Health Assessment: Eyes and Ears Study Guide

Visual Reflexes and Physiology

• Pupillary Light Reflex: This is the normal constriction of pupils when bright light shines on the retina.

  • It is a subcortical reflex arc, meaning the person has no conscious control over it.

  • Sensory Afferent Link: Cranial Nerve II ($CN\,II$), the optic nerve.

  • Motor Efferent Path: Cranial Nerve III ($CN\,III$), the oculomotor nerve.

  • Direct Light Reflex: Occurs when one eye is exposed to bright light, resulting in the constriction of that specific pupil.

  • Consensual Light Reflex: Simultaneous constriction of the opposite pupil happens because the optic nerve carries the sensory afferent message which then synapses with both sides of the brain.

• Fixation: A reflex direction of the eye toward an object that attracts a person's attention.

  • The image is fixed in the center of the visual field, specifically the fovea centralis.

• Accommodation: This is the adaptation of the eye for near vision.

  • It is accomplished by increasing the curvature of the lens through the movement of ciliary muscles.

  • Although the lens cannot be observed directly, the following observable components of accommodation include:

    • Convergence: Motion toward the axes of the eyeballs.

    • Pupillary constriction.

Developmental Competence: The Aging Adult (Eyes)

• Structural Changes: Aging leads to a loss of elasticity, atrophy of fat and muscle tissue, and decreased tear production.

• Presbyopia: The lens loses elasticity, becoming hard and glasslike. This decreases the ability of the lens to change shape to accommodate for near vision. This typically occurs by age $40$ to $45$.

• Visual Acuity: May diminish gradually after age $50$, with more significant decline after age $70$.

• Floaters: These appear due to the accumulation of debris in the eye.

• Common Causes of Decreased Visual Functioning:

  • Cataract Formation: Lens opacity resulting from the clumping of proteins in the lens. By age $80$, most individuals in the US have cataracts or have undergone cataract surgery.

  • Diabetic Retinopathy (DR): Blindness caused by oxidative damage and inflammation of the retina.

  • Glaucoma: Increased intraocular pressure leading to compression of the optic nerve.

  • Age-Related Macular Degeneration (AMD): Loss of central vision due to the degeneration of cells in the macula of the retina.

Genetics, Environment, and Culture (Eyes)

• Variability: Culturally based variability is present in the color of the iris and retinal pigmentation.

• Glaucoma Risk Factors: Incidence increases with age. Black Americans age $40$ years and older are at the highest risk, followed by Hispanic/Latinos and Whites ($NIH$, $2021$).

• AMD Risk Factors: Increased prevalence is seen in White Americans over the age of $75$ ($NIH$, $2021$). Modifiable risk factors include diet and smoking.

• Cataracts: Family history and environment are established risk factors.

Subjective Data and Patient History (Eyes)

• Vision Difficulty: Includes decreased acuity, blurring, and blind spots (scotoma).

  • Questions: Did it come on suddenly or slowly? One eye or both? Constant or intermittent? Halos, rainbows, or rings around objects? Night blindness?

• Pain: Questions involve sudden onset, quality (burning, itching, sharp, stabbing, deep aching), and sensitivity to light (photophobia).

• Strabismus and Diplopia: History of crossed eyes or double vision.

• Redness and Swelling: Any infections or seasonal occurrences.

• Watering and Discharge: Excessive tearing (epiphora) or matter in the eyes; color of discharge and hygiene practices.

• Past History: Ocular problems, injuries, surgeries, or allergies.

• Glaucoma Check: Last test results and family history.

• Corrective Lenses: Use of glasses or contact lenses, last prescription check, and care/cleaning habits.

• Patient-Centered Care:

  • Environmental conditions at home/work (use of goggles).

  • Current medications (systemic, topical, or specific eye drops).

  • Smoking status.

  • Coping mechanisms for vision loss (large print, audio, braille, maintaining consistent home layout).

Objective Visual Assessment and Physical Examination

• Central Visual Acuity:

  • Snellen Alphabet Chart: The most accurate measure of visual acuity. If the person cannot see the largest letters, shorten the distance and record (e.g., $10/20$). If lower, check for finger counting or light perception.

• Near Vision:

  • Tested with a handheld vision screener like a Jaeger card for those reporting difficulty reading.

• Diagnostic Positions Test:

  • Moving the patient through the six cardinal positions of gaze in a clockwise direction.

  • Assesses for extraocular muscle ($EOM$) weakness, nystagmus, or lid lag.

• General Inspection:

  • Observe symmetry, facial expression, and ability to move without bumping into objects.

• Eyebrows, Eyelids, and Lashes:

  • Eyebrows: Present bilaterally, move symmetrically, no lesions/scaling.

  • Palpebral fissures: Horizontal in non-Asians; upward slant in Asians.

  • Lids/Lashes: Evenly distributed, lashes curve outward.

• Eyeballs:

  • Aligned normally. African Americans may normally have a slight protrusion beyond the supraorbital ridge.

