Light & Vision - Martin Flashcards
Accommodation
Lens gets more curved/rounded –> more refraction
Spherical aberration
The peripheral of the lens is flatter, resulting in light being refracted more than in the center
Chromatic aberration
Different wavelengths are refracted differently
Emmetropia
Normal visual acuity
Anisometropia
One eye is different from the other
Myopia
- Near-sighted
- Eyeball is too long
- Corrected w/biconcave lens
Hypermetropia
- Far-sighted
- Eyeball is too short
- Corrected w/biconvex lens
Presbyopia
Loss of accommodation with age
What are some causes of diplopia?
Astigmatism
Strabismus: abnormal alignment of eyes
Amblyopia: uncorrectable loss of vision in one or both eyes
Rhodopsin
- Converts cis to trans-retinal leading to action potential in ganglion cell
- Post transduction: Na+ channel can’t remain open w/o cGMP
- Dark: depolarization (Na+ influx, K+ efflux)
- Light: hyperpolarization (reduced Na+ influx, K+ efflux)
What is the difference between on-center and off-center ganglion cells?
On center cells send impulses when light strikes the center of the field, off center cells send impulses when light strikes the periphery of the field
Which pathway permits visual stimuli to be associated w/language, color and form?
Ventral stream/pathway
Which pathway processes the form and motion of the stimulus?
Dorsal stream/pathway
What is retinitis pigmentosa?
Normal removal and scavenging of retinal receptor membrane sheets or discs is impaired leading to less light arriving on the retina
What does the Young-Helmholtz theory postulate?
3 kinds of color reporting elements exist in the visual system (cones)
What does Hering’s Opponent Process theory postulate?
Color vision postulated by 2 color elements (red & green reporting elements and blue & yellow reporting elements)
Which color vision theory is accurate?
Both! Young-Helmholtz explains how retinal cones process information while Hering explains how rental P cells and LGN cells process information
Which pigments are coded on the X-chromosome? Chromosome 7?
X: green and red sensitive
7: blue
Which cones are absent from the fovea?
Blue cones
Deuteranomaly
Defect in the middle wavelength sensitive pigment (green sensitive); still a trichromat
Deuteraopia
Absence of green sensitive cone; results in dichromatism
