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Questions and Answers

What is homeostasis?

Homeostasis is the tendency towards a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes.

What are the consequences of interrupted homeostasis in the eye?

  • Visual impairment (correct)
  • Changes in color vision (correct)
  • Age-related macular degeneration (correct)
  • Peripheral vision loss (correct)

    • Accommodation is the process of making things _____

    clear

    Cornea provides more than two-thirds of the total refractive power of the eye.

    <p>True</p> Signup and view all the answers

    What prevents evaporation and helps in fast dissolving of oxygen when it gets to the lipid layer?

    <p>Lipid layer</p> Signup and view all the answers

    Is the cornea more acidic when in contact with contact lenses?

    <p>True</p> Signup and view all the answers

    What happens when there is a lack of oxygen in the cornea?

    <p>Interruption of homeostasis</p> Signup and view all the answers

    Higher the DK/t value, the more _____ can be transmitted to the eye.

    <p>oxygen</p> Signup and view all the answers

    Match the following aspects of vision with what they are not measured by:

    <p>Colour vision = measured by the chart Sensitivity to light = measured by the chart Form perception = not measured by the chart Peripheral vision = not measured by the chart</p> Signup and view all the answers

    What is the primary function of the cornea in the human eye?

    <p>To provide more than two-thirds of the total refractive power</p> Signup and view all the answers

    What is measured by the chart in a clinical setting?

    <p>Visual acuity</p> Signup and view all the answers

    What is the relationship between DK/t value and oxygen transmission?

    <p>Higher DK/t value, the more oxygen is transmitted</p> Signup and view all the answers

    What is the term for the ability of the eye to perceive shapes and forms?

    <p>Form perception</p> Signup and view all the answers

    What is not measured by the chart in a clinical setting?

    <p>Color vision</p> Signup and view all the answers

    What is the term for the ability of the eye to perceive light?

    <p>Light perception</p> Signup and view all the answers

    What is the role of anatomy in understanding visual perception?

    <p>It helps to understand the structure of the eye</p> Signup and view all the answers

    What is the benefit of evidence-based research in clinical care?

    <p>It helps to transform clinical care</p> Signup and view all the answers

    What is the purpose of the homeostatic reflex centre for the visual system?

    <p>To maintain a stable environment for the visual pathway</p> Signup and view all the answers

    What is the result of accommodation in the visual system?

    <p>Clearer vision of objects</p> Signup and view all the answers

    What is the relationship between convergence and accommodation?

    <p>Accommodation causes convergence</p> Signup and view all the answers

    What happens when the visual system is unable to maintain homeostasis?

    <p>The visual system becomes unstable</p> Signup and view all the answers

    What is the main function of the cornea?

    <p>To refract light and provide more than two-thirds of the total refractive power of the eye</p> Signup and view all the answers

    What is the role of the homeostatic reflex centre in the visual pathway?

    <p>To maintain a stable environment for the visual pathway</p> Signup and view all the answers

    What is the relationship between the homeostatic reflex centre and clear vision?

    <p>The homeostatic reflex centre is necessary for clear vision</p> Signup and view all the answers

    What is the primary function of homeostasis in the human body?

    <p>To maintain internal stability in response to changing conditions</p> Signup and view all the answers

    What is the outcome of a stable visual pathway?

    <p>Clear vision</p> Signup and view all the answers

    Which of the following best describes the concept of homeostasis?

    <p>A tendency towards a relatively stable equilibrium</p> Signup and view all the answers

    What is the significance of homeostasis for proper eye function and health?

    <p>It is necessary for maintaining optimal vision</p> Signup and view all the answers

    What is an example of homeostasis in everyday life?

    <p>Maintaining a stable body temperature</p> Signup and view all the answers

    What is the importance of homeostasis in relation to the eye?

    <p>It is important for maintaining proper eye function and health</p> Signup and view all the answers

    What is the goal of homeostasis in the human body?

    <p>To maintain optimal physiological conditions</p> Signup and view all the answers

    What is the relationship between homeostasis and clear vision?

    <p>Homeostasis is necessary for maintaining clear vision</p> Signup and view all the answers

    What is the underlying basis of homeostasis in human physiology?

