Imaging Science FundamentalsChester F. Carlson Center for Imaging Science The Human Visual System The Eye.

Slides:

Advertisements

Similar presentations

THE HUMAN EYE Gives the sense of sight. Allows us to learn more

Advertisements

Chapter 10 Light.

Eye- Structure and Refraction

Human Eye  A human eyeball is like a simple camera! Sclera: outer walls, hard, like a light-tight box. Cornea and crystalline lens (eyelens): the two.

Ranya Marrakchi Kelsey Wright Taylor Pakulla

Review – for marks! 1) What is the difference between a mirror an a lens? 2) Why do you think we have a lens in our eye instead of a mirror?

Photoreception - Vision. Eyelids (palpebrae) separated by the palpebral fissue Eyelashes Tarsal glands Lacrimal apparatus Vision Accessory structures.

Lenses  Lenses display focusing properties because of refraction.  A convex lens will focus a parallel beam of light to a certain point.  A concave.

Parts of the Eye - Pupil.

Eyes & Vision. Outermost layer of the Eye Cornea – ‘window’ – bulges slightly outward, allows light to enter – only truly transparent portion. Absence.

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science The Human Eye and Vision 1 (Producing The Image)

The Human Eye and Vision 2 (Processing The Image)

 Cornea: ◦ Tissue that forms a transparent, curved structure in front of the eye ◦ Refracts light before it enters the eye  Retina: ◦ A layer of cells.

The Human Eye and Vision The structure of the eye –Iris –Cornea –Lens Focusing –Cornea –Accommodation The Retina –Photoreceptors –Processing time –Sensitivity.

The Human Eye. The human eye is similar to a camera!! Light enters through an opening, is focused through a lens, passes through a light-tight (dark)

The Human Visual System The Eye. Anatomy of the Human Eye Cornea Pupil Iris Sclera Retina Optic Nerve Lens.

The Human Eye and Vision The structure of the eye –Iris –Cornea –Lens Focusing –Cornea –Accommodation The Retina –Photoreceptors –Processing time –Sensitivity.

12.3 Lens Technologies and the Human Eye

The Eye: Structure & Function

Senses- The Eye The human eye is the organ which gives us the sense of sight, allowing us to learn more about the surrounding world (environment) than.

Anatomy of the Eye Even though you can’t easily see it, the cornea is a very important structure in the outer avascular fibrous tunic – It’s composed of.

Human Perception of Light

The Eye and the Nervous System

Eye Notes You tube video below E1MvRmWg7I.

VISION the sense we rely on most often. Photoreceptors in the eye are sensitive to wavelengths of light energy called the visible spectrum.

Human Eye  A human eyeball is like a simple camera! Sclera: White part of the eye, outer walls, hard, like a light-tight box. Cornea and crystalline lens.

Unit 2 Notes: Vision Tuesday (1) Outer Layers of The Eye 3 layers surrounding inner fluid:3 layers surrounding inner fluid: –Outermost = Sclera.

Human Biology Sylvia S. Mader Michael Windelspecht

Cornea- The clear covering at the front of the eye that lets light rays into the eye.

The Eye. Cross-section of an eye muscle optic nerve aqueous humour lens pupil iris cornea ciliary muscle vitreous humour blind spot retina sclera.

Receptors Receptors are part of the co-ordination system that detect the changes of the environment by means of stimuli. Two types... Interoceptors – receptors.

Senses Vision. V I S I O N 70% of all receptors in the body are in the eye.

JP© 1 THE EYE JP© 2 sclera pupil iris JP© 3 cornea sclera choroid retina fovea vitreous humour aqueous humour blind spot optic nerve pupil iris.

The Eye and Sight Describe the relationship between the structure of the eye and sight Contrast ways in which light rays are bent by concave and convex.

SPECIAL SENSES. the human body is very sensitive to conditions in both its internal and external environment the nervous system collects information about.

The Human Eye 13.6 Optics THE HUMAN EYE: How Images Are Formed The human eye gathers light from objects. In a healthy eye, a smaller, inverted, real.

Lenses. Diverging and Converging Lenses Double Convex lenses focus light rays to a point on the opposite side of the lens. Double Concave lenses diverge.

The Human Eye. A convex lens is the type of lens found in your eye. The lens takes light rays spreading out from objects and focuses the light, through.

Chapter 9 - The eye $100 $200 $300 $400 $500 $100$100$100 $200 $300 $400 $500 Eye Anatomy Eye Physiology More Parts of the Eye Eye Problems More Vocab.

