Eyes

The structures of the outer eye work together to protect the eye from light and foreign bodies, while the structures of the inner eye function to optimize vision. Movement of the eyes is controlled by six muscles, which are innervated by three cranial nerves.

Eyelids

Conjunctiva

Lacrimal Gland

Eye Muscles

  • Composed of skin, striated muscle, tarsal plate, and conjunctiva

  • Clear, thin mucous membrane

    • Palpebral – coats the inside of the eyelid

    • Bulbar – covers the outer surface of the eye

  • In the temporal region of the superior eyelid

  • Superior, inferior, medial, lateral rectus

  • Superior and inferior oblique

  • Outer fibrous layer – sclera and cornea

  • Middle layer – choroid and ciliary body/iris

  • Inner layer – retina

Sclera

Cornea

Uvea – contains iris, ciliary body, choroids

Lens

Retina

  • White of the eye

  • Continuous with the sclera anteriorly

  • Clear

  • Iris – circular, contractile muscular disc that contains the pigment of the eye

  • Ciliary body

  • Choroid – pigmented, vascular layer between the retina and the sclera

  • Biconvex, transparent structure, immediately behind the iris

  • Supported by fibers arising from the ciliary body

  • Sensory network of the eye

  • Major landmarks of the retina include:

    • Optic disc, central retinal artery and vein, macula


Innervated by cranial nerves III, IV, and VI. Cranial nerve II (optic nerve) connects the eye to the brain.

Eyelids

Conjunctiva

Lacrimal gland

  • Distribute tears over eye surface

  • Limit the amount of light that enters the eye

  • Protect the eye from foreign bodies

  • Protect the eye from foreign bodies and desiccation (dryness)

  • Produces tears that moisten the eye

Sclera

Cornea

Uvea

Lens

Retina

  • Supports the internal eye structures

  • Sensory innervation for pain

  • Major part of the refractive power of the eye

  • Iris contains pigment that produces eye color

  • Pupil – Central aperture of the iris; dilates and contracts to control light entering retina

  • Ciliary body – produces aqueous humor and contains muscles controlling accommodation

  • Choroid – pigmented, vascular layer supplying oxygen to the outer layer of the retina

  • Contraction/relaxation of the ciliary body changes lens thickness

  • Lens thickness changes allow images from varied distances to be focused on the retina

  • Transforms light impulses into electrical impulses that the cortex of the brain interprets as visual objects; transmitted through:

    • Optic nerve

    • Optic tract

    • Optic radiation

    • Visual cortex

    • Consciousness in the cerebral cortex

  • Eye movement is controlled by six muscles:

    • Superior rectus muscle

    • Inferior rectus muscle

    • Medial rectus muscle

    • Lateral rectus muscle

    • Superior oblique muscle

    • Inferior oblique muscle

  • The muscles are innervated by cranial nerves III, IV, and VI.

    • Oculomotor (III) – elevates and retracts upper eyelid

    • Trochlear (IV) – innervates superior oblique muscle

    • Abducens (VI) – innervates lateral rectus muscle

History of Present Illness: Eyes

question the patient about:

  • Red eye, conjunctival redness

  • Difficulty with vision

  • Pain/headache

  • Foreign body sensation

  • Current illness or similar symptoms in other members of the household

  • Allergies

  • Secretions

  • Photosensitivity (sensitivity to light)

  • Current medications

Onset, Duration, Location

Associated Symptoms

Aggravating/Alleviating Factors, Effort to Treat, Medication

Character, Severity, Predisposing Factors

  • Onset: gradual or abrupt; trauma to the eye

  • Duration: minutes, hours, days, weeks, constant, intermittent, seasonal

  • Location: unilateral, bilateral

  • Headache, face pain

  • Tenderness over sinuses

  • Ear/nose drainage

  • Fever

  • Swelling

  • Itching

  • Fatigue, malaise

  • Halos around lights

  • Photosensitivity

  • Sensation of something in the eye

  • Aggravating factors: palpation, movement, light

  • Alleviating factors: medication

  • Efforts to treat: heat/cold therapy, medications

  • Medications: analgesics, NSAIDs, narcotics, thyroid preparations

  • Character: throbbing, pounding, boring, dull, nagging, pressure, pain with movement, relieved by movement, constant, intermittent

  • Severity: using self-reporting scale

Predisposing factors:

  • Fever, fatigue, stress, allergies

Medical Surgical History

ask the patient about a history of:

