Anatomy and Disorders of the Cornea
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Questions and Answers

What is the main function of the cornea?

  • Vision
  • Protecting the eye
  • Light absorption
  • Refracting light (correct)

    • The cornea is completely opaque.

    False

    What is the thickness range of the cornea in most species?

    0.5-2mm

    The __________ is the anterior limiting membrane of the cornea.

    <p>Bowman's layer</p> Signup and view all the answers

    Which of the following is NOT a congenital disorder of the cornea?

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

    Match the following corneal conditions with their descriptions:

    <p>Microcornea = Abnormally small cornea Macrocornea = Abnormally large cornea Dermoids = Ectopic piece of skin on the cornea Coloboma = Absence of a full segment of the cornea</p> Signup and view all the answers

    The corneal epithelium is replaced every 4-8 days.

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

    Keratitis is the inflammation of the __________.

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

    What characteristic distinguishes ciliary blood vessels from conjunctival blood vessels?

    <p>They are darker in color</p> Signup and view all the answers

    Corneal ulceration can only be superficial.

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

    What does hypopyon refer to?

    <p>Accumulation of inflammatory exudate in the anterior chamber of the eyeball</p> Signup and view all the answers

    The process by which the normally avascular cornea gets invaded by blood vessels as a defensive mechanism is called __________.

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

    Match the types of superficial keratitis with their descriptions:

    <p>Superficial punctate keratitis = Epithelial and subepithelial lesions Superficial abscesses = Abscess formation at superficial layers Pannus = Chronic diffuse inflammatory condition Keratitis = General inflammation of the cornea</p> Signup and view all the answers

    What is the common treatment for superficial keratitis?

    <p>Topical corticosteroids and antibiotics</p> Signup and view all the answers

    Pigmentation of the cornea is a specific response to inflammation.

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

    What is the initial symptom of superficial keratitis?

    <p>Grayish haze at the temporal limbus</p> Signup and view all the answers

    Identify the breed predisposed to degenerative pannus.

    <p>German shepherd</p> Signup and view all the answers

    Superficial keratitis can result in blindness if left untreated.

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

    What treatment is indicated for moderately advanced cases of superficial keratitis?

    <p>Subconjunctival corticosteroids</p> Signup and view all the answers

    The condition known as keratoconjunctivitis sicca is secondary to __________ insufficiency.

    <p>lacrimal gland</p> Signup and view all the answers

    Match the treatments with their corresponding conditions:

    <p>Beta radiation = Advanced superficial keratitis Chemical cauterization = Granulation tissue Periotomy = Exuberant granulation tissue Topical corticosteroids = Early superficial keratitis</p> Signup and view all the answers

    Which of the following is a potential cause of pigmentary keratitis?

    <p>Keratoconjunctivitis sicca</p> Signup and view all the answers

    Pigmentary keratitis only occurs in the superficial layers of the cornea.

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

    What is a symptom of pigmented keratitis?

    <p>Presence of pigments and possible corneal opacities</p> Signup and view all the answers

    Which of the following is NOT a symptom of interstitial keratitis?

    <p>Corneal ulcer formation</p> Signup and view all the answers

    Removal of pigments in pigmentary keratitis is indicated if vision is impaired.

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

    What are two mechanical causes of ulcerative keratitis?

    <p>Abrasions and foreign body injury</p> Signup and view all the answers

    ____ is a systemic disease that can cause interstitial keratitis in dogs.

    <p>Canine distemper</p> Signup and view all the answers

    Which treatment method is commonly used for interstitial keratitis?

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

    Match the cause with its associated type of keratitis:

    <p>Abrasions = Ulcerative keratitis Canine distemper = Interstitial keratitis Vitamin A deficiency = Ulcerative keratitis Infection from superficial cornea = Interstitial keratitis</p> Signup and view all the answers

    Which of the following is true regarding the treatment of pigmentary keratitis?

    <p>Pigment removal is only considered for visual impairment.</p> Signup and view all the answers

    Corticosteroids are recommended as a treatment for ulcerative keratitis.

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

    What is the initial treatment step for iris prolapse?

    <p>Flush the wound with boric acid solution</p> Signup and view all the answers

    Iris staphyloma involves the protrusion of the iris through a ruptured corneal ulcer.

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

    What is the treatment for hypopyon?

    <p>Paracentesis and aspiration of the inflammatory exudate</p> Signup and view all the answers

    The _____ membrane flap is a treatment option for iris staphyloma.

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

    Match the following conditions with their treatments:

    <p>Iris prolapse = Re-deposit iris or amputation Hypopyon = Paracentesis and aspiration Anterior synechia = Atropine 1% application Panophthalmitis = Enucleation or exenteration</p> Signup and view all the answers

    Which treatment is used for anterior synechia?

