The Visual System Flashcards
What is the retina?
The retina is actually one of the last places where the light shines –the light passes through other parts of the eye first. The conversion of light into electrochemical signals happens here.
What is the cornea?
The cornea is the front, transparent layer of the eye. This part is usually shaved down during LASIK SURGERY.
What occurs in the cornea?
Refraction (bending/focusing)
What is the iris?
The colored part of the eye
What is the pupil?
The little hole where the light enters the eye. It can dilate and let in the right amount of light.
What happens in bright lights vs. low and dim lights?
Bright lights : the iris becomes the size of the pupil
Dim lights : the iris relaxes and pupil expands
What happens after the light enters the eye?
The light passes through the crystalline lens, a structure with many layers behind the cornea. This works to further refract the light to focus the image on the retina.
What is the lens?
The lens is dynamic and flexible because it changes shape to focus on different parts of the visual field. There are special muscles that help it be flexible.
What does aging do to the lens?
The lens flexibility reduces with age. This causes a form of farsightedness.
How does farsightedness occur?
This is caused because the lens isn’t flexible or the eyeball is shaped so that the distance between the cornea and the retina is too short. The image falls behind the retina.
How does myopia (nearsightedness) occur?
This is because the eyeball is shaped so that the distance between the cornea and the retina is too long. The image falls in front of the retina.
What can fix myopia and/or farsightedness?
Glasses, corrective lenses, or LASIK surgery which can change the curve of the cornea to bend the light so the image falls exactly on the retina.
What is the retina?
This is a many layered sheet of neurons that converts light in the back of the eye.
Describe the process for the light to get to the back of the retina.
The light must first go through this sticky, thick liquid and around the first layers of the retina to get to the photoreceptors.
What are photoreceptors?
They recieve and convert light.