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Questions and Answers
Which of the following eye responses would be considered typical for an infant?
Which of the following eye responses would be considered typical for an infant?
Why is the Snellen eye chart not an ideal method for testing the vision of a baby like Molly?
Why is the Snellen eye chart not an ideal method for testing the vision of a baby like Molly?
Based on the information provided, what is the probability that two heterozygous parents would have a child with Leber Congenital Amaurosis (LCA)?
Based on the information provided, what is the probability that two heterozygous parents would have a child with Leber Congenital Amaurosis (LCA)?
What is the primary function of the eyelashes?
What is the primary function of the eyelashes?
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Which of the following best describes the function of the conjunctiva?
Which of the following best describes the function of the conjunctiva?
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Which structure is responsible for producing tears?
Which structure is responsible for producing tears?
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The 'cooperative eye hypothesis' suggests that the contrast between the white sclera and the colored iris is for what purpose?
The 'cooperative eye hypothesis' suggests that the contrast between the white sclera and the colored iris is for what purpose?
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What part of the eye is directly involved in transmitting visual information to the brain?
What part of the eye is directly involved in transmitting visual information to the brain?
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What condition is characterized by a thinning of the cornea and a cone-like bulge?
What condition is characterized by a thinning of the cornea and a cone-like bulge?
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What is a common cause of optic neuritis?
What is a common cause of optic neuritis?
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Study Notes
Chapter 14 - Sensory Perception (EYE)
- Molly's mother noticed vision problems in Molly as a baby.
- While breastfeeding, Molly fixated on room lights.
- Molly frequently rubbed and pressed her eyes.
- Molly underwent vision tests.
Response to Light
- Infants typically blink in response to bright light.
- Molly did not respond to bright light.
Pupil Response
- The pupil is an opening in the eye allowing light.
- Pupils dilate in darkness and constrict in bright light.
- Molly's pupils were slow to react to bright light.
Ability to Follow a Target
- Infants typically follow interesting objects.
- Molly could not track objects.
Ability to Navigate Obstacles
- Molly frequently bumped into objects and tripped.
Leber Congenital Amaurosis (LCA)
- Molly was diagnosed with LCA.
- LCA is a genetic condition.
- Molly inherited two defective copies of the RPE65 gene.
- Each parent carried one defective copy (recessive).
Eye Structure and Accessory Organs
- Eyelids: Covers and protects the eye; thin skin
- Eyelashes: Fine hairs that protect from dust and debris.
- Trichiasis: Inversion of eyelashes, can irritate eye.
- Conjunctiva: Covering around eye and under eyelids.
- Pink Eye (Conjunctivitis): Inflammation of conjunctiva typically caused by bacteria (highly contagious).
- Extrinsic Eye Muscles: Move the eye, e.g., Superior rectus, Lateral rectus, Inferior oblique
Lacrimal Glands
- Produce tears.
- Tears drain into the nasal cavity via lacrimal duct.
- Tears moisten and lubricate the eye surface.
- Tears contain enzymes that kill bacteria.
Outer Tunic of the Eye
- Cornea: Transparent dome-shaped part of the eye focusing light.
- Cornea transplants can replace damaged or diseased corneas.
- Organ donors can donate corneas if they are consented.
- Sclera: Continuation of cornea, white part of the eye
- Cooperate Eye Hypothesis: Proposes that eye appearance evolved for easier human gaze communication.
Optic Nerve
- Exits at the optic disk.
- Transmits information from the eye to the occipital lobe of the brain.
- During Prohibition, methanol poisoning often damaged optic nerve.
Middle Tunic of the Eye
- Choroid: Contains blood vessels.
- Ciliary Body: Holds the lens in place.
- Lens: Focusing.
- Iris: Colored portion of the eye.
- Pupil: Opening for light to enter the eye.
- Aqueous Humor: Liquid surrounding the lens.
Anatomy of the Eye
- Clear anatomical details, including important parts like the cornea and sclera, retina and optic nerve, are visible.
Eye Color
- Melanin adds color to eyes, hair, and skin.
- Caucasian babies often have bluish eyes at birth
- Melanin levels in eyes increase with sunlight exposure that change eye color.
- Brown is the most common eye color globally.
- Heterochromia means one eye is a different color.
Pupils
- Pupils dilate or constrict to adjust light entering the eye.
- Fun fact: Pupils often dilate when looking at someone you love or hate
What Causes Red-Eye?
- Bright camera flash reflects off the retina causing that red-color.
- Advanced cameras often use a dual-flash technique to reduce red-eye.
Inner Tunic
- Retina: Visual receptor cells, located behind the choroid.
- Fovea Centralis (Macula): Region with the sharpest vision.
- Optic Disc: Where optic nerve exits the eye (blind spot).
- Vitreous Humor: Supports eye's internal structures, a fluid within the eye.
The Retina
- Contains photoreceptors, sensors sensitive to light.
- In LCA, RPE65 protein expression causes retinal cells death.
Rods and Cones
- Rods - monochromatic (black and white) vision
- Cones - color vision.
Refraction of Sunlight
- Rainbows occur due to light separating into its constituent colors.
- Human's eyes contain three different colors sensitive cone cells, red green blue - Dogs only have yellow and blue.
Blind Spots (Optic Disk)
- The area where the optic nerve and blood vessels leave the eye is the blind spot.
- The blind spot is a region that has no photoreceptors.
- This lack of photoreceptors results in the absence of vision in this area..
Problems with the Eyes
- Cataracts: Clouding of the lens.
- Treatment: Lens removal & intraocular lens implantation.
- Aniridia: Born without an iris (colored part of the eye).
Eye Problems
- Onchocerciasis (River Blindness): Parasitic worm disease causing eye damage and blindness
- Color Blindness: Genetic trait affecting boys more than girls. Gene location: X-chromosome
Float and Retinal Detachment
- Floaters: Clumps of vitreous substance casting shadows within the eye.
- Retinal Detachment: Retina detachment occurs pulling away of retina.
- Treatment: Urgent medical attention
Glaucoma
- Excessive vitreous humor pressure damages the optic nerve potentially leading to blindness.
- Treatment: Medication Management.
Refractive Errors
- Hyperopia (Farsightedness): Light focus behind retina, distant vision is clearer than near vision.
- Myopia (Nearsightedness): Light focus in front of retina, near vision clearer than distant vision.
- Astigmatism: Irregular shape of the cornea causing blurry vision.
Surgery Options
- LASIK eye surgery: Procedure to correct refractive errors.
Gene Therapy
- Gene therapy may be an option for certain conditions, including Leber Amaurosis.
- FDA approved gene therapy for Leber Amaurosis in 2010.
Retinal Gene Therapy
- Procedure involving injecting a new gene to treat retinal disorders.
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Description
Explore the key concepts of sensory perception with a focus on vision, as highlighted in Chapter 14. Learn about the developmental milestones in infant vision through Molly's experiences, including difficulties in response to light and tracking. Understand the implications of genetic conditions like Leber Congenital Amaurosis (LCA) on visual capabilities.