    <p>Application of atropine 1%</p> Signup and view all the answers

    In hypopyon, topical antibiotics are ineffective.

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

    What is the purpose of injecting sterile saline solution into the anterior chamber during iris staphyloma treatment?

    <p>To restore the anterior chamber</p> Signup and view all the answers

    Study Notes

    Anatomy of the Cornea

    • The cornea is the transparent outer layer of the eye, responsible for focusing light
    • It is horizontally elliptical or pear-shaped in horses and cattle, and nearly circular in dogs and cats
    • The thickness of the cornea varies between 0.5-2mm and differs from the center to the periphery
    • Canine and bovine corneas are thickest at the center, while equine corneas are thickest at the limbus
    • The cornea consists of five layers: epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium
    • Epithelium is constantly desquamated and replaced every 4-8 days
    • The stroma forms 90% of the thickness of the cornea
    • Descemet's membrane is the basement membrane of the endothelium

    Congenital Disorders of the Cornea

    • Microcornea is an abnormally small cornea
    • Macrocornea is a large cornea within an otherwise normal globe
    • Dermoids are ectopic pieces of skin present on the cornea or conjunctiva
    • Coloboma of the cornea is the absence of a full segment of the cornea, a rare condition

    Acquired Disorders of the Cornea

    • Keratitis is inflammation of the cornea.
      • Symptoms: pain (photophobia, blepharospasm), discharge, conjunctiva and ciliary blood vessel injection, loss of corneal transparency, corneal vascularization, ulceration, pigmentation, hypopyon
    • Types of Keratitis:
      • Superficial Keratitis:
        • Superficial Punctate Keratitis: fine circular to large white opacities
        • Superficial Abscesses: green-yellowish swellings, often due to trauma or foreign body
        • Pannus: chronic diffuse inflammatory condition, characterized by subepithelial connective tissue infiltration and vascularization
        • Keratoconjunctivitis Sicca: secondary to lacrimal gland insufficiency
        • Exuberant granulation tissue: builds up on the cornea surface after injury
        • Pigmentary Keratitis: pigment deposition in the cornea, often due to irritants like trichiasis, distichiasis, entropion, or prior keratitis
      • Interstitial or Deep Keratitis: inflammation of the stroma, Descemet's membrane, and endothelium
        • Causes: extension of infection from superficial layers, systemic diseases (canine distemper, infectious hepatitis, leptospirosis), traumatic injuries
        • Symptoms: corneal opacity, deep vascularization, conjunctival and ciliary injection, hypopyon
      • Ulcerative Keratitis: inflammation of the cornea with ulcer formation
        • Causes: mechanical (abrasions, foreign bodies, entropion), infectious (bacterial, viral, fungal, chlamydial), metabolic, neurotrophic
        • Treatment:
        • Iris Prolapse: protrusion of the iris through a corneal ulcer
        • Iris Staphyloma: protrusion of the iris covered with fibrin and epithelium
        • Hypopyon: accumulation of inflammatory exudate in the anterior chamber
        • Anterior Synechia: adhesions between the iris and corneal endothelium
        • Panophthalmitis: severe purulent inflammation of the eyeball

    Treatments for Corneal Disorders

    • Superficial Keratitis: topical corticosteroids, antibiotics, yellow mercuric oxide
    • Superficial Abscesses: opening and suction, curettage, superficial keratectomy
    • Pannus: topical corticosteroids, subconjunctival corticosteroids, beta radiation, chemical cauterization, superficial keratectomy, periotomy
    • Exuberant Granulation Tissue: periotomy, surgical removal
    • Pigmentary Keratitis: elimination of the cause, superficial keratectomy if vision is impaired
    • Interstitial Keratitis: topical atropine sulfate, corticosteroids, antibiotics
    • Ulcerative Keratitis: topical antibiotics, atropine, surgical repair of wounds
    • Iris Prolapse: re-positioning or amputation of the iris, suturing corneal wound, third eyelid flap
    • Iris Staphyloma: excision of the protruded iris, suture of corneal wound, nictitating membrane flap
    • Hypopyon: paracentesis, aspiration, alfapsin enzyme injection
    • Anterior Synechia: atropine, surgery to remove adhesions
    • Panophthalmitis: enucleation, exenteration, evisceration

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    Cornea Disorders (Lec 3 Pt 1) PDF

    Description

    Explore the intricate anatomy of the cornea, its structure, and its various congenital disorders. Learn about the layers of the cornea, its variations across different species, and specific congenital conditions like microcornea and coloboma. This quiz will enhance your understanding of both normal and abnormal corneal conditions.

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