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ACVO Veterinary Ophthalmology study materials
ACVO Veterinary Ophthalmology study resources

ACVO Veterinary Ophthalmology practice questions

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Question 1General Veterinary Ophthalmology

Which structure is primarily responsible for producing the aqueous humor in the canine eye?

  1. Trabecular meshwork
  2. Lens capsule
  3. Ciliary body epithelium Correct answer.
  4. Corneal endothelium

Explanation

Aqueous humor is actively secreted by the ciliary epithelium (primarily the nonpigmented epithelium of the ciliary processes). The corneal endothelium and trabecular meshwork regulate fluid dynamics but do not produce aqueous. The lens capsule is a passive basement membrane structure.

Question 2General Veterinary Ophthalmology

In the normal mammalian eye, aqueous humor exits primarily through which route?

  1. Vitreous base
  2. Optic nerve sheath
  3. Retinal pigment epithelium
  4. Iridocorneal angle into the uveoscleral pathway Correct answer.

Explanation

The majority of aqueous outflow occurs via the conventional (trabecular) pathway at the iridocorneal angle, with a smaller fraction leaving through the uveoscleral pathway. The optic nerve sheath, RPE, and vitreous base are not significant outflow routes.

Question 3General Veterinary Ophthalmology

What is the normal consensual pupillary light reflex in a healthy dog?

  1. Neither pupil responds to light directly
  2. Both pupils constrict when one eye is illuminated Correct answer.
  3. Only the stimulated eye constricts
  4. Both pupils dilate when one eye is illuminated

Explanation

Light entering one eye activates the pretectal nucleus bilaterally, so both pupils constrict (direct and consensual response). This bilateral projection underlies the consensual reflex. A unilateral efferent defect abolishes both direct and consensual responses in the affected eye.

Question 4General Veterinary Ophthalmology

Which of the following is the most common primary intraocular tumor in dogs?

  1. Lymphoma
  2. Ciliary body adenoma
  3. Choroidal melanoma
  4. Iris melanoma Correct answer.

Explanation

Iris melanoma (feline diffuse iris melanoma is common in cats; in dogs, anterior uveal melanocytic tumors are the most frequently reported primary intraocular neoplasms). Choroidal melanoma is less common in dogs. Lymphoma more often involves the uvea secondarily as part of multicentric disease.

Question 5General Veterinary Ophthalmology

Which clinical sign is most characteristic of Horner syndrome?

  1. Miosis with exophthalmos and third eyelid protrusion
  2. Miosis with ptosis and enophthalmos Correct answer.
  3. Mydriasis with exophthalmos and lagophthalmos
  4. Mydriasis with ptosis and enophthalmos

Explanation

Horner syndrome results from loss of sympathetic innervation to the eye and produces miosis, ptosis, enophthalmos, and third eyelid protrusion. The pupil is constricted because the sympathetically innervated dilator muscle is denervated. Exophthalmos is not a feature.

Question 6General Veterinary Ophthalmology

A Schirmer tear test I reading of 8 mm/min in a dog is best interpreted as which of the following?

  1. Clearly elevated tear production
  2. Borderline low, warranting repeat testing Correct answer.
  3. Indicative of glaucoma
  4. Normal tear production

Explanation

The reference range for STT I in dogs is roughly 15-25 mm/min; values below about 10 mm/min are considered borderline and should be repeated, especially with clinical signs. Values under 5 mm/min strongly suggest keratoconjunctivitis sicca. STT does not assess intraocular pressure.

Question 7General Veterinary Ophthalmology

Which ocular structure is the primary refractive element of the eye?

  1. Vitreous
  2. Lens
  3. Cornea Correct answer.
  4. Retina

Explanation

The cornea provides approximately two-thirds of the eye's refractive power because of the large difference in refractive index between air and corneal tissue. The lens provides the remainder and allows accommodation. The vitreous and retina are not refractive elements in the same sense.

Question 8General Veterinary Ophthalmology

What is the normal range for intraocular pressure in a dog using applanation tonometry?

