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Questions and Answers
What is the outer layer of the cornea composed of?
What is the outer layer of the cornea composed of?
The retina is considered to be an outpouching of brain tissue.
The retina is considered to be an outpouching of brain tissue.
True
What is produced by the ciliary body in the eye?
What is produced by the ciliary body in the eye?
Aqueous humour
Glaucoma is characterized by an increase in intraocular fluid ______.
Glaucoma is characterized by an increase in intraocular fluid ______.
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Match the ocular structures with their functions:
Match the ocular structures with their functions:
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What are the components of the uvea?
What are the components of the uvea?
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Descending membrane is a part of the iris structure.
Descending membrane is a part of the iris structure.
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What is the potential cause of secondary glaucoma in veterinary species?
What is the potential cause of secondary glaucoma in veterinary species?
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Which type of neoplasm is most commonly seen in the pinna of dogs?
Which type of neoplasm is most commonly seen in the pinna of dogs?
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Squamous cell carcinoma is most frequently reported in the pinna of grey cats.
Squamous cell carcinoma is most frequently reported in the pinna of grey cats.
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What type of polyp is commonly found in cats and originates in the middle ear or Eustachian tube?
What type of polyp is commonly found in cats and originates in the middle ear or Eustachian tube?
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Ceruminous adenomas are primarily regarded as ______ in dogs.
Ceruminous adenomas are primarily regarded as ______ in dogs.
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Match the following types of neoplasms with their characteristics:
Match the following types of neoplasms with their characteristics:
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Which type of glaucoma has no visible abnormalities in the trabecular meshwork?
Which type of glaucoma has no visible abnormalities in the trabecular meshwork?
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Entropion is a condition where the eyelid margin is everted.
Entropion is a condition where the eyelid margin is everted.
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What is the most common eyelid neoplasm in dogs?
What is the most common eyelid neoplasm in dogs?
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_________ refers to the enlargement of the eye due to increased intraocular pressure.
_________ refers to the enlargement of the eye due to increased intraocular pressure.
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Match the following diseases with their characteristics:
Match the following diseases with their characteristics:
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What condition results from misdirected hairs of the eyelids?
What condition results from misdirected hairs of the eyelids?
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Melanoma in eyelids of dogs is usually malignant.
Melanoma in eyelids of dogs is usually malignant.
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What is the common cause of corneal ulceration?
What is the common cause of corneal ulceration?
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The term '_________' should not be used synonymously with conjunctivitis.
The term '_________' should not be used synonymously with conjunctivitis.
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Match the following causes of glaucoma with their descriptions:
Match the following causes of glaucoma with their descriptions:
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Which condition is characterized by eversion of the eyelid margin?
Which condition is characterized by eversion of the eyelid margin?
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Adenomas are malignant tumors found in the Meibomian glands of dogs.
Adenomas are malignant tumors found in the Meibomian glands of dogs.
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What is the most common cause of conjunctivitis in cats?
What is the most common cause of conjunctivitis in cats?
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______, a condition characterized by the proliferation of the gland of the nictitating membrane, is commonly referred to as 'cherry eye'.
______, a condition characterized by the proliferation of the gland of the nictitating membrane, is commonly referred to as 'cherry eye'.
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Which type of eyelid entropion is caused by spasm of the orbicularis oculi muscle?
Which type of eyelid entropion is caused by spasm of the orbicularis oculi muscle?
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What is the primary cause of otitis externa in dogs?
What is the primary cause of otitis externa in dogs?
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Ciliary body tumors are more common in cats than in dogs.
Ciliary body tumors are more common in cats than in dogs.
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What is the term for the accumulation of neutrophils and fibrin in the anterior chamber?
What is the term for the accumulation of neutrophils and fibrin in the anterior chamber?
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The __________ membrane is a layer of granulation tissue on the anterior surface of the iris.
The __________ membrane is a layer of granulation tissue on the anterior surface of the iris.
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Match the ear disorders with their characteristics:
Match the ear disorders with their characteristics:
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What anatomical structure connects the tympanic cavity with the nasopharynx?
What anatomical structure connects the tympanic cavity with the nasopharynx?
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Feline primary ocular sarcoma is common and occurs in both dogs and cats.
Feline primary ocular sarcoma is common and occurs in both dogs and cats.
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What is the main function of hair cells in the inner ear?
What is the main function of hair cells in the inner ear?
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Accumulation of blood in the anterior chamber is called __________.
Accumulation of blood in the anterior chamber is called __________.
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What type of neoplasms arise from the ciliary body?
