Eyes

Question 1

Sclera

Answer 1

: Tough, protective white covering continuous with the cornea, which bends light rays to focus on the retina.

Question 2

Corne

Answer 2

a: Transparent, sensitive to touch; contact triggers the corneal reflex:
o Afferent nerve: Trigeminal (CN V).
o Efferent nerve: Facial (CN VII).

Question 3

Conjunctiva

Answer 3

: Transparent protective covering with two parts:
o Palpebral: Lines the eyelids.
o Bulbar: Covers the eyeball, merging with the cornea at the limbus.

Question 4

Iris

Answer 4

Acts as a diaphragm, controlling pupil size for light adjustment.

Question 5

Pupil

Answer 5

:
o Round, regular.
o Parasympathetic stimulation (CN III): Constriction.
o Sympathetic stimulation: Dilation.

Question 6

Lens

Answer 6

Transparent disc behind the pupil; adjusts thickness for near (bulging) or far (flattening) focus.

Question 7

Retin

Answer 7

a: Visual receptor layer, converts light into nerve impulses.
o Structures visible via ophthalmoscope: Optic disc, retinal vessels, background, macula

Question 8

Direct reflex

Answer 8

: Constriction of exposed pupil.
o Consensual reflex: Constriction of opposite pupil due to synapse at the brain’s optic chiasm.
o Afferent nerve: Optic (CN II).
o Efferent nerve: Oculomotor (CN III).

Question 9

Fixation

Answer 9

: Rapid eye movements focus on an object of attention. Impaired by fatigue, medications, or alcohol.

Question 10

Accommodation

Answer 10

: Pupillary constriction and lens curvature adjustment for near vision.

Question 11

Extraocular Muscles

Answer 11

• Cranial Nerves Controlling Eye Movement:
  o CN VI (Abducens): Lateral rectus (abducts eye).
  o CN IV (Trochlear): Superior oblique (downward and inward movement).
  o CN III (Oculomotor): All other muscles (superior, inferior, medial rectus; inferior oblique).

Question 12

Common Eye Disorders

Answer 12

• Age-Related Macular Degeneration (AMD):
  o Breakdown of macular cells; loss of central vision.
  o Leading cause of blindness in Canada; higher risk for women.
• Cataracts:
  o Lens opacity from protein clumping.
  o Common in older adults (>70 years); risk factors include diabetes and steroid use.
• Glaucoma:
  o Increased intraocular pressure, optic nerve damage, peripheral vision loss.
  o Chronic open-angle glaucoma is the most common form.
• Diabetic Retinopathy:
  o Leading cause of vision loss in younger populations.
  o Regular screening is essential for diabetic patients.

Question 13

Eye Examination Steps

Answer 13

1. Visual Acuity:
   o Snellen chart for distance vision.
   o Near vision test for patients >40 years.
2. Visual Fields:
   o Confrontation test to assess peripheral vision.
3. Extraocular Muscle Function:
   o Corneal light reflex (Hirschberg’s test).
   o Cover-uncover test.
   o Diagnostic positions test to evaluate muscle strength.
4. External Structures:
   o Inspect general appearance, eyebrows, eyelids, lashes, and eyeball alignment.
5. Anterior Structures:
   o Check cornea, lens, iris, and pupils for size, shape, reflexes, and accommodation.

Question 14

Social Determinants of Health and Vision

Answer 14

• Many Canadians lack access to affordable vision care.
• Limited provincial healthcare coverage for routine eye exams and corrective lenses.
• High-risk populations: People with diabetes, Indigenous communities, or African descent (higher glaucoma rates).
• Nurses should refer low-income individuals to free or reduced-cost services.

Question 15

. Test Visual Acuity

Answer 15

• Snellen Eye Chart:
  o Measures distance vision.
  o Normal result: 20/20.
  o Numerator = distance from chart; denominator = distance normal eye sees that line.
  o If vision is poorer than 20/30, refer to an ophthalmologist.
• Near Vision Test (for patients >40 or with difficulty reading):
  o Use Jaeger card, held 14 inches from eyes.
  o Normal result: 14/14.
  o Moving the card farther away indicates presbyopia (aging-related reduced accommodation).

Question 16

Test Visual Fields

Answer 16

• Confrontation Test:
  o Compares patient’s peripheral vision to examiner’s.
  o Normal angles: 50° upward, 90° temporal, 70° downward, 60° nasal.
  o Loss of field may indicate glaucoma or retinal disorders.

Question 17

Inspect Extraocular Muscle Function

Answer 17

• Corneal Light Reflex (Hirschberg’s Test):
  o Shine light; reflection should be symmetrical on both corneas.
  o Asymmetry indicates muscle weakness or strabismus.
• Cover-Uncover Test:
  o Detects misalignment.
  o Normal: Uncovered eye remains fixed; no movement of covered eye when uncovered.
  o Misalignment suggests phoria (mild weakness) or tropia (severe misalignment).
• Diagnostic Positions Test:
  o Move target through six cardinal positions of gaze.
  o Normal: Smooth, parallel movement.
  o Abnormal: Nystagmus (oscillating movements) or muscle weakness.

Question 18

Inspect External Eye Structures

Answer 18

• General:
  o Observe facial expression, mobility, and ability to avoid obstacles.
• Eyebrows:
  o Symmetrical movement; no scaling or lesions.
  o Uneven movement may indicate nerve damage.
• Eyelids and Lashes:
  o Lid closure should be complete; lashes evenly distributed.
  o Abnormalities: Ptosis (drooping), ectropion (outward rolling), or entropion (inward rolling).
• Eyeball Alignment:
  o Aligned in socket; no protrusion (exophthalmos) or sunken appearance (enophthalmos).
• Conjunctiva and Sclera:
  o Conjunctiva should be clear; sclera white or slightly grey-blue in darker-skinned individuals.
  o Abnormal: Redness (conjunctivitis), jaundice (yellow sclera).
• Lacrimal Apparatus:
  o No swelling or redness; tear drainage system intact.
  o Blockage indicated by excessive tearing or fluid regurgitation.

Question 19

. Inspect Anterior Eyeball Structures

Answer 19

• Cornea and Lens:
  o Smooth, clear surface with no cloudiness.
  o Abnormalities: Corneal abrasion or cataracts (lens opacity).
• Iris and Pupil:
  o Iris: Flat, round, evenly colored.
  o Pupils: Equal, round, reactive to light and accommodation (PERRLA).
  o Normal size: 3–5 mm.
  o Abnormalities: Unequal pupils (anisocoria), dilated pupils (mydriasis), or constricted pupils (miosis).
• Pupillary Light Reflex:
  o Direct: Constriction of illuminated pupil.
  o Consensual: Constriction of opposite pupil.
  o Absent reflex suggests CNS injury.
• Accommodation:
  o Normal: Pupillary constriction and inward movement of eyes for near focus.