  • Eye trauma

  • Eye surgery

  • Chronic illnesses affecting vision

    • Hypertension

    • Atherosclerotic cardiovascular disease (ASCVD)

    • Diabetes

    • Glaucoma

    • Thyroid dysfunction

    • Autoimmune disease

    • Human immunodeficiency virus (HIV)

Family History

question the patient about a family history of:

  • Headaches (type and character)

  • Thyroid dysfunction

  • Retinal cancer (retinoblastoma)

  • Glaucoma

  • Macular degeneration

  • Diabetes

  • Hypertension and other diseases affecting eye health

  • Color blindness

  • Cataracts

  • Retinal detachment

  • Retinitis pigmentosa

  • Allergies

  • Near/farsightedness

Personal/Social Histo

Personal/Social History

Potential Questions to Ask

Environmental hazards

  • “What type of environmental hazards are you exposed to at work?”

  • “Are you exposed to dry heat, chemicals, or other materials that could cause eye trauma?”

Nutrition

  • “What types of foods do you eat on a regular basis?”

  • “Do you typically eat foods with a lot of sugar?”

Tobacco/alcohol use

  • “What types of tobacco products do you use?”

  • ”How many cigarettes do you smoke each day?”

  • “How much alcohol do you drink during a typical week?”

Recreational drug use

  • “What types of recreational drugs do you use?”

Physical activity

  • “What type of physical activity or sports do you participate in?”

Protective devices

  • “What types of protective devices do you use during work or activities that might endanger you?”

Corrective lenses

  • “When was your last eye examination?”

  • “How long have you worn glasses/contacts?”

  • “Do you sleep in your contact lenses?”

  • “How do you clean your contact lenses?”

  • “How adequate is your vision with your glasses/contact lenses?”

Visual Testing of the Eye

  • Central Vision (Visual Acuity Testing)

    • Snellen charts: Pt stands 20 feet from chart. Most accurate way to test central vision. Test each eye independently. Numerator is distance pt is standing and denominator is distance that a normal eye can see.

    • Lea cards

    • Landolt C eye chart

    • HOTV eye chart

    • If the patient’s vision is less than 20/20, the nurse can use the pinhole test to determine whether vision loss is a refractive error.

  • Near Vision

    • Rosenbaum Pocket Vision card

    • Jager near vision card

  • Peripheral Vision: tested using the nasal, temporal, superior, and inferior fields of gaze:

    • Have the patient cover the right eye; the nurse’s left eye is covered.

    • The nurse and patient look into each other’s eyes.

    • The nurse fully extends the arm and moves the hand centrally, having the patient report when the fingers are first seen.

External Exam of Eye

Inspection

Palpation

  • Symmetry

  • Eyebrow size and extension, hair texture

  • Orbital and periorbital area (edema, puffiness, sagging tissue)

  • Eyelid

    • Position

    • Ability to open and close completely

    • Eyes lightly and tightly closed

    • Fasciculations or tremors

    • Eyelashes

    • Margins for flakiness, redness, and swelling

  • Conjunctiva for erythema and exudate

  • Corneal clarity using tangential light

  • Iris and pupil: shape, color, regularity, size, response to light, constriction, and accommodation PERRLA

  • Lens color

  • Sclera color and presence of a senile hyaline plaque

  • Lacrimal region: color, drainage, tear production

  • Eyelids

  • Orbital area

  • Lacrimal region

  • Corneal sensitivity with a wisp of cotton

Extraocular Muscles

  • Eye movement is controlled by cranial nerves III (oculomotor), IV (trochlear), and VI (abducens), and the six extraocular muscles.

Internal Eye Inspection: ophthalmoscope

  • Red reflex: Reddish glow of eye. Stand 10 ft away, use opthalmoscope and observe for red reflex

  • Fundus

  • Blood vessel characteristics (follow blood vessels distally looking for crossing of arterioles and venules)

  • Disc characteristics

  • Retina

  • Macula characteristics

Normal Findings

Eye Inspection

Eye Palpation

Ophthalmoscope Examination

  • Eyebrows symmetrical, may be thinned if plucked or waxed

  • No edema or puffiness around orbital area

  • Eyelids cover a portion of the eye when it is opened, close completely without fasciculation/twitching

  • Eyelashes present on both lids, turned outward

  • Conjunctivae clear

  • Sclera white and visible above iris when eyes are open wide

  • Slight elevation and central depression of lacrimal gland

  • Brisk bilateral blink reflex/light reactivity

  • No visible blood vessels

  • Clearly visible iris, color similar bilaterally

  • Pupils round, regular, equal in size

    • Constrict when light briefly, indirectly passed over the pupils

    • Each pupil constricts with consensual response of opposite pupil

    • Constrict when focus is on near object/dilate when focus changes from near object to distant

