Opt - Lec1a - Anatomy Flashcards
Name the 4 anatomical structures involved in tear drainage
Lacrimal puncta
Lacrimal canaliculi
Lacrimal sac
Nasolacrimal duct
Name the gland involved in tear production and how many portions does it consist of
Lacrimal gland
2
How many bones form the adnexa orbit
7 (B1-7)
How many canals and fissures are there in the adnexa orbit and which canal does the optic nerve and blood vessels pass?
C1-3
Through C1
What is Orbital Cellulitis
An infection that spreads to the eye from neighbouring sinuses
What are the extraocular muscles?
Four pairs of recti (R1-4)
Two pairs of obliques (O1-2)
Levator papebrae superioris
What are the common disorders optometrists screen for concerning the extraocular muscles?
Strabismus - refers to ‘squint’
Amblyopia - ‘lazy eye’
What part of the eyelid closes eyes and how does it assist in tear drainage?
Orbicularis oculi
Pumping action on lacrimal canaliculi and sac
Which muscle opens eyes; normally
Wide with fright
Levator palpebrae superioris
Tarsal Muscles
What is the meibomian gland?
Gland in the eyelid that secretes a portion a tears that prevents dry eye
What disorders of the eyelid do optometrists screen for?
Blepharitis - common and sometimes called ‘dandruff’ of the eyelid
Chalazion - common eyelid lump caused by infected eyelashes or glands
Ectropion - eyelid is turned out and can occur with age and lead to damage of the eye surface
What is the conjunctiva and why is it important?
Mucosal Epithelium that forms continuous sac over the sclera (White of the eye) and the inner surface of the eyelids
Why it is not possible to lose a contact lens around the back of the eye
Secretes mucus that lubricates the eyes surface
Name 2 conjunctival disorders optometrists screen for
Conjunctivitis - commonly occurs due to dry eye, allergy and viral or bacterial infection
Pinguecula - common age related and harmless degeneration of the conjunctiva (seen as areas of yellowing on older eyes)
Which part of the eye has the most refractive power?
Cornea - why laser refractive surgery is so effective - reshape so the cornea to correct refractive errors
Describe 3 of the anatomical layers of the cornea
Epithelium - has rapid healing properties ( :) contact users)
Stroma - thickest layer - regular collagen fibres which ensure transparency
Endothelium - thinnest layer - regulates water content maintaining transparency
How do optometrists measure corneal shape?
Keratoscopy/Keratometry
What is Keratitis?
Inflammation of the cornea
What is the Sclera?
And why can it appear - a. Bluish and b. yellowish
White part of fibrous layer of the eye consisting of 3 layers including the episclera (containing lots of blood vessels) and stroma (thickest layer, irregular collagen fibres therefore opaque) and the lamina fusca (innermost zone made up of elastic fibres)
Bluish in young children because sclera is thin or possibility of collagen disease
Yellowish in elderly (lipid deposits) or possibility of jaundice
What sclera disorders do optometrists screen for?
Episcleritis - harmless form of red-eye
Scleritis - painful and more serious form of red-eye that can threaten sight
What is the transition zone between the cornea and sclera called and what is its role?
Limbus or Trabecular meshwork
Involved in aqueous humour drainage. Aqueous humour is like transparent blood that feeds cornea and crystalline lens
What Limbal disorders do optometrists screen for?
Tonometry - method of checking intra-ocular pressure that rises if the trabecular meshwork is blocked
Glaucoma - results from blockage of the trabecular meshwork
Which layer of the eye is the Iris a part of?
Vascular layer
Name the muscle involved in MIOSIS (constriction of the pupil)
Sphincter Pupillae
Name the muscle involved in MYDRIASIS (dilation of the pupil)
Dilator Pupillae
What is the role of the ciliary muscle?
Smooth muscle that brings about accommodation (allows eye to focus) via attachments to the crystalline lens
What is the role of the ciliary processes?
Secrete aqueous humour
Some anti-glaucoma drugs reduce aqueous humour production from the ciliary body
What is Anterior Uvetitis
Very serious form of painful ‘red-eye’ that may involve the ciliary body
Occurs with iritis
What are the 3 layers of the Choroid?
The posterior part of the vascular layer of the eye
Bruch’s membrane - passes material to and from retina
Vascular layer = contains numerous blood vessels that bring nourishment to the retina
Suprachoroid - contains melanin to absorb stray light
Disorders that may affect the choroid include
Choroiditis - occurs with posterior uveitis and is a threat to sight
Macular degeneration - may arise from disfunction of Bruch’s membrane
Name 3 key components of the crystalline lens
Lens capsule - governs shape changes that occur during accommodation
Cortex - youngest lens fibres
Nucleus - oldest lens fibres
How is the transparency of the crystalline lens maintained?
Crystallins - soluble proteins
Regular arrangement of lens fibres
Lack of cellular organelles
Antioxidants
Name 2 common disorders of the crystalline lens
Cataract - occurs when mechanisms that maintain transparency fail
Presbyopia - Occurs when the lens can no longer bring about accommodation therefore reading glasses required
What is the role of the Vitreous body
It is a transparent gel that mechanically supports crystalline lens and retina
Has a refractive component
What are the 2 disorders of the Vitreous body that are associated with “floaters”
VITREOUS SYNERESIS - commonly occurs when the vitreous starts breaking down with age
POSTERIOR VITREOUS DETACHMENT - occurs when the vitreous body comes away from the back of the eye leading to a large floater
reports of flashes of light could indicate possible retinal tear or detachment
Name and give the role of the 4 types of cells present in the retina
Rods - predominate in periphery
Cones - predominate in fovea
Bipolar and ganglion cells integrate and process photoreceptors signals
The optic nerve head is the route by which
Ganglion cell nerve fibres take visual signals from eye to brain
Central retinal arteries enter eye
Central retinal veins leave eye
Why is the optic nerve head a physiological blind spot?
And how is it typically shaped?
Because photoreceptors are absent
Cupped
Name 2 common disorders that might cause optic nerve damage
Glaucoma - may cause exaggerated cupping of the optic nerve head
Brain disease - may cause optic. Nerve swelling or pallor
The ocular adnexa include all EXCEPT: A. Extraocular muscles B. Conjunctiva C. Lacrimal gland D. Cornea E. Eye-lids
Cornea (? Check paper copy of lecture)
Is this statement true or false?
Contraction of the sphincter Pupillae brings about MYDRIASIS
False - Contraction of the sphincter Pupillae brings about MIOSIS - constricts the pupil
MYDRIASIS = dilation of the pupil is caused by the Diltor Pupillae
Is this statement true or false?
Ciliary processes are connections between the ciliary body and the crystalline lens
False - Ciliary processes secrete aqueous humour
It is the ciliary muscle that attaches the ciliary body and crystalline lens to bring about accommodation
Is this statement true or false?
The Uveal tract is made up of the iris, ciliary body and the choroid
True
Is this statement true or false?
Macular degeneration may occur due to dysfunction of the supra choroid
False - Macular degeneration may arise from dysfunction of Bruch’s membrane
Is this statement true or false?
The nucleus of the crystalline lens governs lens shape during accommodation
False - the LENS CAPSULE governs shape changes that occur during accommodation
The Nucleus is the oldest lens fibres
What is the ocular adnexa
Lacrimal apparatus, orbit, extra ocular muscles, eyelids, conjunctiva
