MOD 6- Chapter 11: Essential Eye Assessment - Study Notes (Chapter 11)

Structure and Function of the Eye

• The eye is a complex organ. Sight occurs when the eyes and brain work together to detect, translate, and interpret incoming visible spectrum electromagnetic radiation.

• Visual information travels from the eye to the brain where perception and interpretation occur.

Anatomy and Physiology of the Eye

• External Structures

• Internal Structures

• Cranial Nerves involved in eye movements: CN III, CN IV, CN VI

• Extraocular Structures

• Intraocular Structures

Diagnostics

• Comprehensive dilated eye exam: dilates the pupil to look directly at the retina and internal structures.

• Tonometry: device to measure intraocular pressure (IOP), denoted as $ext{IOP}$.

Conjunctiva (Front of Eye Membrane)

• Question: What is the thin membrane covering the front of the eye and inner eyelids called?

  • Options: Conjunctiva, Tarsal plates, Lacrimal ducts, Aqueous humor

  • Correct answer: Conjunctiva

• Function of conjunctiva:

  • Produces mucous to lubricate the eye.

  • Permits movement of the eyeball.

• Conjunctiva coverage:

  • Bulbar conjunctiva covers the front of the eye.

  • Palpebral conjunctiva covers the inner eyelids.

Health History

• Past medical history to review:

  • Eye problems or diseases (e.g., cataracts, glaucoma, macular degeneration)

  • Eye surgery (LASIK: laser-assisted in situ keratomileusis; reshapes the cornea to correct refractive errors: farsightedness, nearsightedness, or astigmatism)

• Family history of eye conditions.

• Health promotion questions:

  • When was your last eye examination?

• Current vision history:

  • Loss of visual acuity or loss of visual field

  • Eyewear use: glasses, contact lenses

  • Difficulty reading or seeing at distances

• Common current symptoms to ask about:

  • Drainage or redness

  • Irritation or itching

  • Double or blurry vision

  • Difficulty seeing at night

  • Eye pain or dry eyes

  • Seeing white or dark specks, or flashing lights

Health History (continued) – Contact Lens Questions

• If patient wears contact lenses (e.g., five years):

  • Do you wear contact lenses?

  • Are they soft or hard?

  • Do you sleep with them on?

  • Do you have any problems wearing contact lenses?

  • Do you experience redness or irritation?

• Correct focus (from the transcript): B, C, D, E are the essential follow-up questions; i.e., you should ask about type, comfort, sleep, problems, and irritation given the history.

Sequence of Assessment

• Sequence to follow:

  • Inspect the eye

  • Assess visual acuity

  • Assess for color blindness

  • Assess central vision

  • Assess peripheral vision

  • Assess ocular motility

  • Assess for accommodation

  • Assess pupil size and consensual response

Technique 11-1: Inspecting the Eyes

• Purpose: To assess external eye structures.

• Equipment: Tangential light source and gloves

• Inspect the eyelids:

  • Observe that eyelids open and close completely

  • Assess for any drainage

• Inspect the eyelashes for:

  • Distribution

  • Drainage

• Inspect the eyebrows:

  • Symmetry, hair, skin

• Inspect the cornea and lens:

  • Use a light source to inspect cornea for smoothness and clarity

  • Inspect lens for clarity, color, and shape

• Inspect the sclera for color and surface area

• Inspect the conjunctiva (gloved): slide lower eyelids down to assess mucosa; inspect color when patient looks up

• Inspect the lacrimal duct:

  • Gloved palpation for swelling or excessive tearing

• Inspect palpebral fissures:

  • Distance between upper and lower lids for symmetry

  • Compare fissures bilaterally

• Look for abnormal involuntary eye movements

Normal Findings for Inspecting the Eyes

• Eyes are symmetrical; eyelids close completely; eyelashes evenly distributed; eyebrows evenly distributed without flaky skin

• Cornea is clear; lens is transparent with no opacities

• Pupils equal in size; iris color varies (blue, green, brown, hazel); iris smooth; controls diameter and size of the pupil

• Sclera white; conjunctiva pink and moist; lacrimal ducts clear with no swelling

• Palpebral fissures equal bilaterally

• No abnormal involuntary movements

Abnormal Findings (Inspecting the Eyes)

• Eyes asymmetrical or protruding; eyelids don’t open or have drainage; eyelash drainage; eyebrows asymmetrical

• Cornea rough or not smooth; lens clouding; sclera yellow (icterus)

• Conjunctiva red or inflamed; lacrimal ducts red or inflamed

• Palpebral fissures not equal; abnormal involuntary movements

• Common conditions: blepharitis, blocked lacrimal duct, cataract, conjunctivitis, corneal abrasion, ectropion, entropion, exophthalmos, hordeolum, icterus, pterygium, ptosis

