Refractive Errors Flashcards
What is the lens
A clear part of the eye behind the iris that helps to focus light, or an image, on the retina
What is the cornea
The clear outer part of the eyes focusing system located at the front of the eye
What is the pupil
The opening at the center of the iris
What is the iris
The colored part of the eye that regulates that amount fo light entering the eye
What is the fovea
The center of the macula and gives the sharpest vision
What is the retina
The light sensitive tissue lignin and the back of the eye
What is the optic nerve
A more bundle of ore than one million nerve fibers that carries visual messages from the retina to the brain
What is the macula
The smallest area of the retina that gives central vision
What is vitreous gel
A clear gel that fils that inside of the eye
What is refraction
Deflection of light
How does a healthy eye refract light
- Bends (refracts) light in order to focus it on the retina
What can impede light from focusing directly on the retina
The shape of the eye
What is the most common cause of change in visual acuity
Emmetropia
*healthy state (light focuses directly on retina)
Hyperopia
*far-sightedness (light focuses behind retina)
Myopia
*near-sightedness (light focuses in front of retina)
What is presbyopia
Natural loss of accommodations with age
1. Happens around 45 y/o
2. Cannot maintain focus on close objects
What is astigmatism
Diffuse spread of light (not sharply focused on retina)
1. Corrected with contact lenses or surgery
