EYES AND VISION Flashcards
What are the 4 External Structures of the eye?
- Eyelids (upper and lower)
- Eyelashes
- Conjunctiva
- Lacrimal apparatus
This transmits visual stimuli to the brain for interpretation, and in doing so, functions as the organ of vision.
Eye
- These are two movable structures composed of skin and two types of muscles: striated and smooth.
- Their purpose is to protect the eye from foreign bodies and limit the amount of light entering the eye.
- They serve to distribute tears that lubricate the surface of the eye.
Eyelids
The eyelids join at two points. What are these?
- Lateral (outer) canthus
- Medial (inner) canthus
WHAT IS THIS?
These are projections of stiff hair curving outward along the margins of the eyelids that filter dust and dirt from air entering the eye.
Eyelashes
WHAT IS THIS?
This is a thin, transparent, continuous membrane that is divided into two portions.
Conjunctiva
What are the two portions of the conjunctiva?
Palpebral conjunctiva and Bulbar conjunctiva
The _______________ lines the inside of the eyelids.
Palpebral conjunctiva
The ____________ covers most of the anterior eye, merging with the cornea at the limbus.
Bulbar conjunctiva
Consists of glands and ducts that lubricates the eye.
Lacrimal apparatus
The ________, located in the upper outer corner of the orbital cavity just above the eye, produces tears.
Lacrimal gland
As the lid blinks, tears wash across the eye and then drain into the __________.
puncta
The _____________ are the six muscles attached to the outer surface of each eyeball. These muscles and associated nerves control six different directions of eye movement.
Extraocular muscles
What are the 6 extraocular muscles?
Four Rectus Muscles
- Superior
- Inferior
- Lateral
- Medial
Two Oblique Muscles
- Superior
- Inferior
The innervation for the extraocular muscles is supplied by three cranial nerves. What are these?
- Cranial Nerve III - Occulomotor
- Cranial Nerve IV - Trochlear
- Cranial Nerve VI - Abducens
The internal layer of the eye consists of two. What are these?
Sclera and Cornea
The _________ is a dense, protective, white covering that physically supports the internal structures of the eye. It is continuous anteriorly with the transparent cornea.
Sclera
The _________ permits the entrance of light which passes through the lens to the retina. It is well supplied with nerve endings, making it responsive to pain and touch.
Cornea
WHAT IS THIS?
- Contact with a wisp of cotton stimulates a blink in both eyes known as the ____________. This reflex is supported by the trigeminal nerve, which carries the afferent sensation into the brain, and the facial nerve, which carries the efferent message that stimulates the blink.
Corneal reflex
This refers to what a person sees with one eye.
Visual Field
The visual field of each eye can be divided into how many quadrants?
Four
What are the 4 Quadrants of our visual field?
- Upper temporal
- Lower temporal
- Upper Nasal
- Lower Nasal
WHAT QUADRANT IS THIS REFERRING TO?
“If I told my patient to look at the wall on the other side of the room and she can see it.”
UPPER TEMPORAL
Explanation:
- This means the patient’s upper outer (peripheral) vision is intact.
- The temporal side detects objects farther away in the periphery.
WHAT QUADRANT IS THIS REFERRING TO?
Likely test: Hold an object low and to the side and check if the patient sees it.
LOWER TEMPORAL
Explanation:
- This quadrant processes objects below and towards the side.
WHAT QUADRANT IS THIS REFERRING TO?
“If I put the pen in front of her at a certain distance and she can see it.”
UPPER NASAL
Explanation:
- The nasal side focuses more on central and near vision.
- If she sees the pen in front, her upper nasal field is intact.
WHAT QUADRANT IS THIS REFERRING TO?
“If my patient said to move the pen nearer because she can’t see it clearly.”
LOWER NASAL
Explanation:
- The lower nasal quadrant may have reduced sensitivity or a blind spot if she struggles to see at a distance but can see when it’s closer.
- This is often tested with a moving target to check how far the patient can detect it.
The temporal quadrants of each visual field extend farther than the nasal quadrants. Thus, each eye sees a slightly different view, but their visual fields overlap quite a bit.
As a result, humans have _____________ in which the visual cortex fuses the two slightly different images and provides depth perception or three-dimensional vision.
Binocular vision (“two-eyed” vision)
Ability to use both eyes together to create a single, (3D) image.
What are the 3 Categories of Vision Impairments?
- Low Vision
- Functional blindness
- Total blindness
A person has limited vision even with corrective lenses but can still perform daily activities with visual aids (e.g., magnifiers, large print, brighter lighting).
- Common Causes: Cataracts, glaucoma, macular degeneration, diabetic retinopathy.
- Example: A person who struggles to read small text even with glasses but can still see large objects and movements.
Low Vision
A person has very limited vision but can still perceive some light, shapes, or movement. They rely more on non-visual methods (e.g., braille, touch, sound) for daily activities.