Technique 11-2: Assessing for Visual Acuity

• Purpose: To measure and assess visual acuity

• Equipment: Snellen chart

• Distance: patient stands at $20 ext{ ft}$ from the chart

• Method: patient reads lines aloud from top to bottom; read left to right within each line

• Continue until unable to identify one or two letters in a line; repeat with opposite eye; then with both eyes open; document the last line read correctly for each assessment

Visual Acuity Findings

• Normal distant visual acuity: $20/20$

• Abnormal findings: higher denominator indicates poorer distant visual acuity

• Conditions often associated: myopia, hyperopia, presbyopia

• Legal blindness definitions may be discussed in the context of acuity

Practice Question: Central Vision Assessment (Amsler Grid Related)

• Question: You are assessing a patient’s central vision; which assessment is used?

  • Options: Snellen chart, Amsler grid, Ishihara plate, E-chart

  • Correct answer: Amsler grid

Technique 11-3: Assessing for Color Blindness

• Purpose: To assess the ability to distinguish colors

• Equipment: Ishihara plate

• Procedure: Have patient look at the Ishihara plate and identify the embedded figures or numbers within $3 ext{ to } 5 ext{ seconds}$

• Normal findings: patient correctly identifies the colors

• Abnormal findings: patient incorrectly identifies colors or cannot see them; may indicate color blindness

Technique 11-4: Using the Amsler Grid for Central Vision

• Purpose: To assess central vision

• Equipment: Amsler grid, marker

• Position: patient may wear reading glasses; hold grid at the same distance as reading material

• Procedure: patient covers the left eye and focuses on the central dark dot with the right eye; patient notes if any lines are distorted, broken, blurred, or missing/dark areas; repeat on the other eye; patient marks non-clear areas on the grid

• Normal findings: no distortion; no missing areas

• Abnormal findings: lines distorted/broken/blurred; may indicate macular degeneration

Technique 11-5: Confrontation Test

• Purpose: To assess peripheral vision, overall field of vision, and blind spots

• Procedure:

  • Face the patient; cover your right eye; patient covers left eye with a hand; look directly into your uncovered eye

  • Move the fingers of your left hand into the patient’s field of vision from four angles:

  • Temporal: $90^ op$

  • Nasal: $60^ op$

  • Superiorly: $50^ op$

  • Inferiorly: $70^ op$

  • Instruct the patient to say 'now' when they can see the fingers and to state how many fingers they see

Confrontation Test (continued)

• Normal findings: patient sees your fingers at the same time as you and correctly states the number of fingers

• Abnormal findings: patient does not see your fingers; may indicate a blind spot (scotoma) or hemianopia

Technique 11-6: Testing for Ocular Motility

• Purpose: To assess the functioning of the ocular muscles

• Equipment: Penlight (optional)

• Procedure:

  • Hold an object about $12 ext{ in}$ (about 30 cm) from the patient’s face; instruct patient not to move head, follow the object with the eyes only; if head movement occurs, gently stabilize the head

  • Move the object in six positions using a wide 'H' or star pattern; pause between lateral and upward movements

• Normal findings: eyes move in a smooth, coordinated pattern through all six cardinal directions

• Abnormal findings: inability to follow the pattern; may indicate diplopia or nystagmus

Practice Question: Ocular Motility

• Question: Which finding indicates weakness or problems with the ocular muscles?

  • Options: Confrontation test, Consensual response test, Ocular motility test, Accommodation test

  • Correct answer: Ocular motility test

Technique 11-7: Testing for Convergence and Accommodation

• Purpose: To assess the accommodation reflex of the eye

• Equipment: Penlight (optional)

• Procedure:

  • Hold a penlight or finger about $14 ext{ in}$ (about 35 cm) in front of the patient’s eyes

  • Instruct patient to focus on the object for about $30 ext{ s}$; then move the object toward the patient’s nose

• Normal findings: Both eyes converge and both pupils constrict simultaneously

• Abnormal findings: Pupils do not converge or constrict

Technique 11-8: Inspecting Pupil Size and Consensual Response

• Purpose: To assess the pupillary light reflex (controls pupil diameter) and to assess the integrity of the optic pathways via consensual response

• Equipment: Penlight and pupil-size measurement chart

• Procedure:

  • Stand in front of the patient; use the penlight to inspect pupil color, shape, and symmetry

  • Assess direct reaction (pupil constricts with light) and consensual reaction (other pupil constricts when light is shone in the first eye)

  • Measure the size of each pupil in millimeters

• Normal findings:

  • Pupils constrict in response to light

  • Both eyes have a consensual response to direct light

  • Pupil is round and black

  • Both pupils are equal size; diameter $2 ext{ mm} ext{ to } 8 ext{ mm}$

• Abnormal findings:

  • Pupils unequal in size or both dilated or constricted or fixed

  • Terms: anisocoria, mydriasis, miosis, Horner’s syndrome

Practice Question: Ocular Motility vs Pupil Reflex

• Question: Which technique assesses weakness or problems with the ocular muscles?