    <p>A self-regulating process</p> Signup and view all the answers

    In age-related macular degeneration, what is the characteristic of the new blood vessels that form?

    <p>They are leaky</p> Signup and view all the answers

    What is the body's response in age-related macular degeneration?

    <p>The body tries to compensate for the lack of nutrients by forming new vessels</p> Signup and view all the answers

    What is the result of the lack of oxygen and nutrients in the retina?

    <p>The retina starts to degenerate</p> Signup and view all the answers

    What is the significance of the new vessels in age-related macular degeneration?

    <p>They are a sign of disease progression</p> Signup and view all the answers

    What is the relationship between the new vessels and the retina in age-related macular degeneration?

    <p>The new vessels are a part of the retina</p> Signup and view all the answers

    What is the underlying cause of the formation of new vessels in age-related macular degeneration?

    <p>The body's response to a lack of oxygen and nutrients</p> Signup and view all the answers

    What is the primary role of the tear film in the human eye?

    <p>To prevent evaporation and keep the cornea moist</p> Signup and view all the answers

    Why is the cornea considered an avascular tissue?

    <p>Because it does not have a blood supply</p> Signup and view all the answers

    What is the main function of the lipid layer in the tear film?

    <p>To regulate tear evaporation</p> Signup and view all the answers

    What is the consequence of a lack of oxygen in the cornea?

    <p>Impaired cellular function and potentially corneal damage</p> Signup and view all the answers

    What is the role of oxygen in the lipid layer of the tear film?

    <p>To dissolve and facilitate the transmission of oxygen to the cornea</p> Signup and view all the answers

    What is the relationship between the cornea and the tear film?

    <p>The tear film is essential for maintaining the health and function of the cornea</p> Signup and view all the answers

    What is the term for the ability of the eye to perceive shapes and forms?

    <p>Form perception</p> Signup and view all the answers

    Why is the understanding of ocular anatomy and physiology important in clinical care?

    <p>To provide evidence-based care for patients with eye disorders</p> Signup and view all the answers

    Why do systemic drugs not easily reach the eye?

    <p>Because the eye has a blood-ocular barrier</p> Signup and view all the answers

    What is the main challenge in delivering systemic medications to the eye?

    <p>Systemic medications cannot cross the blood-ocular barrier</p> Signup and view all the answers

    What is the advantage of injecting medications locally in the sub-retina?

    <p>It bypasses the blood-ocular barrier</p> Signup and view all the answers

    Why is it difficult to deliver systemic medications to the retina?

    <p>Because the blood-ocular barrier prevents medications from reaching the retina</p> Signup and view all the answers

    What is the primary reason for using local administration of medications in the eye?

    <p>To bypass the blood-ocular barrier</p> Signup and view all the answers

    What is the importance of understanding the relationship between systemic medications and ocular effects?

    <p>To prevent adverse ocular effects of systemic medications</p> Signup and view all the answers

    Why is it important to explore the clinical manifestations of amiodarone on the cornea?

    <p>To identify potential adverse ocular effects of amiodarone</p> Signup and view all the answers

    What is the significance of discussing the clinical manifestations of plaquenil on the retina?

    <p>To identify potential adverse retinal effects of plaquenil</p> Signup and view all the answers

    What is the primary function of amiodarone?

    <p>To treat irregular heartbeats</p> Signup and view all the answers

    What is Cornea verticillata also known as?

    <p>Vortex keratopathy</p> Signup and view all the answers

    What is the result of taking amiodarone medication?

    <p>Increased time before a heart cell can contract again</p> Signup and view all the answers

    What is the indication for amiodarone medication?

    <p>To treat irregular heartbeats</p> Signup and view all the answers

    What is the effect of amiodarone on the cornea?

    <p>It causes Cornea verticillata</p> Signup and view all the answers

    When was amiodarone first introduced?

    <p>1961</p> Signup and view all the answers

    What is Plaquenil primarily used to treat?

    <p>All of the above</p> Signup and view all the answers

    What is a common side effect of Plaquenil?

    <p>All of the above</p> Signup and view all the answers

    What is Bullseye Maculopathy associated with?

    <p>Plaquenil</p> Signup and view all the answers

    What is the effect of Plaquenil on the eye?