  • Extraocular movements:

    • Smooth, coordinated movement

    • Few, horizontal, nystagmic beats

    • Red reflex symmetrical in both eyes

  • Eyelids nontender, without nodules

  • Can gently push eye into orbit without discomfort

  • Clear lens

  • Yellow or pink background (depending on race)

  • Possible crescents or dots of pigment at disc margin, usually temporally

  • Possible venous pulsations (arteriole/venule ratio 3:5 or 2:3)

  • Disc characteristics:

    • Yellow to creamy pink

    • Sharp, well-defined margin

    • 1.5-mm diameter

  • Macula characteristics:

    • Yellow dot surrounded by deep pink

Eye Variations in Children

  • Between 3 and 5 years of age, vision is typically 20/40. It reaches 20/30 or better by age 6.

Eye Variations: Older Adult

  • Weakened accommodation due to progressive weakness

  • Loss of lens clarity

  • Cataract formation

  • Decreased/distorted central vision

  • Excess tearing

  • Dry eyes

  • Yellow color or brown spots on sclera

  • Nocturnal eye pain

Abnormal Findings

  • Myopia: a common refractive error where close objects appear clear but distant objects are blurry, usually caused by the eyeball growing too long or the cornea curving too steeply

  • Amblyopia:a visual development disorder where the brain fails to process input from one eye, often resulting in reduced vision in that eye. It can be caused by strabismus, significant differences in refractive error between the two eyes, or other issues that interfere with clear vision during early childhood.

  • Presbyopia: a gradual loss of the eye's ability to focus on nearby objects, commonly associated with aging, typically beginning in the early to mid-40s when the lens becomes less flexible.

  • Limited field of vision temporally, 50 degrees superiorly, 70 degrees inferiorly

  • Hyperopia: a common refractive error also known as farsightedness, where distant objects can be seen more clearly than nearby objects due to the light entering the eye being focused behind the retina. This condition can be corrected with glasses, contact lenses, or refractive surgery.

  • Strabismus: a disorder in which the eyes do not properly align with each other when looking at an object. This misalignment can lead to double vision or the brain ignoring input from one eye, potentially resulting in amblyopia (lazy eye) if left untreated.

  • Exophthalmos: Eyes protrude. Surprised look

  • Enophthalmos: Sunken eyes, which can be caused by various factors including aging, dehydration, or certain medical conditions that lead to loss of fat or tissue around the eyes.

  • Blepharitis: Inflammation of eyelids, often characterized by red, swollen eyelids, crusted eyelashes, and discomfort. It can result from bacteria, skin conditions, or malfunctioning oil glands.

  • Chalazion: A localized swelling on the eyelid caused by a blocked meibomian gland, leading to a firm lump that may be painless, though it can cause discomfort and cosmetic concerns.

  • Hordeolum: An acute infection of the sebaceous glands of the eyelid, commonly known as a stye, presenting as a red, painful bump near the edge of the eyelid, often resulting from bacterial infection.

  • Dacryocystitis: A condition characterized by the obstruction of the nasolacrimal duct, leading to tear accumulation and potential infection, often resulting in excessive tearing and swelling in the inner corner of the eye.

  • Monocular Blindness: Pupils won’t respond to light in blind eye. Light shined in good eye will cause both pupils to constrict

  • Eye Inspection

    • Eyebrows asymmetrical, ending short of outer canthus, coarse texture

    • Orbital edema, puffiness, sagging tissue below orbit, xanthelasma (slightly raised, oval, yellow-tinted fatty deposit lesions)

    • Ectropion (lower lid turned away from the eye) or entropion (lid turned toward the globe)

    • Exophthalmos (bulging of the eyes, indicative of hyperthyroidism)

    • Fasciculations of eyelid when lightly closed

    • Ptosis (drooping eyelid)

    • Lagophthalmos (closed lids do not completely cover the eye)

    • Flakiness, redness, swelling in eyelid margin

    • Conjunctivae erythematous

    • Sclera yellow, green, dark, or rust-colored

    • Exudate

    • Pterygium (abnormal growth of conjunctiva that extends over cornea)

    • Corneal opacity

    • Enlarged lacrimal gland

    • Dry eyes

    • Inability to blink

    • Visible blood vessels

    • Miosis (pupil constriction to less than 2 mm)

