EYES AND VISION Flashcards by Athea Ordis

What are the 4 External Structures of the eye?

Eyelids (upper and lower)
Eyelashes
Conjunctiva
Lacrimal apparatus

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This transmits visual stimuli to the brain for interpretation, and in doing so, functions as the organ of vision.

Eye

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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

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The eyelids join at two points. What are these?

Lateral (outer) canthus
Medial (inner) canthus

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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

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WHAT IS THIS?

This is a thin, transparent, continuous membrane that is divided into two portions.

Conjunctiva

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What are the two portions of the conjunctiva?

Palpebral conjunctiva and Bulbar conjunctiva

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The _______________ lines the inside of the eyelids.

Palpebral conjunctiva

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The ____________ covers most of the anterior eye, merging with the cornea at the limbus.

Bulbar conjunctiva

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Consists of glands and ducts that lubricates the eye.

Lacrimal apparatus

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The ________, located in the upper outer corner of the orbital cavity just above the eye, produces tears.

Lacrimal gland

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As the lid blinks, tears wash across the eye and then drain into the __________.

puncta

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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

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What are the 6 extraocular muscles?

Four Rectus Muscles

Superior
Inferior
Lateral
Medial

Two Oblique Muscles

Superior
Inferior

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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

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The internal layer of the eye consists of two. What are these?

Sclera and Cornea

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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

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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

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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

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This refers to what a person sees with one eye.

Visual Field

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The visual field of each eye can be divided into how many quadrants?

Four

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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**?

1. Low Vision 2. Functional blindness 3. 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: 1. **Wear your reading glasses** (if needed). 2. Hold the grid at **normal reading distance** (about **12–14** inches from your eyes). 3. **Cover one eye** and look at the **center dot** with the other eye. 4. Observe: ✅ Do any lines **appear wavy, blurry, or distorted?** ✅ Are there any **dark or missing areas**? ✅ Does the grid look **faded or uneven**? 5. Repeat with the **other eye.** 6. If you notice **any distortions or abnormalities**, consult an **eye doctor immediately.**

What are the **3 Vision Charts**?

1. Snellen chart 2. Tumble E chart 3. 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