Vision I+II Flashcards
What are the 4 stages of vision?
Light collection by eye, transduction b photreceptor, info proecessing by retina and visual cortex.
What are the advantages (2) for compound eye? How about refractive eye?
Compound eyes have ebtter sensitivity to mevement and detects wider range of waevlengths (polarized light); Refractive eye is optimized resolving power (acuity).
What does ommatidia mean?
the single unit of a compound eye. Increase visual acuity.
Name the three layers of the eye.
Outer layer: sclera (same layer of the cornea; sclera:white); coroid layer (blood vessel, pigmented layer); innermost: neural retina (photoreceptor and neurons)
What is the major refractory part of the eye?
Cornea
What is the adjustable refractory part of the eye?
Lens
If going under water, which part of eye is equivalent to not being functional?
Cornea
What is the borders for the anterior chamber? Is it fluid-filled or not?
Between cornea and iris; yes, aqueous humor.
Where is the aqueous humor produced?
by ciliary epithelium, which is dorsal to the iris. It is continuously produced; in order to reach the anterior chamber, it leaves the trabecular meshwork. Absorption is at canal of schlemm.
What if the anterior chamber fluid is over produced or not properly drained?
pressure building up leads to Glaucoma: result in blockage of blood flow into retina and damage to the neural retina. Second leading cause of blindness.
Define the concept of “accommodation”
Change in the refractive power of the lens due to changes in its shape. For far vision, the ciliary muscle is relaxed, suspensory ligament taut, and lens flattened.
Describe the accommodation process for seeing near object.
Ciliary muscle contracted, suspensory ligament relexed, lens thickened and focused.
How does age has to do with accommodation
lens becomes less elastic with aging
What happened with myopia/nearsighted? What lens to use?
focal plane is in front of the retina; too much refractive power (concentrate too quickly); correction is concave lens (refract the light a bit).
How about farsighted/hyperopia?
the focal plane falls behind the retina; use the convex lens to focus the light
What are cataracts?
Opacities in the lens of the eye that interfere with vision and can result in loss of parts of the visual field. Often developed with aging. The crystallins protein, which is filled inside the lens fiber cells, becomes sort of old and denatured.
What is fovea?
The point where majority of the light will hit in retina with fewest neuron cells. Light can travel directly hit the photoreceptor, detecting the light. Fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for reading, driving, and any activity where visual detail is of primary importance.
