is the iris
Circular structure with aperture in the centre that enables light to enter. Smooth muscle controls diameter of the iris.
What forms the inner layer of the eye
Retina
What is the retina comprised of
Neural Layer
Pigmented Layer
What is the neural layer
Contains photoreceptors
What is the pigmented layer
Attaches to choroid to help support the neural layer
What is the non-visual retina
Where part of the pigmented layer continues anteriorly without neural layer
What is the optic retina
Neural and pigmented layer
What part of the retina is seen in ophthalmoscopy
Optic retina
What is the centre of the retina called
Macula
How does the macular appear on opthalmoscopy
Yellow
What is in the centre of the macula
Fovea
What does the fovea do
High-visual acuity
Where does the optic nerve enter the eye
Optic disc
What is not located at the optic disc
Photoreceptors
What are the two compartments of the eye
anterior and posterior chamber
What is the anterior chamber of the eye
from lens to cornea
where is the posterior chamber of the eye
iris and ciliary process
what are chambers filled with
aqueous humour
what drains aqueous humour
canal of schlemm - located in the trabecular meshwork
What is the arterial supply to the eye
Ophthalmic artery
Where does the ophthalmic artery arise
Internal carotid artery
What is the most important branch of the ophthalmic artery
Central retinal artery
What is the venous drainage of the eye
Superior and Inferior ophthalmic veins
Where do the superior and inferior ophthalmic veins drain
Cavernous sinus
What are the 3 main presentations for eye conditons
- Red Eye
- Acute visual Loss
- Chronic visual loss
What 4 conditions may present with a red eye
- Conjunctivitis
- Keratitis
- Uveitis
- Acute glaucoma
What 6 conditions may cause acute loss of vision
1. Central retinal artery
occlusion
2. Central retinal vein
occlusion
3. Retinal detachment
4. Stroke
5. GCA
6. Vitreous HaemorrhageWhat 4 conditions may cause chronic visual loss
- Cataracts
- Chronic glaucoma
- Macular degeneration
- Diabetic retinopathy
How many bones form the orbit
7
What two bones form the superior orbit
Sphenoid
Frontal
What two bones form the lateral orbit
Zygomatic
Sphenoid
What is a way to remember bones that form medial orbit
LEMS
What 3 bones form inferior orbit
Maxilla
Palatine
Zygomatic
What 4 bones form medial orbit
Lacrimal
Ethmoidal
Maxillary
Sphenoidal
What is the main blood supply to the eye
Opthalmic.a
Describe origin of opthalmic artery
First branch of the internal carotid artery. It passes through the cavernous sinus
What are the two groups of branches of opthalmic artery
Orbital
Optical
What is the role of the orbital group
Orbital = Innervates structures in the orbit
What is the role of the topical group
Optical = innervates the eye and muscles
What branch of the ophthalmic nerve innervates the retina
Central retinal artery
What branch of the ophthalmic nerve innervate the optic disc
Short posterior ciliary arteries - which innervate the optic disc as circle of zinn-haller
What is the venous drainage of the eye
Central retinal vein
Where does the central retinal vein drain
Cavernous sinus or superior ophthalmic vein
Explain visual pathway
- Optic nerve leaves optical canal and passes to optic chiasm
- At the optic chiasm the peripheral and nasal fields cross over
- The optic tracts then travel to lateral geniculate nucleus of the thalamus
- The fibres that supplied superior retina (Inferior visual field) then travel as Meyer’s loop to primary visual cortex
- The fibres that supplied inferior retina (superior visual field) then travel as Baum’s to primary visual cortex
How is visual acuity recorded
Numerator =chart distance (6m)
Denominator = lowers line read
What does 6/7 on visual acuity mean
This person can see at 6m what someone should be able to see at 7m
Define miosis
Pupil constriction
Define mydriasis
Pupil dilation
What are miotic agents
agents that cause pupil constriction
Name 3 miotic agents
- M3 receptor agonist
- a1 antagonist
- Opioids
Name an M3 receptor agonist
Pilocarpine
Name an a1-antagonist
Tamulosin
What autonomic NS stimulation causes miosis
Parasympathetic
What are mydriatics
Medications that dilate pupil
What are mydriatics also called
Cycloplegics
Why are mydriatics called cycloplegics
As the paralyse ciliary muscles and cause blurring of vision
What are 5 mydriatics
- Anticholinergics
- Antipsychotics
- Antihistamines
- TCAs
- A1-receptor agonists
What anticholinergic is used in eye exam
Tropicamide
How long does tropicamide last
3h
Why do antipsychotics cause pupil dilation
M3 receptor antagonists
Why may anti-histamines cause mydriasis
M3 receptor antagonists
Why may anti-depressantscause mydriasis
M3 receptor antagonists
Name 3 a1-receptor agonists
NA
Cocaine
Amphetamines