  1. 45 to 60 mmHg
  2. 2 to 6 mmHg
  3. 30 to 40 mmHg
  4. 10 to 25 mmHg Correct answer.

Explanation

Normal canine intraocular pressure is generally reported between about 10 and 25 mmHg, though values vary with instrument and technique. Pressures below 10 mmHg suggest hypotony, and values consistently above 25 mmHg suggest ocular hypertension or glaucoma. The other ranges fall outside normal physiology.

Question 9General Veterinary Ophthalmology

Which of the following best describes the normal menace response in a dog?

  1. A blink elicited by a bright light
  2. A blink elicited by touching the cornea
  3. A blink elicited by a loud sound
  4. A blink elicited by a threatening gesture without touching the eye Correct answer.

Explanation

The menace response is a learned cortical response in which a visual threat produces a blink without physical contact. It requires intact vision, facial nerve function, and cerebral cortex. Touch and light elicit different reflexes (palpebral and dazzle, respectively).

Question 10General Veterinary Ophthalmology

A cat presents with a sudden onset of mydriasis, absent pupillary light reflex, and normal menace in one eye. Which lesion localization is most likely?

  1. Oculomotor nerve lesion Correct answer.
  2. Trigeminal nerve lesion
  3. Optic nerve lesion
  4. Facial nerve lesion

Explanation

Mydriasis with absent pupillary light reflex but preserved vision (normal menace) indicates an efferent (parasympathetic) defect, typically an oculomotor nerve lesion affecting the iris sphincter. An optic nerve lesion would abolish vision and the menace response. Facial and trigeminal lesions affect eyelid or sensation, not the pupil.

Question 11General Veterinary Ophthalmology

Which of the following is the most appropriate initial diagnostic test for a dog suspected of keratoconjunctivitis sicca?

  1. Electroretinography
  2. Schirmer tear test Correct answer.
  3. Gonioscopy
  4. Fluorescein staining

Explanation

Keratoconjunctivitis sicca is a quantitative or qualitative tear deficiency, so the Schirmer tear test is the primary diagnostic test. Fluorescein staining identifies corneal ulceration, gonioscopy evaluates the iridocorneal angle, and ERG assesses retinal function. None of these measures tear production.

Question 12General Veterinary Ophthalmology

A dog has a fluorescein-stained corneal defect. Which of the following best describes the purpose of the Seidel test?

  1. To detect tear film breakup time
  2. To measure corneal thickness
  3. To detect aqueous leakage from a full-thickness corneal wound Correct answer.
  4. To assess corneal sensation

Explanation

The Seidel test uses concentrated fluorescein to detect a stream of aqueous leaking from a full-thickness corneal wound, appearing as a clear line through the green stain. It does not measure thickness, tear film stability, or corneal sensation. Those are assessed by pachymetry, tear breakup time, and the corneal reflex, respectively.

Question 13General Veterinary Ophthalmology

Which of the following is the primary goal of medical therapy in canine primary glaucoma?

  1. Increase aqueous humor production and increase outflow
  2. Reduce aqueous humor production and reduce outflow
  3. Increase aqueous humor production and reduce outflow
  4. Reduce aqueous humor production and increase outflow Correct answer.

Explanation

Glaucoma therapy aims to lower intraocular pressure by reducing aqueous production (carbonic anhydrase inhibitors, beta blockers, prostaglandin analogs) and enhancing outflow (prostaglandin analogs, miotics). Increasing production or reducing outflow would worsen the pressure elevation. The goal is to preserve vision and comfort.

Question 14General Veterinary Ophthalmology

A young dog has a persistent pupillary membrane that crosses the pupil. Which embryologic structure fails to regress?

  1. Anterior chamber angle
  2. Optic vesicle
  3. Hyaloid artery
  4. Tunica vasculosa lentis Correct answer.

Explanation

Persistent pupillary membranes arise from failure of regression of the tunica vasculosa lentis, the vascular network on the anterior lens capsule. The hyaloid artery gives rise to persistent hyaloid remnants. The anterior chamber angle and optic vesicle are unrelated to this structure.