• Conjunctiva and Sclera:

  • Sclera is normally white. In African Americans, it may be gray-blue or contain small brown macules (freckles) and yellowish fatty deposits (not to be confused with jaundice).

  • Conjunctiva should be clear, moist, and glossy.

• Lacrimal Duct: Puncta drain tears; excessive tearing may indicate a blockage of the nasolacrimal duct.

• Iris and Pupil:

  • Red Reflex: Caused by light reflecting off the inner retina.

  • PERRLA: Pupils Equal, Round, React to Light, and Accommodation.

  • Pupil size should be measured in millimeters ($mm$) before and after reflex testing.

  • Testing for Accommodation: Focus on a distant object (dilates), then shift to a near object (~$7$ to $8\,cm$ or $3\,inches$ from nose), resulting in pupillary constriction and convergence.

Pupil Size Abnormalities

• Anisocoria: Unequal pupil sizes; may signal neurological issues or trauma.

• Miosis: Persistent constriction of pupils; associated with drug use, brain injury, or disease.

• Mydriasis: Abnormal dilation and fixation of pupils; associated with head injuries, drugs, or neurological disorders.

Ear Anatomy and Physiology

• Pathways of Hearing:

  • Air Conduction ($AC$): Normal pathway, more efficient.

  • Bone Conduction ($BC$): Bones of the skull vibrate and transmit sound directly to the inner ear and CN VIII.

• Equilibrium: The labyrinth in the inner ear (comprising three semicircular canals) provides information about the body's position in space.

  • Inflammation of the labyrinth causes misinformed signals to the brain, leading to a staggering gait and vertigo.

Types of Hearing Loss

• Conductive Hearing Loss: A partial loss where increasing sound level helps. Causes include:

  • Impacted cerumen (earwax).

  • Foreign bodies or pus.

  • Perforated tympanic membrane ($TM$).

  • Decreased mobility of ossicles.

• Sensorineural (Perceptive) Hearing Loss: Pathology involving the inner ear, Cranial Nerve VIII ($CN\,VIII$), or auditory areas of the cerebral cortex. Increasing amplitude may not help understanding. Causes include:

  • Presbycusis: Gradual nerve degeneration with aging.

  • Ototoxic drugs.

• Mixed Hearing Loss: A combination of conductive and sensorineural loss in the same ear.

Developmental Competence: Aging Adult (Ears)

• Otosclerosis: A common cause of conductive hearing loss in young adults ($20$ to $40$ years). It involves gradual hardening that fixes the stapes footplate in the oval window, impeding sound transmission.

• Presbycusis: Occurs in $2/3$ of the population over age $70$.

  • Charactersitics: High-frequency tone loss occurs first, followed by impaired sound localization.

  • Words may sound garbled; consonants are hard to hear; the person feels people are "mumbling."

• Cilia and Cerumen: Cilia become coarse and wiry at the canal opening. Cerumen may impact, causing conductive loss.

• Physical Changes: Pendulous earlobes with linear wrinkling; eardrum ($TM$) may appear whiter, more opaque, and thicker.

Genetics and Cerumen Types

• Dry Cerumen: Gray and flaky. Prevails in Asians and American Indians.

• Wet Cerumen: Honey brown and moist. Common in Caucasians and African Americans.

• Cerumen type is genetically determined and unrelated to hygiene.

Ear Assessment and Physical Examination

• Subjective Data: Pain, infections, discharge (otorrhea), hearing loss, environmental noise, tinnitus (ringing), vertigo, and self-care behaviors.

• Objective Clues of Hearing Loss: Lip reading, straining forward, posturing the head, inappropriate voice volume, or distorted speech.

• Inspection and Palpation:

  • External Ear: Equal size bilaterally. Darwin’s tubercle is a small painless nodule at the helix (congenital variation).

  • Tenderness: Move pinna and push on tragus; palpate mastoid process. These should not be painful.

  • External Auditory Meatus: Check for redness, swelling, or discharge. Note color and odor of any discharge.

• Hearing Acuity Tests:

  • Whispered Voice Test: Stand $arm\text{'s length}$ ($2\,ft$) behind the person. Test one ear at a time while masking the other by pushing the tragus. Whisper two-syllable words after exhaling.

  • Audiometric Testing: Used if the person reports hearing difficulty.

• Vestibular Apparatus:

  • Romberg Test: Assesses the ability of the inner ear to maintain standing balance; also tests the cerebellum and proprioception.

Examination Summary Checklist

• Eyes:

  • Inspect external structures (conjunctiva, sclera, drainage).

  • Assess $EOMs$ ($CN\,III$ - Oculomotor, $CN\,IV$ - Trochlear, $CN\,VI$ - Abducens) via six cardinal fields of gaze.

  • Assess PERRLA: Equality, roundness, reaction to light (direct/consensual), and accommodation (convergence/pupil size).

• Ears:

  • Inspect auricle (size, shape, position, skin condition).

  • Check auricle and tragus for tenderness.

  • Evaluate external auditory meatus.