Eye Anatomy Quiz

Light Transmission and Refraction

• Light rays are refracted through the transparent media (cornea, aqueous humor, lens, and vitreous body) and strike the retina
• The retina transforms the light stimulus into nerve impulses that are conducted through the optic nerve and the optic tract to the visual cortex of the occipital lobe

Visual Reflex

• Light reaction: occurs when a person shifts gaze from a far object to a near one and the pupils constrict
• Near reaction: occurs when a person shifts gaze from a far object to a near one and the pupils constrict

Developmental Considerations

• Peripheral vision is intact in the newborn infant
• Macula is absent at birth but develops by 4 months and is mature by 8 months
• Most babies (80%) are born farsighted; this gradually decreases after 7 to 8 years of age
• Eyeball reaches adult size by 8 years
• The lens is nearly spherical at birth, growing flatter throughout life

Gross Examination of the Eye and Its Adnexae

Cornea and Lens

• Inspect the cornea of each eye for opacities and note any opacities in the lens that may be visible through the pupil
• Opacities of the lenses visible through the pupil; most common in old age

Iris

• The iris normally appears flat, with a round regular shape and even coloration
• Shadow sign: a crescentic shadow on the medial side of the iris indicates acute angle-closure glaucoma

Pupils

• Inspect the size, shape, and symmetry of each pupil
• Pupil size decreases with age
• Lens loses elasticity, becoming hard and glasslike with presbyopia

Aging Adult

• Pupil size decreases
• Lens loses elasticity, becoming hard and glasslike
• Presbyopia: decreased ability of the lens to change shape to accommodate for near vision
• Cataract: clouding of the crystalline lens
• Glaucoma: optic nerve neuropathy characterized by loss of peripheral vision
• Macular degeneration: loss of central vision caused by yellow deposits and neovascularization in the macula
• Diabetic neuropathy: vision impairment with difficulty driving, reading, managing diabetes treatment, and other self-care

Health History: Vision Difficulty

• Is the difficulty during close work or at distances?
• Is there blurred vision?
• Are there any blind spots?
• Did the difficulty come on suddenly or progress slowly?
• Is the blurring of the entire field of vision or only parts of it?

Internal Anatomy

• Fundus: posterior part of the eye seen through an ophthalmoscope
• Optic disc: area in which fibers from the retina converge to form the optic nerve
• Physiologic cup: smaller circular area inside the disc where the blood vessels exit and enter
• Retinal vessels: paired artery and vein extending to each quadrant, growing progressively smaller as they reach the periphery
• Macula: receives and transduces light from the center of the visual field
• Fovea centralis: area of sharpest and keenest vision

Test your knowledge of the internal anatomy of the human eye, including the pupil, lens, retina, and other structures. Identify the functions of each part and how they work together to facilitate vision. From the fundus to the optic disc, challenge yourself to learn more about the amazing human eye!