Flashcards in Eyes Deck (89)
What is the translation of ‘humor’ with regards to the eye?
Chamber (aqueous and vitreous)
What is the name for the gap between the cornea and the sclera?
How does vit A deficiency affect the eye?
Less vit A = Less rhodopsin protein = Night blindness
What is ptosis?
Drooping of upper eyelid
In the context of optics what is an aberration?
Failure of rays to converge on one focus
Which thalamic nucleus is involved in the visual system?
Lateral geniculate (LGN)
How does laser eye surgery work?
Burns surface of cornea to change it's shape
What is another name for eyelids? Where are the two eyelids connected and what fissue seperates them?
Connected at med and lat canthus
Separated by palpebral fissure
What glands run along the inner margin of the eyelids and what is their function?
Tarsal glands- Secrete lipid rich product to stop eyelids sticking together
What is the lacrimal caruncle?
At the medical cunthus, it secretes gritty deposits which sometimes appear on your eyes in a morning
Which muscle closes the eyelids?
Orbicularis oculi (deep to thin layer of skin)
Which muscle raises the upper eyelid?
Levator palpebrae superioris
What is the conjunctiva?
The epithelium (stratified squamous) which covers the inner surface of the eyelids (palebral conjunctiva). The ocular conjunctiva also covers the ant surface of the eye
What is the cornea made of and what is it's function?
5-7 cells layer of stratified squamous epithelium
It is 2/3 of the eyes total optical power as its curvature reflects light). It has a power of about 43 diopters
What is the function of the lacrimal apparatus?
Produces, distributes and removes tears
What is the fornix?
The pocket created where the palpebral and ocular conjunctiva meet. The superiolateral fornix contains the ducts from the lacrimal gland, which provides tears and nutrient/ o2 demands for the cells of the cornea
What antibacterial agent is in tears?
Lysozyme (antibacterial enzyme)
How are tears removed?
Blinking sweeps them to medial canthus (area known as lacrimal lake) > lacrimal caruncle > lacrimal puncta (two small pores) > lacrimal canaliculi > lacrimal sac >nasolacrimal duct > inferior meatus > nasal cavity
What is the choroid?
Contains a network of BV's to nourish retina and other eye cells, pigmented black in humans
What is the macula lutea?
Oval shaped, v.yellow pigmented 6mm spot which contains the perifovea which circumscribes the parafovea which circumscribes the fovea (largest cone conc, used for high resolution central vision)
What is the difference between the aqueous humour and the vitreous humour?
Aqueous= Like water, continually replaced
Vitreous= Stagnant gel, produced by secretions of ciliary bodies in vitro. Provides pressure to keep everything in place
What are the ciliary bodies?
Ciliary muscles + ciliary processes
(Produces aqueous humour and vitreous when in vivo)
What are the ciliary processes?
Inward folds of the choroid between the suspensory ligaments
What is the sclera?
Tough fibrous coating which provides attachments for muscles
What kind of proteins are rhodopsin and photopsin?
G-protein coupled receptors
What are the different proteins in rods and cones?
Why is vitamin A important for sight?
Both rhodopsin and photopsin use conversion of retinol (11-cis to 11-trans) to activate cascades
Retinol is a slightly processed version of vitamin A
In a dark environment what is the pathway between the rod cell and the ganglion cell?
Rod cell fires (glutamate) which inhibits the bipolar cell so therefore the BP cell does not excite the ganglion cell and the ganglion cell does not fire
What is the visual pathway from rod cell to visual cortex?
Rod > bipolar > ganglion > LGN > primary visual cortex