Light and the eye

yippeee

What two sub organs help to form images of distal objects on the retina?

What two sub organs help to form images of distal objects on the retina?

The lens and the cornea

What organ does 80% of the focusing for the eye?

The cornea

What organ does 20% of the focusing for the eye?

The

What is the name of the muscles that stretch the lens to help it focus on objects?

Cilliary muscles

What is the term given to the process of focusing light onto the retina using the lens?

Accommodation

What is given to the optical issue that fails to accommodate distant objects?

Optical Myopia

What are the two main causes of optical myopia?

Lens is too thick and the eyeball is too long (axial myopia)

What is the term given to the point where the eye can no longer adjust for objects at a specific distance?

The near point

What is the optical problem characterized by the lengthening of the near point?

Presbyopia

What is the optical problem characterized by the inability to accommodate near objects?

Hyperopia

What is the part of the retina where all high fidelity elements of an image are processed?

The Fovea

What are two main receptors found in the retina?

Rods and Cones

What is the name of the molecule that transduces light information into a neurological signal

Opsin

What is the name of the chemical process that allows opsin to communicate light information?

Isomerism

What is the only type of receptor found in the fovea?

Cones

Which type of receptor is found more commonly in the wider retina?

Rods

What type of vision do cones specify in?

daytime spatial and colour vision

What type of vision do rods specify in?

Light sensitivity

When measuring dark adaptation what must you do to make sure that the experiment only records light sensitivity?

place the light source away from the fixation point on the mask

Outline the two stages of dark adaptation?

increase in sensitivity for 3-4 minutes, 7-10 minute plateau, increase for 20-30 minutes

Which receptor is associated with the first stage of dark adaptation?

Cones

Which receptor is associated with the second stage of dark adaptation?

Rods

Which receptor is has a better sensitivity to light in dark environments?

Rods

How many times are rods better than cones when it comes to light sensitivity?

100,000x

What is the neural process of light information from photo-receptor to brain?

Photo-receptor, Bipolar cell, Ganglion cell, optic nerve and then brain

In the outer retina what is the convergence ratio of rod receptors to ganglion cells?

120:1

In the outer retina what is the convergence ratio of cone receptors to ganglion cells?

6:1

In the fovea what is the convergence ratio of cone receptors to ganglion cells?

1:1

What is the 1:1 convergence ratio most efficient at when it comes to light information?

Spatial resolution

What is the many:1 convergence ratio most efficient at when it comes to light information?

Spatial Summation (sensitivity)