Ch- 6 pg. 182-184 half pg

Anterior Chamber

Between cornea and iris

Posterior Chamber

Between the iris and lens

Aqueous humor

Both chambers are filled with fluid substance anterior and posterior

What material fills the eyeball between the lens and the retina?

Transparent jelly-like material know vitreous humor

Conjunctiva

Membrane lines the eyelid and covers the front of the eye except the cornea

What does the term “visual acuity” refer to?

Acuteness or sharpness of vision.

What are the most common causes of defects in visual acuity?

Errors of refraction

Refraction

Ability of the eye to bend parallel light rays coming into so they can be focused on the retina

Error of refraction

Light rays are not being refracted or bent properly and are not adequately focused on the retina

Myopia

Nearsighted condition, difficulty seeing objects at a distance

Myopia side effects

Squinting and Headaches result eyestrain

What specific symptoms might someone with hyperopia experience during close tasks?

Difficulty viewing objects at a reading or working distance, blurring, headaches, and eyestrain

What is astigmatism and how does it affect vision?

Distorted and blurred vision for both near and far objects. Corrected with Corrective lenses

What is Presbyopia and what physiological change causes it?

Decrease ability to focus clearly on close objects.

At what age does presbyopia typically begin to occue

After age 40

Ophthalmologist

Physician specializes, diagnosing, and treating diseases and disorders of the eye, qualified to prescribe medications and perform eye surgery

Optometrist

Licensed primarily health care provider expertise measuring visual acuity and prescribing corrective lenses for treatment of refractive errors. NOT A PHYSICIAN

Optician

Professional interprets and fills prescriptions for eyeglasses and contact lenses

What test is commonly used in combination with other tests to diagnose myopia?

Distance Visual Acuity (DVA) test

Which eye chart is most frequently used in medical offices to test distance visual acuity?

Snellen eye chart

What does the Snellen chart for school-age children and adults consist of?

A chart of letters in decreasing sizes

Who is the Snellen “Big E” chart designed for, and how is it structured?

Designed for preschool children, non english speaking, and non readers. Capital letter E in decreasing sizes and arranged in different directions

Why are visual acuity charts with pictures of familiar objects considered less accurate accurate than Snellen charts?

Some children cannot identify the objects due to a lack of recognition after than an actual defect in their visual acuity

Which chart is specifically recommended for testing the vision of preschool children?

Snellen Big E chart

Where should a Snellen Test be performed?

Well-lit room free of distractions

What is the standard testing distance for a Snellen test?

20 ft

How can a clinic efficiently maintain the proper distance mark?

Marking it off with paint or tape so it does not require remeasuring every time

What do the two numbers separated by a line on the chart represent?

Visual acuity fraction showing the testing distance over the normal visual distance

What does the numerator (the number above the line) represent?

Distance (in feet) at which the test is conducted, usually 20 feet

What does the denominator (the number below the line) represent?

The distance from which a person with normal visual acuity can read at the line

What does a 20/20 reading indicate?

Normal Distance Visual Acuity (DVA)

What does 20/30 reading mean?

The patient reads at 20 feet what a person with normal acuity can read at 30 feet

What does a 20/15 reading mean?

Above average acuity, patient reads at 20 feet what a normal person can only ready at 15 feet

What is a person with normal visual acuity able to do?

See clearly and distinguish fine details close up and at some distance

In medical terms, what does “refraction” mean regarding the eye?

Ability of the eye to bend parallel light rays coming into it so they focus directly on the retina

What physically happens during an error of refraction?

Light rays are not being refracted (bent) properly, meaning not focus on the retina

How does the physical shape of the eyeball change in a person with myopia?

Eyeball too long from front to back

Where do light rays focus in a myopic eye?

Focus in front of the retina

What are the treatment options to correct myopia?

Corrective lenses (eyeglasses, contact lenses) or laser eye surgery

How does the physical shape of the eyeball change in a person with hyperopia?

Eyeball is too short from front to back

Where do light rays focus in a hyperopic eye?

Behind the retina

How does a cornea with astigmatism differ from a normal cornea?

Normal cornea round, spherical, and smooth. Astigmatic cornea is oval shape

Why does an oval cornea cause distorted vision?

Causes light rays to focus on two different points on the retina instead of one

What is the primary function of the vitreous humor?

Maintain the shape of the eyeball

Why does the white sclera show through the conjunctiva?

Conjunctive covering the sclera is transparent containing only a few capillaries