    • Mydriasis (pupil dilation of more than 6 mm and failure to constrict with light)

    • Anisocoria (unequal pupil size)

    • Pupils continue to dilate when the light shines into them

    • Extraocular movements:

      • Sustained, jerking nystagmus, suggestive of extraocular weakness

      • Exposure of sclera from lid lag

      • Inability to move eye in all directions

      • Eye moves during cover-uncover test

  • Eye Palpation

    • Nodules on eyelids

    • Firm eye that resists palpation

    • Drooping

  • Ophthalmoscope Examination

    • Cloudy, opaque lens

    • Shallow chamber

    • Mydriasis

    • No red reflex

    • Discrete areas of pigmentation away from disc

    • Lesions

    • Drusen bodies

    • Hemorrhages

    • Nicking, tortuosity

    • Myelinated nerve fibers

    • Papilledema

    • Glaucomatous cupping

Documentation of History of Present Illness

  • Discomfort or photophobia

  • Redness

  • Watery discharge with or without crusting

  • Cloudy, blurry vision

  • Faded colors

  • Headlights, lamps, or sunlight being too bright

  • Halos around lights

  • Poor night vision

  • Double vision (diplopia)

  • Loss of peripheral vision

  • Exophthalmos: bulging of eye anteriorly out of orbit

    Strabismus: both eyes do not focus on an object simultaneously, but either eye can focus alone

    The nurse should document the patient’s report of:

    • Trauma that can cause complete or partial dislocation of the eye

    The nurse should document the patient’s report of:

    • Poor vision

    • Sudden onset of double vision

    • Report of eye deviation

Documentation of Medical, Surgical, Family, and Personal/Social History

  • Employment risk: exposure to fumes, chemicals, particulates

  • Stress and coping mechanisms

  • Injury risk

  • Nutrition: excessive sugar

  • Use of alcohol, recreational drugs

  • Tobacco use (pack-year history), type of tobacco (cigarettes, chewing tobacco, snuff)

  • Sports played, new activities, use of protective eyewear

  • Corrective lenses – glasses, contacts

  • Trauma

  • Eye surgery

  • Chronic illness that can affect vision

    • Hypertension

    • Diabetes

    • Glaucoma

    • Inflammatory bowel disease

    • Thyroid dysfunction

    • Autoimmune disease

    • HIV

  • Retinoblastoma

  • Glaucoma

  • Color blindness

  • Nearsightedness, farsightedness

  • Strabismus

  • Amblyopia

Objective Data

  • Eyelids (loose, wrinkled)

  • Quality of the eyes (sunken, protruding)

  • Discharge

  • Eye movement

  • Ocular pressure

  • Hemorrhaging

  • Exophthalmos

    Strabismus

    Cataracts

    Glaucoma

    • Apparent eye protrusion

    • Lids do not reach iris

    • Measurement of degree of exophthalmos performed using exophthalmometer

    • Eye will not move in the direction controlled by affected muscle

    • Abnormal cover-uncover test result

    • Cloudy lens, may be obvious without equipment

    • Optic nerve damage, clearly seen during dilated eye examination

    • Characteristic cupping of optic nerve

    • Visual field test showing loss of peripheral vision

Key Notes

• The eyes carry visual data that are crucial for survival, education, and pleasure. More than half of our neocortex is involved with processing visual information.

• The external anatomy of the eye includes many structures. Each eye is protected by the bony orbital cavity surrounded with a cushion of fat.

• The eyelids further protect the eye from injury, strong light, and dust. The upper eyelid is larger and more mobile. Eyelashes curve outward from the lid margin to filter out dust and dirt. When closed, the lid margins approximate completely.

• The canthus is the corner of the eye, where the lids meet. The caruncle (a small fleshy mass containing sebaceous glands) is located at the inner canthus. A stripe of connective tissue, the tarsal plate, gives shape to the upper lid. The tarsal plates contain Meibomian glands, which secrete an oily lubricant onto the lids.

• The conjunctiva, a thin mucous membrane, is a transparent protective covering of the exposed part of the eye. The lacrimal apparatus provides constant irrigation. Tears drain into the puncta, visible on the upper and lower lids at the inner canthus.

• Six muscles attach the eyeball to its orbit and serve to direct our eyes to points of our interest: the superior, inferior, lateral, and medial rectus muscles and the superior and inferior oblique muscles. The movements of the extraocular muscles are stimulated by cranial nerves III, IV, and VI.

• The internal anatomy of the eye also includes many structures. The eye has three concentric coats or layers.