    <p>Ocular toxicity</p> Signup and view all the answers

    What is the purpose of electro-oculography?

    <p>To measure the electrical activity of the retina</p> Signup and view all the answers

    What does the visual field test measure?

    <p>The visual field of the eye</p> Signup and view all the answers

    What is the symptom of advanced Plaquenil toxicity?

    <p>All of the above</p> Signup and view all the answers

    What is the location of the lesion in Bullseye Maculopathy?

    <p>Macula</p> Signup and view all the answers

    What is Bull's Eye maculopathy?

    <p>A sign of advanced Plaquenil toxicity</p> Signup and view all the answers

    What is the impact of Plaquenil on the retina?

    <p>It causes retinal toxicity</p> Signup and view all the answers

    What is the significance of the FP field in retinal investigations?

    <p>It measures the visual field of the eye</p> Signup and view all the answers

    What is the purpose of retinal investigations?

    <p>To diagnose retinal diseases such as Bullseye Maculopathy</p> Signup and view all the answers

    What is the relationship between the duration of Plaquenil use and retinal toxicity?

    <p>Longer duration of use increases the risk of toxicity</p> Signup and view all the answers

    What is the outcome of advanced Plaquenil toxicity?

    <p>Irreversible vision loss</p> Signup and view all the answers

    What are some common ways amiodarone can be administered?

    <p>Orally, intravenously, and intraosseously</p> Signup and view all the answers

    What are some common side effects of amiodarone?

    <p>Feeling tired, tremor, nausea, and constipation</p> Signup and view all the answers

    What is a characteristic of amiodarone?

    <p>Long half-life</p> Signup and view all the answers

    What is vortex keratopathy?

    <p>A condition affecting the cornea</p> Signup and view all the answers

    What happens to the medication amiodarone in the body?

    <p>It is taken up by lysosomes</p> Signup and view all the answers

    What is the effect of amiodarone on the cornea?

    <p>It causes vortex keratopathy</p> Signup and view all the answers

    What is the significance of the day numbers (39, 128, 194) in the context of amiodarone?

    <p>They represent the time course of vortex keratopathy</p> Signup and view all the answers

    What is the relationship between amiodarone and the cornea?

    <p>Amiodarone causes vortex keratopathy in the cornea</p> Signup and view all the answers

    What is the purpose of the hyaloid artery in the embryonic development of the eye?

    <p>To provide nutrients to the lens</p> Signup and view all the answers

    What is the remnant of the hyaloid artery that can be seen in the eye after birth?

    <p>Persistent hyaloid artery</p> Signup and view all the answers

    What is the tunica vasculosa lentis?

    <p>A network of blood vessels that supplies the lens</p> Signup and view all the answers

    What is the function of the Bergmeister papilla?

    <p>To allow for the regression of the hyaloid artery</p> Signup and view all the answers

    What is the Mittendorf dot?

    <p>A remnant of the hyaloid artery</p> Signup and view all the answers

    What is the result of the regression of the hyaloid artery?

    <p>The clearance of the vitreous humor</p> Signup and view all the answers

    What is the significance of the hyaloid artery in the development of the eye?

    <p>It supplies oxygen and nutrients to the lens</p> Signup and view all the answers

    What is the consequence of the failure of the hyaloid artery to regress?

    <p>The presence of a benign finding such as a Mittendorf dot</p> Signup and view all the answers

    What is the relationship between the hyaloid artery and the lens?

    <p>The hyaloid artery supplies oxygen and nutrients to the lens</p> Signup and view all the answers

    What is the significance of the tunica vasculosa lentis in the development of the eye?

    <p>It supplies oxygen and nutrients to the lens</p> Signup and view all the answers

    What is the effect of blockage in the central retina artery?

    <p>Loss of vision in one eye</p> Signup and view all the answers

    Which of the following is NOT an extraocular muscle?

    <p>Smooth muscle</p> Signup and view all the answers

    What is the function of the Four Recti muscles?

    <p>To rotate the eyeball</p> Signup and view all the answers

    What is the term for the inward turning of the eye?

    <p>Esophoria</p> Signup and view all the answers

    Which muscle is responsible for elevating the eyelid?

    <p>Levator palpebrae superioris</p> Signup and view all the answers

    What is the term for the outward turning of the eye?

