Visual Acuity Study Guide

Ophthalmology → Study of the eye and diseases affecting the eye

Optomologist

• Medical school, residency, surgery

Optometrist → OD/Vision correction

• Does not go to medical school, but has education on the eye (not medical doctor or perform surgery)

• Diagnose and treat refractive disorders (treatment: glasses or contact lenses)

Optician → Certified/glasses

• The one who gives you the glasses

Diseases and Refraction Disorders

Conjunctivitis

• Pink eye → Contagious inflammation of the conjunctiva (outer covering)

• Symptoms → Redness, swelling, pain, draining, pus

• Treatment → Antibiotic drops or ointment

• Extremely contagious → Prevent by washing hands

Glaucoma

• Increased pressure in the eye

• Leading cause of blindness

• Symptoms → Lose peripheral (side) vision and bad headache

  • Poor night vision

  • Aching

• Treatment → Medication or surgery

Cataracts

• Lens becomes cloudy → Occurs gradually

• Symptoms → Blurred vision, halos around lights, vision loss

• Treatment → Surgical removal of lens and implant a new lens, glasses, contacts

Diabetic retinopathy

• Too much glucose (sugar) and poor circulation to eye → Eye grows new vessels

• Treatment → Laser surgery to stop the new vessels

Amblyopia

• Lazy eye → Early childhood 

• Poor vision in one eye

• Treatment includes covering the dominant eye and exercises to strengthen the eye → Needs to be treated before 8 or 8 years of age

Myopia

• Nearsightedness → Trouble seeing far

• Lights rays focus in front of the retina

Hyperopia

• Farsightedness → Trouble seeing close

• Light rays focus beyond retina

Presbyopia

• Loss of the ability to focus on near things

• Caused by aging

Astigmatism

• Abnormal shape or curve of cornea

• Treatment → glasses or contact lenses

• Light rays focus on multiple areas of the retina 

Parts of the eye

Retina: Back wall of the eye → holds millions of light sensitive cells

Cones: color detecting nerve cells → when damaged, can lead to color blindness

Rods: black and white detecting nerve cells, sense shape and form → when damaged, can lead to poor night vision

Cornea: dome of clear tissue that focuses light

Iris: Colorful part of the eye

Pupil: Opening in the iris that allows light into the eye

Lens: Focuses the light onto the back of the eye → Lens change shape in order to focus on certain objects

• Thinner for far away, thicker for close up

• Smaller in bright light

Ciliary muscles: muscles that change the shape of the lens

Optic nerve: carries messages to the brain

Brain: Translates the nerve messages into pictures

Sclera: tough white material that covers most of the eye

Tear glands: produces tears

What parts of the eye protect it?

• Eyelashes: keep dirt and other unwanted stuff out of the eyes

• Eyebrows

• Eyelids

Blinking: keeps the eye clean and moist

Depth perception: the ability to judge how near or far objects are

Administering the distance acuity test

1. Questions to ask students.

   1. Name

   2. Date of birth

   3. Do you wear glasses or contact lenses? 

      1. If yes, do you have it with you? If not, can you bring it over?

2. What eye do you test first

   1. Right (OD)

3. How many can they miss per line and pass?

   1. One

4. How many do they miss and have to be retested?

   1. More than one

5. What do you use to retest?

   1. Goodlite