  • The outer layer is the sclera, a tough, fibrous protective, white covering that is continuous anteriorly with the smooth, transparent cornea. The cornea, which is part of the refracting media of the eye, covers the iris and pupil.

  • The middle layer is the choroid, which has dark pigmentation to prevent light from reflecting internally and is heavily vascularized to deliver blood to the retina. The choroid is continuous with the ciliary body and the iris. The ciliary body controls the thickness of the lens. The iris serves as a diaphragm, varying the opening at its center. Its muscle fibers contract and dilate the pupil, controlling how much light enters the retina.

  • The inner layer is the retina, which is the visual receptive layer of the eye. In the retina, light waves are changed into nerve impulses. The area of sharpest and keenest vision is the fovea centralis. The macula, a slightly darker pigmented region surrounding this area, transduces light from the center of the visual field.

• Visual reflexes include the pupillary light reflex, fixation, and accommodation.

  • The pupillary light reflex is the normal constriction of the pupils when bright light shines on the retina. Should be direct and consensual.

  • Fixation is a reflex direction of the eye toward an object attracting a person’s attention.

  • Accommodation is the adjustment of the eye for near vision. It is accomplished by ciliary muscle movement.

• The eyes undergo age-related changes.

  • At birth, eye function is limited. Peripheral vision is intact in newborns. The macula is absent at birth but is mature by age 8 months. Eye movement is poorly coordinated but matures by age 3 to 4 months. The eyeball reaches adult size by age 8.

  • With aging, lacrimal gland involution causes decreased tear production and dry, burning eyes. Pupil size decreases and the lens loses elasticity, causing presbyopia. The transparent fibers of the lens begin to thicken and yellow, resulting in cataract. Visual acuity may diminish gradually after age 50. In older adults, the four most common causes of decreased visual functioning are cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy.

• Culturally based variability exists in the color of the iris and retinal pigmentation, with darker irises having darker retinas behind them.

• Visual impairment is not being able to see letters on the line 20/50 or below on the eye chart. Racial disparities exist among major eye diseases and in visual impairment.

• Visual screening in children is crucial to detect strabismus and amblyopia. This section presents critical points about subjective and objective assessments of the eyes.

• To obtain subjective data, ask questions that investigate these topics:

  • Vision difficulty, including decreased acuity, blurring, and blind spots

  • Eye pain, burning or itching

  • Strabismus or diplopia

  • Redness or swelling

  • Watering or discharge

  • A history of ocular problems

  • Glaucoma

  • Use of glasses or contact lenses

  • Patient-centered care

  • Medications, systemic or topical

  • History of smoking

  • Vision loss

  • Additional history for infants and children should include vaginal infections in the mother at time of delivery, developmental milestones of vision noted by the parent, routine vision testing at school, and awareness of safety measures to protect the child’s eyes from trauma.

  • Aging adults should be asked about visual difficulty with driving or night vision, glaucoma testing, history of cataracts, dry or burning eyes, and decrease in usual activities.

• To obtain objective data, first test central visual acuity with a Snellen or other eye chart. For those over age 40 or who have difficulty reading, also test near vision.

  • Next, assess visual fields for loss of peripheral vision using the confrontation test: Stand arm’s length away and eyes length. Pt covers one eye; you cover same eye. Stare at each other’s nose and move finger into field of vision, you and patient should see finger at the same time.

  • Continue by observing extraocular muscle function. To do this, assess the corneal light reflex using the Hirschberg test (Used to see if pt has strabismus. Pt looks straight, Light 12 in away into pt eye. Light should be centered in both eyes). Also perform the diagnostic positions test, which is known as the six cardinal positions of gaze. Note any nystagmus.

  • Then inspect external eye structures. After a general inspection, specifically assess the eyebrows, eyelids and lashes, eyeball alignment, conjunctiva and sclera, upper lid eversion, and lacrimal apparatus.

  • Move on to inspect anterior eyeball structures. Observe the cornea and lens. Assess the iris and pupil, particularly noting their size, shape, and equality; the pupillary light reflex; and accommodation.

  • Finally, inspect the ocular fundus, or the internal surface of the retina, using an ophthalmoscope.

  • Observe the optic disc, noting its color, shape, and margins.

  • Estimate the cup-disc ratio.

  • Inspect the retinal vessels, assessing their number, color, caliber, and arteriovenous crossings. Estimate the artery-vein ratio, and check for tortuosity and pulsations.

  • Evaluate the color and integrity of the general background.

