the_human_eye_day_18.ppt

8/17/2019 the_human_eye_day_18.ppt

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The HumanEye


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The Human Eye

Refractive index of lens

different for each

wavelength (colour)

Cool colours (blues)

appear closer; warm

colours (reds) further

away

Agree?


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Most people see the red,

Closer than the blue.Others see the opposite.

How about you?


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The Human Eye

Your eyes are about to get a worout! "ave

you stretched your eye muscles yet?

#o? $hen do that now%


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Are you seeing spots?


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Look at the cross for 10 seconds. What

do you see?


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Are these lines

bent&!?


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&or straight?


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What shapes do you see?


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Reading What is wrong withwith this sentence?

Aoccdrnig to rscheearch at Cmabrigde

Uinervtisy, it deosn't mttaer in waht oredr the

ltteers in a wrod are, the olny iprmoetnt tihng istaht the frist and lsat ltteer be at the rghit pclae.

The rset can be a toatl mses and you can sitll

raed it wouthit a porbelm. Tihs is bcuseae thehuamn mnid deos not raed ervey lteter by istlef,

but the wrod as a wlohe.


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Do you see the rait or theduck?


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Read This !ut Loud.


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Are "ou #ure? Read again.


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The Human Eye


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#tructure $ %unction

'R' coloured part of eye

controls light entering

*'+ blac hole in iris

where light enters


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C+,RA whites of the eye supports eyeball provides attachment

for muscles

+,#

converging lens allows us to see

ob-ects near and far


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C.R#,A transparent bulge over

pupil focuses light (refracts)

onto retina

R,$'#A internal membrane contain light/receptive

cells (rods 0 cones) converts light to electrical

signal


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&'ind #pot

.n retina where optic

nerve leads bac into

the brain

#o rod or cone cells .ther eye

compensates for this

area

$ry this test to proveyou have a blind spot&


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('ose 'eft eye and approachscreen )hi'e staring at the

'etters*)atch the dot+


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.$'C #,R1,

$ransmits electrical

impulses from retina to

the brain Creates blind spot

2rain taes inverted

image and flips it so we

can see


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R.3 456 million cells

detect brightness

(blac 0 white)

for night vision C.#,

7 million cells

detect colour (R82)

8A#8+'.# C,++ 3etect movement and

patterns


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,orma' Eye %ocus

92lind spot:


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-ideo

You$ube

9$he "uman ,ye: and 9"ow the "uman ,ye

ors:


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%ocusing ro'ems

"Y,R.'A


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%ar/#ighted Hyperopia


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%ocusing ro'ems

R,2Y.'A


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%ocusing ro'ems

=Y.'A

#ear/sightedness

roblem seeing ob-ects

far away 3istance between lens

and retina too large

+ight focused in front of

retina Correct with diverging

lenses


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,ear/#ighted 2yopia


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Diseases of the Eye

A$'8=A$'=

,ye cannot focus an

ob-ect>s image on a

single point on retina Cornea is oval instead

of spherical

Causes blurred vision

ome types can becorrected with lenses


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Diseases of the Eye

8+A*C.=A

8roup of diseases

Affects optic nerve /

pressure +oss of ganglion cells

8radual loss of sight

and eventual blindness

Chec eyes regularly

Can be treated


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Diseases of the Eye

CA$ARAC$

Clouding forms in lens

due to denaturing of

lens protein

.bstructs passage oflight

Caused by age chronic

exposure to *1 or due

to trauma Removed by surgery


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-ision (orrection

C.#$AC$ +,#,

Artificial lens placed

over cornea

ame as glasses Corrects for both near

and far/sightedness

Also used for cosmetic

purposes (eye colour"ollywood)


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-ision (orrection

+A'@

9+aser Assisted 'n itu

@eratomileusis:

Refractive surgeryusing laser

Corrects near and far/

sightedness and

astigmatisms

the_human_eye_day_18.ppt

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