Visual Systems anatomy Flashcards
What structures make up the eye?
Upper eyelid Palpebral fissure Lateral canthus Lower eyelid Pupil Iris Sclera Medial canthus Caruncle Limbus (border between cornea and sclera)
What are the main featured of the lacrimal system?
Tears produced by lacrimal gland
Drain through the two puncta, openings on medial lid margin
Flow through superior and inferior canaliculi
Gather in tear sac
Exit tear sac through tear duct into nasal cavity
What is tear film?
Maintains smooth cornea-air surface
Oxygen supply to Cornea – normal cornea has no blood vessels
Removal of debris (tear film and blinking)
Bactericide
What are the three layers of tear film?
Lipid layer
Water layer
Mucin layer
What is the function of the lipid layer?
reduce tear film evaporation - produced by a row of Meibomian Glands along the lid margins
What is the function of the mucinous layer corneal surface?
maintains surface wetting
What is the conjuctiva?
Thin, transparent tissue that covers the outer surface of the eye
What is the extent of the conjuctiva?
It begins at the outer edge of the cornea, covers the visible part of the eye, and lines the inside of the eyelids
It is nourished by tiny blood vessels that are nearly invisible to the naked eye
What are the three layers of the coat of the eye?
Sclera - hard and opaque
Choroid - pigmented and vascular
Retina - neurosensory tissue
What is the sclera?
commonly known as “the white of the eye,”
the tough, opaque tissue that serves as the eye’s protective outer coat.
High water content
What is the cornea?
The transparent, dome-shaped window covering the front of the eye.
Low water content
What is the function of the cornea?
Powerful refracting surface, providing 2/3 of the eye’s focusing power. Like the crystal on a watch, it gives us a clear window to look through
What are the 5 layers of the cornea?
1 – Epithelium
2 – Bowman’s membrane
3 – Stroma – its regularity contributes towards transparency
4- Descemet’s membrane
5- Endothelium – pumps fluid out of corneal and prevents corneal oedema, glucose supply
What happens if you hydrate the cornea?
Becomes white
What is the Uvea?
Vascular coat of eyeball and lies between the sclera and retina.
What are the three parts of the uvea?
iris, ciliary body and choroid
Intimately connected and a disease of one part also affects the other portions though not necessarily to the same degree.
What is the choroid?
lies between the retina and sclera. It is composed of layers of blood vessels that nourish the back of the eye.
What is the iris?
Controls light levels inside the eye similar to the aperture on a camera.
Controls light levels inside the eye similar to the aperture on a camera.