  • Inspect the macula last because it may cause watering, discomfort, and pupil constriction.

  • Adapt your examination techniques based on the patient’s developmental status. For example, use age-appropriate tools to assess visual acuity, such as a picture chart or Snellen E chart for a child, and color vision. Also adjust your expected findings based on the patient’s age.

  • The older adult’s central acuity and peripheral vision may be diminished. Vision impairment in the elderly is a leading cause of falls.

• When assessing the eyes, incorporate health promotion concepts. Keep in mind, for instance, that glaucoma is the leading cause of preventable blindness in the United States. Encourage early screenings for glaucoma

Class Notes

External Anatomy

  • Bony orbital cavity surrounded by cushion of fat protects eye

  • Palpebral fissure: opening between eyelids

  • Limbus: forms border between sclera and cornea

    • Canthus: upper and lower lids meet in corner of the eye.

      • Lateral and medial

      • Medial canthus holds the caruncle which is the fleshy part in corner of eye that moisturizes eyes and protects from bacteria

  • Tarsal plates

    • Meibomian glands

  • Conjunctiva: covers sclera and underside of upper and lower eyelids. Lubricants eye, secretes mucous and tears, protective barrier.

  • Cornea

  • Lacrima apparatus: lacrimal glands excrete tears

  • Extraocular muscles are innervated by cranial nerves III, IV, and VI. They hold eyes symmetrical and help eyes move at same time

    • Superior rectus (III)

    • Inferior rectus (III)

    • Lateral rectus (VI)

    • Medial rectus (III)

    • Superior Oblique (IV)

    • Inferior oblique (III)

Internal Anatomy

  • Eyes: Sphere of three concentric coats

  • Outer fibrous sclera

    • Sclera: Very limited blood vessels. Maintain shape of eye. Protects from external trauma.

    • Cornea: Protective. Allows lights in, focuses retina. Bends light to focus objects on inner retina. Must remain clear. Contains nociceptive cells (pain)

  • Middle Vascular Choroid:

    • Choroid: provide nourishment, very vascular

    • Iris: Color tissue. Use muscles to change size of pupil

    • Pupil: Determines how much light comes through. Opening at center of iris. Round, equal, black, very reactive to light. Normally 3-5 cm in size.

    • Lens: Size changes with focus. Behind iris. Clear. Refract light onto pupil. Elastic. Bulges to focus near and flattens when looking far.

    • Chambers act as boundaries

      • Anterior: Aqueous humor. Space between cornea and iris. Thin fluid contains vitamins and proteins. Aids in eye shape and light refraction. Small amount of fluid enters and exits constantly.

      • Posterior

      • Vitreous: Largest chamber, gel like vitreous humor, shock receptor maintains shape.

  • Inner Nervous Retina

    • Retina

    • Optic Disc: Circular area inside the back of the eye. Entry point for major blood vessels. Edema is papilledema (due to increased cranial pressure from CSF)

    • Optic Nerve: Responsible for carrying visual images to the brain

    • Macula: Center of retina. Central vision.

    • Fovea Centralis: Area of sharpest vision

Visual Pathways and Visual Fields: Pathway connects eyes to brain

  • Crossing of fibers at optic chiasm:

    • Left vision: Everything on the left.

    • Right Vision: Everything on the right

    • Optic Chiasm: Some visual signals will pass to other side. If there is damage before optic chiasm, you lose vision in one eye. If there is damage after the optic chiasms, vision is lost in both eyes.

  • Visual Reflexes:

    • Pupillary Light Reflexes: No conscious control.

      • Direct: When one eye is exposed to bright light and it constricts

      • Consensual: When light is shined in one eye, both eyes constrict

    • Fixation Reflex: Maintaining fixed visual gaze on an object. Foiba centralis. Extra ocular muscle helps maintain fixation. Can be impacted by external effects

    • Accommodation Reflex:

      • Convergence: Happens automatically (Like looking at far object and changed to near object)

  • Developmental Considerations:

    • Infants and Children:

      • Peripheral Vision: Intact but lens is spherical

      • Macula: Absent but matures at 8 months

      • Binocular Vision: 3-4 months old and can fixate Reaches adult size at 8 years

    • Aging Adult: Loss of skin elasticity. Lose fat tissue around orbit, muscles atrophy, pupil size changes, lens change and thickens, more rigid, and can’t accommodate for near vision. Presbyopia after age 40. Visual acuity decreases at 50. Difficulty adapting to the dark which impairs night driving and increases risk of falls.