The eye- functional anatomy

what is the choroid

• the choroid behind the retina which is pigmented & highly vascular

• , it provides blood supply of outer layer of retina

what is the optic disc

• the optic disc is when all the axons from the retina go out of the eye & for an optic nerve which takes in visual information to the brain

• it is also the blood vessels entry point and exit point

what is the fovea

• the fovea is when light comes into the eye, it focuses directly to the fovea as it has the highest visual acuity

what is the vitreous humor

it absorbs energy and protects the delicate structures of the eye, helping maintain its shape and providing cushioning especially the retina

what is a ciliary body

• a ciliary body secretes aqueous humour which flow in front of the lens & drains into the canal of shclemn

what is the iris

• iris is a smooth muscle that contracts & relaxes in order for the pupil to dilate & constrict in response to light levels

• it is the coloured part of the eye

what are lens

• it is a transparent organ which allows light through & helps focus on the retina

• they are held in place by suspensory ligaments which attach lens to the ciliary body which produces aqueous humor & contains smooth muscle

what is aqueous humor

• its provides nutrients & oxygen & also allows for maintaining pressure in the eye which keeps it inflates

what is cornea

• it is a transparent window which is involved in the refraction of light as it enters the eye

what is conjuctiva

• it is a thin membrane which covers the front of the eye & is involved in protecting of the eye & the tear fluid sit on front of the conjunctiva which protects the outer surface

what is the pupil

• is the opening in the center of the iris that regulates the amount of light entering the eye.

what is sclera

• is the white outer layer of the eyeball, providing structure and protection. It also serves as an attachment for the eye muscles.

what type of 2 muscles are the iris made of

1. circular muscle

2. radial muscle

describe the 2 muscle of the iris in controlling pupil size

• the circular muscle is parasympathetic and constricts the pupil when exposed to light, while the radial muscle is sympathetic and dilates the pupil as the fibre get shorter when exposed to darkness

what is the cornea

cornea allows the greatest degree of fraction, the lens are important for refocusing as it needs to be smooth in order for refraction to occur

what is asitgmatism

• a refractive error causing blurred vision due to an irregular shape of the cornea or lens.

what is LASIK

A laser correction surgery which changes the degree of curvature of the cornea

what is far vision

• the ciliary muscle is relaxed & lens is pulled taut (flat & thin) by intraocular pressure

what is near vison

• it is the ciliary muscle contracted & the lens has a curvature (which is round as it not under tension)

• contraction of the ciliary muscle is mediated by the parasympathrtic

what is presbyopia

• when the lens lose its flexibility , so is no longer able to become rounded , so not possible to focus on near object

• occurs with age

what is shortsightedness ’ (myopia)

• eyeball is too long

• parallel light is focussed in front of retina

what is longsightedness (hyperopia)

• when the eyeball is too short

• so near objects are brought to a focus behind the retina