    <p>Exophoria</p> Signup and view all the answers

    How many extraocular muscles are there?

    <p>7</p> Signup and view all the answers

    What is the term for normal eye alignment?

    <p>Orthophoria</p> Signup and view all the answers

    What is the primary function of the extraocular muscles?

    <p>To move the eyeball in its socket and avoid double vision</p> Signup and view all the answers

    What is the purpose of the six extraocular muscles working together?

    <p>To avoid double vision and maintain binocular vision</p> Signup and view all the answers

    Which of the following is NOT a function of the extraocular muscles?

    <p>To regulate the amount of light entering the eye</p> Signup and view all the answers

    What is the consequence of weak or damaged extraocular muscles?

    <p>Double vision</p> Signup and view all the answers

    How many extraocular muscles are responsible for moving the eyeball?

    <p>6</p> Signup and view all the answers

    What is the name of the nerve that carries visual information from the eye to the brain?

    <p>Optic nerve</p> Signup and view all the answers

    What is the primary muscle that moves an eye in a given direction?

    <p>Agonist</p> Signup and view all the answers

    Which muscle receives equal and simultaneous innervation according to Hering's law?

    <p>Yoke muscle</p> Signup and view all the answers

    What is the function of the superior rectus muscle?

    <p>Elevation</p> Signup and view all the answers

    What is the secondary action of the superior rectus muscle?

    <p>Incyclotorsion</p> Signup and view all the answers

    What is the function of the inferior oblique muscle?

    <p>Excyclotorsion</p> Signup and view all the answers

    What is the tertiary action of the superior oblique muscle?

    <p>Abduction</p> Signup and view all the answers

    What is the antagonist of the agonist muscle in the same eye?

    <p>Antagonist</p> Signup and view all the answers

    What is the synergist muscle in the same eye?

    <p>Synergist</p> Signup and view all the answers

    What is the term for the movement of the eye towards the nose?

    <p>Adduction</p> Signup and view all the answers

    What is the term for the movement of both eyes to the patient's right?

    <p>Dextroversion</p> Signup and view all the answers

    What is the term for the rotation of the upper vertical meridian towards the nose?

    <p>Incycloduction</p> Signup and view all the answers

    What is the term for the movement of both eyes upwards?

    <p>Supraversion</p> Signup and view all the answers

    What is the term for the movement of the eye away from the nose?

    <p>Abduction</p> Signup and view all the answers

    What is the term for the rotation of the upper vertical meridian away from the nose?

    <p>Excycloduction</p> Signup and view all the answers

    What is the term for the movement of both eyes to the patient's left?

    <p>Levoversion</p> Signup and view all the answers

    What is the term for the downward movement of both eyes?

    <p>Infraversion</p> Signup and view all the answers

    What is the primary function of the sympathetic nervous system in the eye?

    <p>To dilate the pupil</p> Signup and view all the answers

    Which nerve is responsible for the innervation of the medial rectus muscle?

    <p>Oculomotor nerve (inferior branch)</p> Signup and view all the answers

    What is the primary function of the short ciliary nerve?

    <p>To constrict the pupil</p> Signup and view all the answers

    Which vessel is responsible for the blood supply to the inner portion of the retina?

    <p>Central retinal artery</p> Signup and view all the answers

    What is the function of the superior oblique muscle?

    <p>Incyclotorsion and depression of the eye</p> Signup and view all the answers

    What is the primary function of the choroid?

    <p>To facilitate blood flow to the retina</p> Signup and view all the answers

    What is the function of the vortex vein?

    <p>To facilitate the drainage of the choroid</p> Signup and view all the answers

    What is the primary function of the inferior oblique muscle?

    <p>Excyclotorsion and elevation of the eye</p> Signup and view all the answers

    What is the function of the levator palpebrae superioris muscle?

    <p>To elevate and retract the upper eyelid</p> Signup and view all the answers

    Which nerve is responsible for the innervation of the inferior oblique muscle?

    <p>Oculomotor nerve (inferior branch)</p> Signup and view all the answers

    What is the primary function of the cornea in the human eye?

    <p>To refract light and provide about two-thirds of the total refractive power of the eye</p> Signup and view all the answers

    What is unique about the innervation of the cornea?

