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Optics of Vision Light refraction
Optics of Vision
Light refraction
Optics of Vision
Optics of Vision
Refraction power a lens “Diopter” = 1 m / focal length
Optics of Vision
Optics of Vision
Picture Formation
cataracts (opacities in the lens)
Picture Formation
• Lens accommodation
• Pupil adjustment
• Fusion of the two eyes
Optics of Vision
Optics of Vision
Accommodation
Accommodation
Accommodation
Vision problemsAmetropia : refraction error, inabiulity of properly focusing light on the retina, a frequent reason for reduced visual acuity
Vision problems
Accommodation
Presbyopia: Loss of accommodation by the lens
Vision problemsAstigmatism : irregular curvature of either the cornea or the lens, which lead to blurred or distorted vision due to parts of the image are out of focus.
Accommodation and parasympathetic
Pupillary Adjustment
Pupillary Adjustment
Visual acuity
Normally , people has the ability to distinguish contours that are approximately 1.75 mm apart at 6 meters distance from the eye
Visual acuity
Normally , people has the ability to distinguish contours that are approximately 1.75 mm apart at 6 meters distance from the eye
Photoreceptors
Cones
Rods
Color Blindness
Color Blindness
Red-green color blindness
Color Blindness
Red-green color blindness X linked
Color Blindness Red-green color blindness
X linked Deuteranope >>> green Protanope >>> red
Tritanopia >>> Blue Chromosome 7
***anomaly : shift in the spectrum of one of the proteins i.e. Deuteranomaly, Protanomaly, Tritanopia
Color Blindness
Tritanopia
Protanopia
Deuteranopia
Color Blindness
Tritanopia
Protanopia
Deuteranopia
Color Blindness
Tritanopia
Protanopia
Deuteranopia
Color Blindness
Color Blindness
Type Problematic colors
Deuteran (green)
Green/red, green/blue, green/gray, green/brown, blue/purple, orange/red, yellow/orange.
Protan (red)
purple/dark blue, orange/green, brown/dark green, red/brown, green/yellow, gray/purple
Tritan (blue)
blue/yellow, violet/yellow-green, red/red-purple, dark blue/black, yellow/white
Color Blindness
Type Prevalence
Deuteranomaly (green) 4.63%
Deuteranopia (green) 1.27%
Protanomaly (red) 1.08%
Protanopia (red) 1.01%
Tritanomaly (blue) 0.02%
Tritanopia (blue) 0.03%
Color Test Chart
74 VS 21
Color Test Chart
42 VS 4 “green” / 2 “red”
In conclusion
The colorblind have a narrowed color perception. Green is still green and red stays red most of the time, but not as vibrant or bright as a non colorblind would see it. Colors lie closer to each other, especially shades of colors.
VISUAL PATHWAY
The retinohypothalamic pathway• day/night cycle• Melanopsin ganglionic cells
Visual Pathways
The optic nerve has two principle branches
Right hemisphere
Hemi - anopia
Right hemisphere
Quadrant - anopia
Light Adaptation
Pupillary size
Pupillary LightReflex
Olivary pretectal nucleus
Edinger-Westphal nucleus
Edinger-Westphal nucleus
Light Adaptation
Pupillary size
Neural adaptation
Photoreceptor adaptation
Light Adaptation Pupillary size Neural adaptation Photoreceptor adaptation
Night blindness
Retinitis pigmentosa
Ganglionic Cells Subtypes
XY
XY
Position Receptive field Details movement
XY
Position Receptive field Details movement
W
Primary visual cortex
Lateral geniculate nucleus
Lateral geniculate nucleus
Lateral geniculate nucleus
Lateral geniculate nucleus
Lateral geniculate nucleus
Parvocellular systemMagnocellular system