What type of neoplasms arise from the ciliary body?
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Chemosis refers to conjunctival swelling.
Chemosis refers to conjunctival swelling.
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What are the consequences of chronic otitis media?
What are the consequences of chronic otitis media?
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The __________ apparatus in the inner ear contributes to balance.
The __________ apparatus in the inner ear contributes to balance.
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Match the types of ear mites with their hosts:
Match the types of ear mites with their hosts:
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What is a descemetocele?
What is a descemetocele?
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Corneal pigmentation is only associated with corneal vascularization.
Corneal pigmentation is only associated with corneal vascularization.
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What is the primary cause of eosinophilic keratitis?
What is the primary cause of eosinophilic keratitis?
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Corneal oedema can be focal, usually caused by a __________, or diffuse, generally due to endothelial damage.
Corneal oedema can be focal, usually caused by a __________, or diffuse, generally due to endothelial damage.
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Match the ocular diseases with their corresponding characteristics:
Match the ocular diseases with their corresponding characteristics:
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Which breed is predisposed to chronic superficial keratitis (pannus)?
Which breed is predisposed to chronic superficial keratitis (pannus)?
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Chronic superficial keratitis primarily affects the anterior uvea.
Chronic superficial keratitis primarily affects the anterior uvea.
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What complication may arise from uveitis?
What complication may arise from uveitis?
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Uveal melanoma is most commonly found in the __________.
Uveal melanoma is most commonly found in the __________.
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Match the condition with its associated risk or cause:
Match the condition with its associated risk or cause:
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What does corneal oedema indicate?
What does corneal oedema indicate?
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Lymphoma may cause diffuse thickening of the iris.
Lymphoma may cause diffuse thickening of the iris.
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What is the main consequence of lens rupture?
What is the main consequence of lens rupture?
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Equine recurrent uveitis is thought to be an __________ disease.
Equine recurrent uveitis is thought to be an __________ disease.
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What can lead to the development of cataracts?
What can lead to the development of cataracts?
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Study Notes
Anatomy and Histology of the Eye
- The eye comprises various structures; understanding normal anatomy is essential for diagnosing diseases.
- Macroscopic evaluation includes the globe, eyelids, Meibomian glands, conjunctiva, third eyelid, lacrimal glands, and extraocular muscles.
- The cornea consists of an outer stratified squamous epithelium, avascular stroma, and endothelial layer with Descemet's membrane.
- The uvea includes the iris, ciliary body, and choroid, contributing to vascular support.
- The lens is biconvex, avascular, and anchored by zonular fibers.
- The retina, an outpouching of brain tissue, features three layers of neurons and is crucial for vision.
- Aqueous humor production occurs in the ciliary body, flowing through the pupil to the trabecular meshwork, contributing to intraocular pressure regulation.
- The blood-eye barrier protects internal structures from immune system exposure.
Postmortem Examination of the Eye
- Rapid postmortem changes necessitate immediate fixation in formalin, Bouin’s, or Davidson’s solution for quality histologic sections.
- Ocular tissues, especially the retina, are highly sensitive to anoxia; mishandling can impair diagnostic efforts.
Diseases of the Globe
- Glaucoma: Characterized by increased intraocular pressure, leading to vision loss and blindness; classified as primary or secondary.
- Primary Glaucoma:
- Goniodysgenesis: Maldevelopment of the filtration angle, prevalent in purebred dogs.
- Primary open-angle glaucoma: No visible trabecular meshwork abnormalities, common in laboratory Beagles.
- Secondary Glaucoma: Caused by obstructions like lens luxation, synechiae, or neoplasia.
- Pathologic changes from increased intraocular pressure primarily affect the optic nerve and retina, leading to retinal and optic nerve atrophy, ganglion cell death, buphthalmia, and corneal changes.
Diseases of the Eyelids and Ocular Adnexa
- Entropion: Eyelid inversion that may cause secondary trichiasis; classified into primary, spastic, and cicatricial types.
- Ectropion: Eyelid eversion, presenting with conjunctival visualization, hyperemia, and keratitis.
- Distichiasis and Trichiasis: Eyelash abnormalities that may necessitate treatment if causing corneal irritation.
- Neoplastic eyelid diseases include:
- Meibomian adenomas: Common benign tumors in dogs.
- Melanomas: Typically benign in dogs, but more aggressive in cats.
- Squamous cell carcinoma: Most common in cats, locally invasive, with metastatic potential.
Diseases of the Conjunctiva
- Conjunctival hyperemia: A response to various local and systemic conditions, not synonymous with conjunctivitis.