    <p>It is highly innervated and sensitive to pain</p> Signup and view all the answers

    What is the cellular composition of the epithelium of the cornea?

    <p>Made up of 3 cells</p> Signup and view all the answers

    What is the significance of the uvea in the eye?

    <p>It is involved in the regulation of the amount of light entering the eye</p> Signup and view all the answers

    What is the importance of understanding the anatomy of the cornea and uvea?

    <p>It is important for understanding visual perception and clinical care</p> Signup and view all the answers

    What is the relationship between the cornea and the tear film?

    <p>The tear film helps to prevent evaporation and promote oxygenation of the cornea</p> Signup and view all the answers

    Why is the understanding of ocular anatomy and physiology important in clinical care?

    <p>It is important for understanding the underlying causes of eye diseases and developing effective treatments</p> Signup and view all the answers

    What is the characteristic of the cornea that makes it an avascular tissue?

    <p>It lacks blood vessels</p> Signup and view all the answers

    What is the layer of the cornea that is produced naturally every 6-7 days?

    <p>Limbal stem cells</p> Signup and view all the answers

    What is the layer of the cornea that contains nerve trunks?

    <p>Mid stroma</p> Signup and view all the answers

    What is the term for the folds of the conjunctiva?

    <p>Palisades of Vogt</p> Signup and view all the answers

    What is the purpose of confocal microscopy imaging in the cornea?

    <p>To image the various layers of the cornea</p> Signup and view all the answers

    What is the primary advantage of Photorefractive Keratectomy (PRK) over LASIK?

    <p>It does not require a flap to be created</p> Signup and view all the answers

    What is the layer of the cornea that is closest to the aqueous humor?

    <p>Endothelium</p> Signup and view all the answers

    What is the shape of the cornea's curvature?

    <p>Steeper vertically</p> Signup and view all the answers

    In which part of the cornea can reshaping be done using a laser?

    <p>Stroma</p> Signup and view all the answers

    What is the name of the latest technology in Small Incision Lenticule Extraction (SMILE) procedures?

    <p>I SMILE</p> Signup and view all the answers

    What is the layer of the eye that is removed by mechanical means in PRK?

    <p>Corneal epithelium</p> Signup and view all the answers

    What is required for reshaping the cornea using a laser?

    <p>Thin cornea</p> Signup and view all the answers

    What is the layer of the cornea that contains nerve plexus?

    <p>Subbasal nerve plexus</p> Signup and view all the answers

    What is prescribed after LASIK surgery?

    <p>Antibiotic and steroid eye drops</p> Signup and view all the answers

    Which type of refractive surgery does not treat long-sighted vision?

    <p>I SMILE</p> Signup and view all the answers

    What is the term for the ridges at the limbus?

    <p>Limbal palisade ridges</p> Signup and view all the answers

    What is the term for the surgical procedure that involves creating a flap in the cornea?

    <p>Laser-Assisted In Situ Keratomileusis</p> Signup and view all the answers

    Why is the cornea reshaped during LASIK surgery?

    <p>To improve vision</p> Signup and view all the answers

    Which type of refractive surgery is also known as surface surgery?

    <p>PRK</p> Signup and view all the answers

    What is the purpose of reshaping the cornea?

    <p>To improve vision</p> Signup and view all the answers

    What is the result of reshaping the cornea?

    <p>Improved vision</p> Signup and view all the answers

    Why is it necessary to reshape the cornea?

    <p>To correct moderate refraction</p> Signup and view all the answers

    What is the benefit of reshaping the cornea?

    <p>Improved vision</p> Signup and view all the answers

    What is the primary role of the epithelium in corneal wound healing after PRK surgery?

    <p>To undergo mitosis and form a monolayer</p> Signup and view all the answers

    What is the importance of the interaction between epithelial cells and keratocytes in corneal wound healing?

    <p>It promotes the synthesis of collagen and proteoglycans</p> Signup and view all the answers

    What is the origin of the cells that participate in corneal wound healing?

    <p>Limbal stem cells</p> Signup and view all the answers

    What is the role of the stroma in corneal wound healing?

    <p>It synthesizes collagen and proteoglycans</p> Signup and view all the answers

    What is the significance of the limbus in corneal wound healing?

