1. Eye-spots
Bipolar cell
Epithelial invaginated eye
Octopus

2. compound eye
Fish

4. Anatomy of Eye
Eye vs. Camera cornea lens iris iris lens lens sclera box retina film brain DP&E

5. Orbit

6. Anatomy

7. Anatomy

8. Anterior Chamber

9. Refractive system Cornea Aqueous Humor Pupil Lens Vitreous Humor
Refractive surface
1st: cornea - refracts light the most (about 80% - 43D)
2nd: anterior surface of the lens
3rd: posterior surface of the lens

10. Focusing for Close Vision
Accommodation
contraction of the ciliary muscles releases tension in the suspensory ligaments and allows the lens to elastically recoil and bulge out on both of its sides

11. Focusing for Close Vision
Pupillary Constriction
contraction of the circular muscles of the iris causes the pupil to constrict, reducing the amount of light entering the eye, increasing the clarity of the image

13. Pupil

15. Focusing for Close Vision
Convergence
medial rotation of the eyeballs by the medial rectus muscles directs the eyeballs toward the object being viewed

16. Cornea Cornea covers the anterior portion of the eyeball (1/6th)
transparent, avascular, allowing light to enter the eye
Only tissue of the body that does not risk rejection by the recipient when transplanted from one person to another
The cornea is supplied with many pain receptors (nerve endings)

17. Lens avascular, transparent, biconvex, flexible
always increasing in size with age as new fibers are added to it so that it becomes denser and less elastic, and more convex so that it becomes less able to focus light properly

18. Retina Pigment epithelium(RPE): supporter Layer of photoreceptor cells
photopigment regeneration, blood supply
dark with melanin, decreasing light scatter
Layer of photoreceptor cells
outer segments and inner segments of rod /cone
Outer limiting membrane
Outer Nuclear Layer (ONL)
cell bodies of rods & cones
Outer Plexiform Layer (OPL)
rod and cone axons/ horizontal cell dendrites/ bipolar dendrites
Inner Nuclear Layer (INL)
Nuclei of horizontal, bipolar and amacrine cells
Inner Plexiform Layer (IPL)
axons of bipolars (and amacrines)/ dendrites of ganglion cells
Layer of Ganglion cells (GCL)
nuclei of the ganglion cells / displaced amacrine cells
Layer of optic nerve fibers
fibers from ganglion cells traversing the retina to leave the eyeball at the optic disc
Internal limiting membrane

19. Major diseases and treatment
artificial cornea ?
disease; corneal burn, scar, perforation, etc
penetrating keratoplasty (PKP), keratoprosthesis, cultured cornea
artificial iris ?
disease; iniridia, iridodialysis, etc
iris contact lens, iris IOL
artificial lens ?
disease; cataract, aphakia, etc
various intraocular lens (IOL)
artificial retina ?
retinitis pigmentosa (RP); 1/4000 in normal population
age-related macular degeneration (AMD); 1/20 in over 65

22. Normal Vision viewing angle: 140 degree resolution: 1 arcmin
photoreceptor : ganglion cell = 1:1(fovea) to 300:1(periphery)
intensity shift by a factor of 108
spectroscopy by 3 different pigments
rapid change and edge detector
spatial depth difference by binocular vision

23. Visual pathway Sensory neuron; photoreceptor 1st order; bipolar cell
Cone; color discrimination
Rod; scotopic vision
1st order; bipolar cell
2nd order; ganglion cell
Interneurons
horizontal cell
amacrine cell

24. Cone and Rod

25. Contrast Information Convergence and Receptive Fields
individual receptors do not have private lines up to the visual cortex
multiple receptors converge onto single higher order neurons on their way to the higher visual centers
Border information
begins within the retina itself
result of specialized arrangements of interneurons into center -surround ganglion cell receptive fields

26. Center-Surround Receptive Field
Bipolar cells(BC)
center of the receptive field
receive input from the photoreceptors
feed excitatory input onto GC
peripheral regions of the receptive field
feel excitatory information onto inhibitory cells
pass the inhibitory information to GC
Ganglion cell(GC)
"on-center, off-surround“: center is illuminated exclusively
a large amount of stimulation to GC, and no inhibition
“on-center, on-surround”: whole field were stimulated
peripheral inhibitory influences would come into play

27. Interaction with brain
Visual field; split in half and cross over
Optic nerve  LGN  primary visual(striate) cortex
Self-organization of the cortex: learning, organizing, testing
Artificial Neural Network: associative memory, task assignment problem, back propagation
Various "household chores" associated with vision
saccadic motion and compensation for it
the control of lens opening (pupillary reflex)
distance accommodation
binocular convergence

28. Visual pathway
Course of axons of 2nd order neurons; Optic nerve - optic chiasm - optic tract
3rd order; lateral geniculate body (LGN)
Course of axons of 3rd order neurons; geniculocalcarine tract (optic radiation)
Visual cortex (area 17) Visual association area cortex (area 18,19)

33. Visual Cortex Brain Crossover 4 layers
built-in memory + learned memory
recognition of pattern
moving object; hop the split gap in hemispheres
Crossover
crossover by lens + crossover by optic nerve: left half of an object in left hemisphere
match the crossover of the eye lenses
afferent; R-body  L-hemisphere
efferent; L-hemisphere  R-body
4 layers
complex(C), simple(S), geniculate(G)
separation into R & L layers
"ocular dominance”
repeat in every millimeter
repeat in front-to-back direction
50,000 neurons/mm3  600,000 neurons/12mm3

34. Visual Cortex Surface area of visual cortex
105neurons/mm2  150x106neurons/15cm2
mainly in fovea; 150,000cones  1000neurons/cone
Processing in primary visual cortex
mainly orientation response: direction of edge and line of visual images
fires when edge of particular orientation enters
all possible orientation; short line(9 neurons long)
Dissection and reconstruction of visual image
face recognition
dissection of smaller pieces of eyes, ears,nose
see eyes, ears,nose  complete face  grandmother
all in a fraction of second

36. Vision prosthesis
Enhanced vision: process image for maximum visibility & present information to still viable retina
Prosthetic vision: presents processed visual information to the inner retina or visual pathways
Artificial vision: process & interpret visual information & presents the result through another sensory modality