- Common Causes: Severe glaucoma, retinitis pigmentosa, optic nerve damage.
- Example: A person who can detect light or movement but cannot read, recognize faces, or navigate without assistance.
Functional Blindness
Complete lack of vision with no light perception in either eye. The person relies entirely on non-visual senses for navigation and communication.
- Common Causes: Advanced retinal diseases, optic nerve atrophy, trauma.
- Example: A person who lives in complete darkness and depends on touch, sound, and assistive technology (e.g., braille, guide dogs) to interact with the environment.
Total Blindness
In collecting subjective data through interview, we get the health history of the patient. What are the 4 Histories of the patient we usually get?
- History of Present Health Concerns (Visual Problems), (Other symptoms)
- Personal health History (Glaucoma, Macular Degeneration)
- Family History (Hx of Glaucoma, macular degeneration, refraction errors, allergies)
- Lifestyle and health practices
It is a diagnostic test used to measure the pressure inside the eye (intraocular pressure, IOP) to assess the risk of glaucoma and other eye conditions.
Tonometry
What is the normal eye pressure?
10 to 21 mmHg
Eye pressure with > 22 mmHg has an increased risk for ______________.
Glaucoma
- It is a progressive optic nerve disease that can lead to vision loss.
These are small, shadowy shapes that appear to drift across your field of vision.
This is connected to the problem of our macula.
Floaters
_____________ is an eye disease that affects the macula, the central part of the retina responsible for sharp, detailed vision.
Macular Degeneration
The __________ is a diagnostic tool used to detect and monitor macular degeneration and other central vision problems.
Amsler Grid
How to Use the Amsler Grid:
- Wear your reading glasses (if needed).
- Hold the grid at normal reading distance (about 12–14 inches from your eyes).
- Cover one eye and look at the center dot with the other eye.
- Observe:
✅ Do any lines appear wavy, blurry, or distorted?
✅ Are there any dark or missing areas?
✅ Does the grid look faded or uneven? - Repeat with the other eye.
- If you notice any distortions or abnormalities, consult an eye doctor immediately.
What are the 3 Vision Charts?
- Snellen chart
- Tumble E chart
- Jaeger Test
It is used to test distant visual acuity. The chart consists of lines of different letters stacked one above the other. The letters are large at the top and decrease in size from top to bottom.
The chart is placed on a wall or door at eye level in a well-lighted area. The client stands 20 ft from the chart and covers one eye with an opaque card (which prevents the client from peeking through the fingers). Then the client read each line of letters until they can no longer distinguish them.
Snellen Chart
In a small clinic where there isn’t enough space for a 20-foot distance, healthcare providers use __________ to simulate the correct distance.
mirrors
- The Snellen chart is placed 10 feet away from the patient.
- A mirror is placed behind the patient, reflecting the chart.
- This makes it appear as if the chart is 20 feet away.
It is used if the client cannot read or has a handicap that prevents verbal communication. It is configured just like the Snellen chart but the characters on it are only Es, which face in all directions.
The client is asked to indicate by pointing which way the open side of the E faces. If the client wears glasses, they should be left on, unless they are reading glasses (reading glasses blur distance vision).
Tumble E chart
This is used to assess near vision in client over 40 years of age by holding the pocket screener or newspaper print 14 inches from the eye.
Clients who have decreased accommodation to view closer print will have to move the card or newspaper further away to see it.
Jaeger Test
The ___________ is a hand-held instrument that allows the examiner to view the fundus of the eye by the projection of light through a prism that bends the light 90 degrees.
Ophthalmoscope
It is a condition where the upper eyelid droops over the eye, either partially or completely. It can affect one eye (unilateral) or both eyes (bilateral) and may be congenital (present at birth) or acquired (develops later in life).
Ptosis
A condition where the eyes do not align properly. One eye may turn inward, outward, upward, or downward while the other remains straight.
STRABISMUS (CROSSED EYES)
NOTE:
Types of Strabismus:
✅ Esotropia – One or both eyes turn inward.
✅ Exotropia – One or both eyes turn outward.
✅ Hypertropia – One eye turns upward.
✅ Hypotropia – One eye turns downward.
A condition where the eyes make repetitive, uncontrolled movements (side to side, up and down, or in circles), affecting vision and depth perception.
Nystagmus (Involuntary Eye Movements)
One or both eyes turn inward.
Esotropia
One or both eyes turn outward.
Exotropia
One eye turns upward.
Hypertropia
One eye turns downward.
Hypotropia
A yellowish discoloration of the sclera (white part of the eye), often due to elevated bilirubin levels in conditions like liver disease.
Jaundice
Redness of the eye, which can occur due to irritation, infection (e.g., conjunctivitis), or inflammation.
Erythema
Unequal pupil sizes, which can be normal (physiologic anisocoria) or indicate underlying neurological issues like Horner’s syndrome or third cranial nerve palsy.
Anisocoria