- Conjunctivitis: Rare in dogs, often linked to allergies or irritation; common in cats and associated with infectious agents like Herpesvirus and Chlamydia.
Nictitating Membrane and Corneal Diseases
- Prolapse of the gland of the nictitating membrane (“cherry eye”): Associated with weak connective tissue in certain breeds.
- Corneal diseases include keratitis, erosion, ulceration, and associated complications such as vascularization and pigmentation.
- Melting corneal ulcers lead to progressive corneal tissue loss and may create descemetoceles.
Diseases of the Sclera and Uveal Tract
- Nodular granulomatous episcleritis: Common proliferative lesion mistaken for neoplasia.
- Uveitis: Inflammation of the uvea, classified into anterior (iritis) and posterior (choroiditis) types; can cause complications like synechiae and glaucoma.
- Equine recurrent uveitis: Major blindness cause in horses, proposed to be immune-mediated.
Lens and Neoplastic Diseases
- Cataracts: Most significant lens disorder, can occur secondary to various conditions; characterized by denatured lens protein deposits.
- Uveal melanoma: Most common intraocular neoplasm, benign in dogs, potentially malignant in cats.
- Lymphoma and ciliary body tumors can affect intraocular structures.
Other Eye Terminology
- Aqueous flare: Increased protein in aqueous humor; Chemosis: conjunctival swelling; Hypopyon: neutrophil accumulation in the anterior chamber; Hyphema: anterior chamber hemorrhage; Iris bombe: anterior iris bowing; Phthisis bulbi: end-stage globe.
Anatomy and Physiology of the Ear
- The ear consists of three parts: external, middle, and inner ear, each with specific roles in hearing and balance.
- The external ear includes the auricle and auditory canal lined with sebaceous and ceruminous glands.
Diseases of the Ear
- Otitis externa: Common in dogs and cats, involving moisture and microbial infection; results in complex pathogenesis including chronic changes.
- Otitis media: Bacterial inflammation of the tympanic cavity; can lead to severe complications if untreated.
Diseases of the Middle Ear
- Bacterial organisms, such as Mycoplasma bovis and Pasteurella multocida, often cause otitis media in cattle with potential for systemic involvement.### Otitis Media in Animals
- Calves: Escherichia coli can cause sporadic otitis media cases.
- Dogs and Cats: Often linked to chronic otitis externa; in Cavalier King Charles spaniels, primary secretory otitis media is common.
- Inflammatory Polyps: These may develop in the middle ear, particularly with otitis media in dogs.
- Cats with Cryptococcosis: Otitis media associated with vestibular disease may be a primary clinical complaint.
Otitis Media in Specific Animals
- Pigs: Unilateral otitis media can occur, associated with pathogens like haemolytic Streptococcus, Actinobacillus pleuropneumoniae, and Mycoplasma hyorhinis.
- Horses: Often not related to otitis externa; can lead to temporohyoid osteoarthropathy and has instances of mycotic otitis media.
Diseases of the Inner Ear
- Otitis Interna: Frequently arises from middle ear inflammation; leads to vestibular dysfunction; may progress to suppurative meningitis and encephalitis.
- Vestibular Dysfunction Signs: Includes head tilt, falling toward the affected side, ataxia, and nystagmus.
- Causes: Can be due to otitis media, trauma, drugs, and neoplasia. Idiopathic vestibular disease noted in older dogs and cats, characterized by sudden onset and rapid remission without identifiable lesions.
Neoplasia of the Ear
- General: Ear neoplasms resemble skin tumors; primary tumours of ceruminous glands and auditory epithelium are rare.
- Cutaneous Histiocytoma: Commonly found in the pinna of dogs.
- Squamous Cell Carcinoma: Frequently seen in the pinna of white cats and sheep exposed to UV light.
- Ceruminous Adenoma/Adenocarcinoma: Common in dogs (mostly benign) and in both benign and malignant forms in cats; adenomas characterized by well-differentiated tubular cystic mass.
- Nasopharyngeal Polyps: Predominantly in cats; consist of loose connective tissue with small blood vessels, covered by ciliated columnar epithelium; origin is unknown, typically from the middle ear or Eustachian tube.
- Inflammatory Polyps: Observed in dogs with chronic otitis externa; histologically reveal hyperplastic surface epithelium and leukocytic inflammation.
Studying That Suits You
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Description
Test your knowledge about the various structures and functions of the eye in this quiz. Explore topics such as the cornea, retina, and uvea, and understand how they contribute to vision. This quiz will help solidify your understanding of ocular anatomy and their respective functions.