    <p>It is the source of stem cells that participate in wound healing</p> Signup and view all the answers

    What is the consequence of impaired epithelial cell migration in corneal wound healing?

    <p>Delayed wound healing</p> Signup and view all the answers

    What is the role of antibiotics in corneal refractive surgery?

    <p>To prevent infection</p> Signup and view all the answers

    What is the purpose of eye protection in corneal refractive surgery?

    <p>To protect the eye from mechanical injury</p> Signup and view all the answers

    Study Notes

    Anatomy of the Visual System

    • The visual system consists of the eye, optic nerve, and visual cortex.
    • The eye is a complex structure that detects light and converts it into electrical signals that are transmitted to the brain.

    Homeostasis and Clear Vision

    • Homeostasis is the ability of the body to maintain a stable internal environment despite changes in the external environment.
    • Homeostasis is important for proper eye function and health.
    • Definition: Homeostasis is the tendency towards a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes.
    • Example: Optimal temperature homeostasis is "not too hot, not too cold; just right."
    • Homeostasis is also important for blood flow, balance, and blood pressure.

    Homeostasis in the Eye

    • Age-related macular degeneration (AMD) is a condition that affects the macula, the part of the retina responsible for central vision.
    • There are two types of AMD: dry (non-exudative) and wet (exudative).
    • Wet AMD is less common but more severe and can lead to faster and more significant vision loss.
    • It occurs when abnormal blood vessels are fragile and leak blood and fluid, leading to bleeding and scarring of the retina.

    Homeostasis in the Visual Pathway

    • Homeostasis in the visual pathway is important for maintaining clear vision.
    • Disruptions to homeostasis can lead to conditions such as glaucoma, cataracts, and age-related macular degeneration.
    • Glaucoma can cause compression of the optic nerve, leading to loss of peripheral vision (bitemporal hemianopsia).
    • Visual acuity reduction, color vision changes, and other visual disturbances can also occur.

    Homeostasis of the Visual System

    • The homeostatic reflex center for the visual system is responsible for maintaining clear vision.
    • The components of the homeostatic reflex center include the Edinger Westphal nucleus, which is responsible for regulating pupil size and accommodation.
    • Accommodation is the process of making things clear by changing the shape of the lens.

    Importance of Anatomy

    • Anatomy is important for understanding the structure and function of the visual system.
    • The structure of the eye is designed for optimal performance, and understanding this structure is essential for understanding how the eye works.

    Understanding Vision through Structure and Function of the Human Eye

    • Ocular anatomy and physiology are important for understanding how the eye works.
    • The principles of optics are important for understanding how the eye focuses light.
    • Embryology of the eye is also important for understanding how the eye develops and functions.

    Cornea and Oxygen

    • The cornea gets oxygen and nutrients from the tear film.
    • The tear film is essential for supplying oxygen and nutrients to the cornea.
    • The cornea has an avascular tissue, which means it does not have a blood supply, and relies on the tear film for oxygen and nutrients.
    • The lipid layer of the tear film prevents evaporation and keeps the tear film in place.

    Blood Supply to the Retina

    • The retina has a blood supply that is essential for its function.
    • The blood vessels in the retina are responsible for supplying oxygen and nutrients to the photoreceptors.

    Technology behind Clinical Assessment

    • Technology is important for clinical assessment of the visual system.
    • Research has informed the development of clinical assessment tools and techniques.

    The Power of Research to Inform

    • Research has the power to transform clinical care by providing evidence-based information.
    • Corneal hypoxia and contact lens wear are areas where research has informed clinical practice.
    • The importance of oxygen supply to the cornea is essential for understanding the impact of contact lens wear on the eye.

    Anatomy and Visual Perception

    • Visual perception is the ability to interpret and understand visual information.

    • Visual perception is not just about visual acuity, but also includes form perception, peripheral vision, light perception, and color vision.

    • Microperimetry is a technique used to test the central part of the vision, which can be affected by disease or eye injury.### Visual Perception through Anatomy

    • Higher visual acuity number indicates better vision, allowing patients to see particular spots more clearly.

    • The retina is essential for vision, and no vision is possible without it.