The Human Eye. In many ways, the human eye is similar to a camera. Light enters through an opening, is focused through a lens, passes through a light-tight.

The Physiology of Vision. Anatomy of the eye 1- sclera: is the outer protective layer. 2- cornea : anterior, modified part of the sclera, light rays enter.

Human Perception of Light

Special Senses The Eye.

Vision The Eye Contains photoreceptors Contains accessory organs including eyelids, lacrimal apparatus, and muscles.

Chapter 12 Review Light and Vision. Category: The Eye Give the name and function of the eye part indicated by #3 (the thin layer between #1 and #2). Choroid.

Sensory Physiology The Vision Accommodation Blind spot.

Section 12.1 (Part 1) The Human Eye.

THE EYE The eye is the receptor organ that is highly specialized to trap light and very sensitive to changes in the immediate surroundings. It is located.

Coordination and Response in Plants and Animals

Structure of Human Eye: –Eye Muscles, Optic nerve, sclerotic coat –Cornea, iris, pupil,, lens, retina, blind spot –aqueous humour, vitreous humour, ciliary.

Name them!! There are 5! Hearing Sight Touch Taste Smell.

Lens Applications.

The physics of vision The eye is essentially an opaque eyeball filled with a water-like fluid. In the front of the eyeball is a transparent opening known.

Eye Structure and Seeing Light. The eye is like a camera: Light enters, is focused on a surface, and a picture is made. Light enters your eye through.

Parts of the Eye. Cornea: protects the inner eye whilst letting light in Aqueous Humour: clear and colorless liquid that supports the shape of the cornea.

PL3020/FM2101/PL2033 Physiology Vision 1.

The Special Senses Vision (sight) Gustation (taste) Olfaction (smell) Hearing Equilibrium (balance) Chapter 17.

Ishihara test for color blindness

The Human Eye Extension.

The Human Eye and Vision

C-Notes: Anatomy of the EYE

The Eye and Sight Describe the relationship between the structure of the eye and sight Contrast ways in which light rays are bent by concave and convex.

Chapter 12 Review Light and Vision.

Presentation transcript:

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science The Human Visual System The Eye

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science In this section... u Anatomy of human eye u Image formation by human eye u Method of light detection u Retinal processing u Eye optical defects and diseases

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Human Visual System Image formation Exposure Control DetectionProcessing Cornea Lens Iris/pupil Photoreceptor sensitivity Retina Rods Cones Brain

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Human Eye u Human eye is a complete imaging system. Ear side (Temporal) Nose side (Nasal) Cornea Aqueous Humor Pupil Iris Ciliary Muscle Sclera Fovea Retina Optic Nerve Vitreous Humor Eyelens Choroid Suspensory ligament

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Image Formation u The curved surfaces of the eye focus the image onto the back surface of the eye. Object Image

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Cornea u The outer wall of the eye is formed by the hard, white sclera. u Cornea is the clear portion of the sclera. u 2/3 of the refraction takes place at the cornea. Sclera Cornea

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Iris and Pupil u Colored iris controls the size of the opening ( pupil ) where the light enters. u Pupil determines the amount of light, like the aperture of a camera. Iris Iris open Dilated pupil Iris closed Constricted pupil Pupil

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Lens u Eye lens is made of transparent fibers in a clear membrane. u Suspended by suspensory ligament. u Used as a fine focusing mechanism by the eye; provides 1/3 of eye’s total refracting power. u Non-uniform index of refraction. Lens Suspensory Ligament Ciliary muscle Transparent Fibers Cross section of the eye lens

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Accommodation u The suspensory ligaments attach the lens to the ciliary muscle. u When the muscle contracts, the lens bulges out in the back, decreasing its focal length. u The process by which the lens changes shape to focus is called accommodation. Relaxed muscle Taut ligaments Distant object Near object Contracted muscle Slack ligaments

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Aqueous Humor and Vitreous Humor u Transparent gelatinous liquid filling the eye. u Provides nutrients to the cornea and eye lens. u Also helps maintain the eyeball shape with its pressure. Vitreous Humor Aqueous Humor

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Retina u Retina is the photosensitive “detector” for the eye. u Two types of receptors in the retina: rods for low light level, and cones for color. u Located at the center of the retina, fovea contains a greater concentration of cones. u Signals from the receptors leave through the optic nerve to the brain. Retina Optic Nerve Fovea

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Plexiform Layer u The retina is made of three layers: u Plexiform layer is a network of nerves which carry the signals from the photo receptors. u Photo receptors. u Choroid provides nourishment to the receptors, as well as absorb any light that didn’t get absorbed by the photo receptors, like a antihalation backing in film. Fovea Plexiform Layer Photo receptors Choroid Optic Nerve Light

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Rods and Cones u Highly sensitive to low light level or scotopic conditions. u Black and white. u Dispersed in the periphery of the retina. Synaptic endings Cell nucleus Inner segments Outer segments Rod Cone u Sensitive to high light level or photopic conditions. u Three types of cones responsible for color vision. u Concentrated in the fovea.

