Vision and Structure of the Eye

These flashcards cover essential vocabulary and concepts related to the anatomy of the eye, its structures, functions, and visual conditions.

What causes vision visual sensation?

It is caused by photons detected by visual receptors in the eye and modified by accessory structures.

What is the fibrous layer of the eye?

It is the outermost layer of the eye, providing protection and attachment for extra-ocular muscles.

What is the sclera?

The white outer coat of the eyeball, providing structure and protection.

What is the cornea?

A modified sclera adapted for transparency that focuses light.

What does avascular mean, especially in the context of the cornea?

It describes a type of tissue that does not contain blood vessels, as seen in the outer surface of the cornea.

What is the vascular layer (uvea) of the eye?

It is the middle layer of the eye that secretes and reabsorbs aqueous fluid.

What is the choroid?

Connective tissues supporting blood vessels and lymphatics for eye tissue.

What is the function of the iris?

It controls the amount of light entering the eye and determines eye color.

What is the pupil?

The hole in the center of the iris through which light enters the eye.

What is the pupillary sphincter and what is its function?

It is a ring of smooth muscle that decreases pupil diameter upon contraction.

What is the pupillary dilator?

It is a muscle that dilates the pupil by stretching the sphincter muscle.

What is the ciliary body and what does it do?

It produces aqueous fluid and controls focus by adjusting lens shape.

What is accommodation in the context of vision?

It is the change in the lens shape to focus on near or far objects.

What is presbyopia?

It is the loss of ability to accommodate due to stiffness of the lens with age.

What is the function of the epithelial layer of the ciliary body?

It secretes aqueous humor and connects the ciliary body to the lens.

What is aqueous humor?

It is a fluid that nourishes the cornea and lens, and maintains intraocular pressure.

What is glaucoma?

It is a condition caused by inadequate drainage of aqueous humor, leading to increased intraocular pressure.

What are ciliary processes?

They are folds in the epithelium connecting the ciliary body to the lens.

What are lens fibers?

They are convex layers of elongated cells filled with crystallin proteins that help focus light.

What are cataracts?

Clouding or discoloration of the lens, preventing clear vision.

What is the retina?

The inner layer of the eye containing photoreceptors that form images.

What is the function of the pigmented layer of the retina?

It absorbs excess light and separates the interior of the eye from the bloodstream.

What are photoreceptor cells?

They are cells in the retina that respond to light; includes rods and cones.

What are rods?

Photoreceptors that allow vision in low light conditions.

What are cones?

Photoreceptors responsible for color vision.

What is rhodopsin?

It is a light-sensitive membrane receptor protein found in rods.

What is retinal?

A derivative of Vitamin A that is activated by light in rhodopsin.

What are ganglion cells?

Neurons in the retina whose axons form the optic nerve.

What is the optic disc?

The point where the optic nerve exits the eye; contains no photoreceptors.

What is the macula?

An area of the retina with a high concentration of cones; responsible for sharp vision.

What is the fovea?

The central part of the macula that provides the highest visual acuity.

What is the visual axis or light pathway?

The path that light follows through the eye from the cornea to the retina.

What is the optic chiasm?

The point where optic nerves from each eye cross to the opposite side of the brain.

What is myopia?

Nearsightedness; difficulty seeing distant objects due to a longer eyeball.

What is hyperopia?

Farsightedness; difficulty seeing near objects due to a shorter eyeball.

What is colorblindness?

Inability to distinguish between certain colors; includes types such as deuteranopia and protanopia.

What is deuteranopia?

A type of colorblindness characterized by difficulty distinguishing between green and red, due to issues with green cone photoreceptors.

What is protanopia?

A type of colorblindness characterized by difficulty distinguishing between red and green, due to issues with red cone photoreceptors.