    Understanding Visual Function

    • Homeostasis is essential for normal body functioning, including vision.
    • Understanding anatomy helps appreciate the normal structure of the body, making it easier to identify abnormalities.
    • There should be a correlation between structural and functional findings.

    Key Takeaways

    • Vision encompasses many aspects, not just reading a chart.
    • The absence of a retina means no vision is possible, and no visual function can occur.

    Ocular Anatomy and Physiology

    • The ability of evidence-based research to transform clinical care is crucial.
    • O2 can be transmitted to the eye, and the higher the DK/t, the more it is transmitted.

    Vision, Visual Acuity, and Visual Perception

    • Vision, visual acuity, and visual perception are different concepts.
    • Visual perception includes form perception, peripheral vision, light perception, and color vision.
    • These aspects of vision are not measured by the standard chart.

    Anatomy of the Visual System

    • The eye has a complex anatomy, with the brain playing a crucial role in visual processing.
    • The visual cortex is composed of different areas, each responsible for specific aspects of vision.

    Homeostasis and Clear Vision

    • Homeostasis is the tendency towards a relatively stable equilibrium between interdependent elements.
    • It is a self-regulating process that maintains internal stability in response to changing conditions.
    • Homeostasis is important for proper eye function and health, ensuring optimal temperature, flow, and balance.

    Systemic Homeostasis and Clear Vision

    • Homeostasis in the visual pathway is crucial for clear vision.
    • The homeostatic reflex center for the visual system includes components that work together to maintain optimal visual function.
    • Accommodation is the process of making things clear, and it involves the relaxation or tightening of muscles.

    Homeostasis of the Visual System

    • The homeostasis of the visual system is a complex process that involves the regulation of various factors, including oxygen supply and tear film maintenance.
    • The tear film, composed of a lipid layer, prevents evaporation and keeps the eye moist.
    • Homeostasis is essential for the survival of avascular tissues within the visual system.

    Systemic Medications and Ocular Effects

    • Systemic medications can reach the eye, but it's not easy; local injection is often required to target the eye.
    • The eye has barriers to prevent systemic medications from reaching the retina, choroid, and tear film.

    Amiodarone and the Cornea

    • Amiodarone is an antiarrhythmic medication used to treat irregular heartbeats, introduced in 1961.
    • It works by increasing the time before a heart cell can contract again.
    • Side effects include feeling tired, tremor, nausea, and constipation.
    • Vortex keratopathy (cornea verticillata) is a clinical manifestation of amiodarone on the cornea.
    • Symptoms of vortex keratopathy include blurred vision, and it can impact daily activities.
    • Treatment involves discontinuing amiodarone, and prognosis is generally good.

    Vortex Keratopathy Anatomy

    • Vortex keratopathy occurs when amiodarone accumulates in the lysosomes of the cornea.
    • The condition is reversible, but it may take several months to resolve.

    Plaquenil and the Retina

    • Plaquenil (Hydroxychloroquine) is used to prevent or treat malaria, rheumatoid arthritis, and systemic lupus erythematosus.
    • Side effects include gastrointestinal upset, skin rash, headache, dizziness, and ocular toxicity.
    • Ocular toxicity affects the cornea, ciliary body, and retina.
    • Bull's eye maculopathy is a clinical manifestation of plaquenil on the retina.
    • Early stages of bull's eye maculopathy are asymptomatic, while advanced stages involve colour vision changes and paracentral scotomas.
    • The risk of bull's eye maculopathy depends on the dosage and duration of plaquenil use.
    • Retinal investigations for plaquenil toxicity include electroretinography and visual field tests.

    Embryology of the Eye

    • Embryology is the science that deals with the formation, growth, and development of an embryo or fetus.
    • The development of the human eye begins around the 3rd week of embryonic development.

    Development of the Human Eye

    • During the 3rd week, the eye starts to form, and key features of the human visual system develop.
    • The hyaloid artery provides nutrients to the developing eye and regresses before birth.

    Clinical Presentations of Imperfect Developments

    • Optic Disc Pit: a small, round excavated defect in the optic disc, where there is no vision and no photoreceptors.
    • Persistent Hyaloid Artery: a benign finding that occurs when the hyaloid artery fails to regress.
    • Mittendorf’s Spot: a benign finding that occurs when the hyaloid artery fails to regress.