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Adaptation u Why can’t you see immediately after you enter a movie theater from daylight? u The threshold of detection changes with overall light level. u The switch is quite gradual, until the sensitivities of cones and rods cross over at about 7 minutes in the dark. Photopic (cones) Scotopic (rods) Time in dark (minutes) Threshold of detection (log scale)

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Distribution of Photoreceptors u Cones are concentrated in the fovea. u Rods predominate the periphery. u There is a blind spot where there are no photoreceptors, at the point where the nerves exit the eye (optic nerve). 20 º 40 º 60 º 80 º 20 º 40 º 60 º 80º 0 º Angle 0 º 20 º 40 º 60 º 80 º 60 º 40 º 20 º Number of receptors per mm 2 Rods Cones Blind spot Visual Axis Nasal Temporal

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Human Vision u Human Cone Response to Color u three cone types (S,I,L) correspond to B,G,R Wavelength (nm) Relative response BlueCyanGreenRed 490 ILS

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Retina u The retina is made of network of nerve cells. u The network works together to reduce the amount of information in a process called lateral inhibition. To optic nerve Light Cones Rods Bipolar cells Amicrine cells Ganglion cells Horizontal cells

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Hermann Grid u Illustrates lateral inhibition.

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Hermann Grid u Point A looks darker because there are 4 inhibitory inputs u Point B looks lighter because there are only 2 inhibitory inputs A B

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Mach Bands Actual brightness Perceived by you

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Eye Defects u Image focuses on the retina for a normal eye. u Distant objects look blurry for a myopic (near sighted) eye. u Near objects look blurry for a hyperopic (far sighted) eye. Normal Myopic Hyperopic Object at infinity Eyes at relax state.

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Myopia - Near sightedness u Distant objects look blurry because the eye cannot relax any farther so that the image is focused before the retina. u Near object in focus without accommodation. u Corrected with a negative lens. Myopic eye relaxed Blurry Myopia corrected with a negative lens Far object The virtual image from the diverging lens appears to be closer. Near object Myopic eye relaxed In focus Far object

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Hyperopia - Far sightedness u Near objects look blurry because the eye cannot accommodate enough for near objects. u Far object in focus. u Corrected with a positive lens. Hyperopic eye Partially accommodated In focus Hyperopia corrected with a positive lens Far object Light from the converging lens looks as though it is coming from the distance. Hyperopic eye Fully accommodated Blurry Near object

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Contact Lens u Contact lens is an alternative to corrective lenses. u Changes the curvature of the cornea by adhering to the surface with some fluid. Cornea Contact lens Fluid

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Presbyopia - “Old eye” u Lens hardens with age. u Eye cannot adequately accommodate near objects. u Bifocals (lens with two focal lengths) contains a concave lens for distance (if needed) and a convex lens for near objects. Near objects magnified Far objects Concave for distance correction (if needed) Convex for near object correction

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Astigmatism u The cornea is not spherical; Focal length different from one plane to a perpendicular plane. F’ horizontal F’ Vertical Object Image at F’ Vertical Image at F’ Horizontal Cornea Direction of blur

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Astigmatism u Correction of astigmatism is done through the use of a cylindrical lens. u Cylindrical lens converge rays in one plane but not the perpendicular plane. Cylindrical lens Rays in the vertical plane are undeviated Rays in the horizontal plane are focused

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Common Eye Diseases u Cataract - Clouding of the lens. u Symptom: Loss of vision u Cure: Lens replacement u Glaucoma - Pressure buildup in the eye, damaging the retina. u Symptom: Loss of vision first in the periphery. u Cure: Surgery to drain fluid from the eye. u Loss of vision is usually permanent

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Common Eye Diseases u Detached retina - portion of the retina detaches from the back of the eye. u Symptom: Perception of flashes, Loss of vision u Cure: Laser surgery to reattach retina u Pink eye - Infection of the surface of the eye. u Symptom: Irritation u Cure: Antibiotics Ow!

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Your eye care Go see a doctor if you think there is something wrong with your eye- Early detection is essential to keeping damage low and preventing permanent loss of your vision.