  • Answer: Ocular motility test

Technique 11-9: Assessing With the Ophthalmoscope

• Purpose: To assess the internal structures of the eye by directing light through the pupil to illuminate internal structures

• Equipment: Ophthalmoscope

• Procedure:

  • Turn on the ophthalmoscope; dial to $0$ diopters

  • Dim the room lights; instruct the patient to look at a distant object or focal point over your shoulder

  • Place nondominant hand on patient’s forehead or shoulder; hold the ophthalmoscope in your right hand

  • Position about $12 ext{ in}$ away and at a $15^ op$-degree lateral angle to the patient’s line of vision

  • Look through the aperture with your right eye; direct light into the patient’s right pupil and locate the red reflex

  • Assess for any opacities interrupting the red reflex

Assessing Internal Structures

• Continue to move toward the pupil and adjust the lens disc to positive numbers to assess the anterior interior structures

• Adjust the lens disc to minus or red numbers to assess posterior structures

• Follow a blood vessel to the optic disc

The Optic Disc

• Assess for:

  • Color: yellow/orange to creamy pink

  • Shape: round or oval

  • Disc outline: sharp or cloudy

  • Central physiologic cup (if present): brighter yellowish/white color

The Retina and Macula

• Retina assessment:

  • Arteries: light red; smaller diameter

  • Veins: dark red; larger diameter

  • Retinal background: red-orange

• Instruct patient to look directly into the light source to assess the macula

• Macula: yellow, oval shape

• Repeat on the opposite eye

Normal Findings for Ophthalmoscopy (Internal Structures)

• Optic disc: round; defined borders; color creamy yellow, yellow-orange, or pink

• Physiologic cup: slightly depressed, lighter in color

• Cup-disc ratio: cup is less than half of optic disc diameter; ext{cup-disc ratio} < frac{1}{2}

• Retinal arteries: light red, progressively narrower away from the optic disc

• Retinal veins: darker red, progressively narrower away from the optic disc

• Retinal background: uniform red-orange color

• Macula: oval to round; darker yellow; highly pigmented

Abnormal Findings (Ophthalmoscopy)

• Cotton wool spots

• Diabetic retinopathy

• Drusen bodies

• Papilledema

Healthy People 2030 Vision Objectives

• Goal: Prevent sensory and communication disorders and improve quality of life for people who have them (ODPHP, 2020)

• Vision objectives emphasize evidence-based interventions to preserve sight and prevent blindness

Patient Education (Eye Health Promotion)

• Comprehensive eye examination

• Nutrition

• Protective eyewear

• Protect eyes from ultraviolet rays

• Give eyes a rest

• Contact lens hygiene

Practice Questions and Answers (ClickerCheck Summaries)

• Central vision assessment: Amsler grid is used for assessing central vision (Answer: B)

• Visual field assessment: Confrontation test is used for peripheral vision; abnormal findings may include scotoma or hemianopia

• Distinguishing ocular muscle issues: Ocular motility test assesses weakness or problems with ocular muscles

• Normal vs abnormal sclera in a patient with daily morning specks: Sclera should be white; icterus (pale yellow) indicates elevated bilirubin

• Ophthalmoscope positioning for red reflex: about $12 ext{ in}$ away and at a $15^ op$ lateral angle; hold the ophthalmoscope in the right hand (Answer: D)

Quick Reference Numeric and Physiological Details (LaTeX)

• Snellen distant visual acuity: $20/20$

• Pupil diameter range (normal): $2 ext{ mm} ext{ to } 8 ext{ mm}$

• Cup-disc ratio: ext{Cup-Disc ratio} < frac{1}{2}

• Confrontation angles: $90^ op, 60^ op, 50^ op, 70^ op$

• Distance for Snellen/visual exams: $20 ext{ ft}$

• Ocular motility testing distance: $12 ext{ in}$ (about 30 cm)

• Convergence and accommodation focusing distance: $14 ext{ in}$ (about 35 cm); duration: $30 ext{ s}$

• Ophthalmoscope positioning: $12 ext{ in}$ away; angle $15^ op$ to the side; diopter setting $0$