    Optic Disc Pit

    • Can occur in either eye (RE or LE).
    • Characterized by no vision and no photoreceptors in the affected area.

    Persistent Hyaloid Artery and Mittendorf’s Dot

    • The persistent hyaloid artery is a benign finding that occurs when the artery fails to regress.
    • Mittendorf’s Dot is a small remnant of the hyaloid artery that persists after birth.
    • The tunica vasculosa lentis and vasa hyaloidea propria are two structures that are related to the development of the eye.

    Bergmeister Papilla

    • A small remnant of the hyaloid artery that persists after birth.
    • Characterized by a small elevation on the optic disc.

    Hering's Law of Equal Innervation

    • Yoke muscles receive equal and simultaneous innervation
    • No overshoot

    Agonistic and Antagonistic Muscles

    • Agonist: primary muscle that moves an eye in a given direction
    • Synergist: muscle that assists the agonist in the same direction
    • Antagonist: muscle that moves the eye in the opposite direction of the agonist

    Eye Movements

    • Ductions: monocular eye movements (e.g., elevation, depression)
    • Versions: movements of both eyes in the same direction (e.g., dextroversion, levoversion)
    • Supraversion: elevation of both eyes
    • Infraversion: depression of both eyes

    Extraocular Muscles (EOMs)

    • 7 EOMs: 4 recti (LR, MR, SR, IR), 2 obliques (SO, IO), and levator palpebrae superioris
    • EOM actions: adduction, abduction, elevation, depression, incyclotorsion, excyclotorsion

    Ocular Vasculature

    • Ophthalmic artery supplies the outer portion of the retina
    • Central retinal artery supplies the inner portion of the retina
    • Vortex vein: venous return from the eye
    • Choroid drainage: via vortex vein

    Sympathetic and Parasympathetic Nervous Systems

    • Sympathetic nervous system: causes mydriasis (pupil dilation)
    • Parasympathetic nervous system: causes miosis (pupil constriction)

    Recap

    • EOMs: 7 muscles, 4 recti, 2 obliques, 1 non-movement
    • EOM actions: adduction, abduction, elevation, depression, incyclotorsion, excyclotorsion
    • Ocular vasculature: ophthalmic artery, central retinal artery, vortex vein, choroid drainage

    Cornea

    • The cornea is highly innervated and has a high density of nerve tissue, making it sensitive to pain.
    • The corneal epithelium is made up of 3 cells, and is replaced naturally every 6-7 days through limbal stem cells.
    • The palisades of Vogt are a feature of the limbal conjunctiva.
    • The cornea has a curvature that is steeper along the vertical axis, and its surface can be classified into 4 categories.

    Corneal Refractive Surgery

    • There are 4 types of corneal refractive surgery: Photorefractive Keratectomy (PRK), Laser-Assisted In Situ Keratomileusis (LASIK), Small Incision Lenticule Extraction (SMILE), and Laser Subepithelial Keratomileusis (LASEK).
    • PRK involves removing the epithelium by mechanical means, and then reshaping the stroma using a laser.
    • LASIK involves creating a flap in the cornea, and then reshaping the stroma using a laser.
    • SMILE is the latest technology and does not require the creation of a flap.
    • Antibiotic and steroid eye drops are prescribed before and after surgery, and eye protection is necessary to prevent dry eye.

    Corneal Wound Healing

    • Corneal wound healing after PRK surgery involves the migration of limbal stem cells to the injury site, where they undergo mitosis to form a new epithelial layer.
    • The healing process depends on the interaction between epithelial cells, keratocytes, and the stroma.
    • The epithelial layer is restored through a process of cell migration, proliferation, and differentiation.

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    Related Documents

    OPTM4102 Seminar 1: Fundamentals of Ocular Anatomy and Physiology PDF
    OPTM4102 Seminar 2: Systemic Medications and Ocular Effects PDF
    OPTM4102 Seminar 3: Embryology of the Eye PDF
    4 Extraocular Muscles-Innervation-Vasculature PDF
    6 Cornea and Uvea Seminar 7 PDF

    Description

    This quiz covers the structure and function of the visual system, including the eye and brain, as well as the concept of homeostasis and its importance for clear vision.

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