Question 15General Veterinary Ophthalmology

Which of the following is the most common cause of conjunctivitis in cats?

  1. Feline calicivirus
  2. Chlamydia felis
  3. Mycoplasma felis
  4. Feline herpesvirus-1 Correct answer.

Explanation

Feline herpesvirus-1 is the most frequently identified infectious cause of feline conjunctivitis, often with recurrent or chronic disease. Calicivirus, Chlamydia, and Mycoplasma can also cause conjunctivitis but are less commonly the primary cause. Diagnosis often involves PCR and clinical signs.

Question 16General Veterinary Ophthalmology

Which of the following best describes the appearance of an indolent corneal ulcer in a dog?

  1. A diffuse corneal edema with neovascularization
  2. A deep stromal defect with melting and hypopyon
  3. A perforating wound with iris prolapse
  4. A superficial epithelial defect with loose epithelial margins and no stromal loss Correct answer.

Explanation

Indolent (boxer) ulcers are superficial epithelial defects with raised or loose epithelial edges and deficient epithelial adhesion, without significant stromal loss. Melting ulcers involve stromal collagenolysis, and perforating wounds involve full-thickness loss. Diffuse edema and neovascularization suggest other processes.

Question 17General Veterinary Ophthalmology

A dog presents with a cherry eye. Which structure is prolapsed?

  1. Lacrimal gland
  2. Third eyelid gland Correct answer.
  3. Meibomian gland
  4. Nictitating membrane cartilage

Explanation

Cherry eye refers to prolapse of the gland of the third eyelid (nictitans gland) from its normal position. The cartilage and lacrimal and meibomian glands are separate structures. The prolapsed gland appears as a pink-red mass at the medial canthus.

Question 18General Veterinary Ophthalmology

Which of the following is the most common cause of uveitis in dogs?

  1. Bacterial infection
  2. Trauma
  3. Immune-mediated disease Correct answer.
  4. Neoplasia

Explanation

Immune-mediated uveitis is the most commonly diagnosed category in dogs, though many cases are idiopathic and systemic causes should be excluded. Infectious, traumatic, and neoplastic causes are important but less common overall. A thorough systemic workup is still warranted.

Question 19General Veterinary Ophthalmology

Which of the following findings is most consistent with retinal detachment on fundic examination?

  1. Diffuse tapetal hyperreflectivity with vascular attenuation
  2. A normal optic disc with peripapillary edema
  3. A focal area of hyperreflectivity with pigment clumping
  4. A veil-like elevated retina that does not follow the choroidal pattern Correct answer.

Explanation

A detached retina appears as an elevated, veil-like membrane that billows into the vitreous and obscures the underlying choroidal pattern. Hyperreflectivity with pigment clumping suggests retinal degeneration or scarring. Optic disc edema and vascular attenuation are separate findings.

Question 20General Veterinary Ophthalmology

Which of the following is the most appropriate treatment for a dog with a deep corneal ulcer and marked stromal melting?

  1. Topical antibiotic and systemic anti-collagenase therapy with possible surgical stabilization Correct answer.
  2. Topical atropine alone
  3. Topical corticosteroid alone
  4. Observation without treatment

Explanation

Melting ulcers require antimicrobial therapy to control infection and anti-collagenase treatment (such as serum or EDTA) to limit stromal loss, often with surgical stabilization (conjunctival graft). Corticosteroids are contraindicated because they inhibit healing and promote collagenolysis. Observation and atropine alone are inadequate.

Question 21General Veterinary Ophthalmology

Which of the following best describes the purpose of a conjunctival graft in corneal surgery?

  1. To reduce intraocular pressure
  2. To correct entropion
  3. To provide vascular supply and structural support to a compromised cornea Correct answer.
  4. To remove the lens

Explanation

A conjunctival graft brings blood supply and structural support to a deep or melting corneal defect, promoting healing and reducing the risk of perforation. It does not lower intraocular pressure, correct eyelid position, or address the lens. Grafts are commonly used for descemetoceles and deep ulcers.

Question 22General Veterinary Ophthalmology

A dog with a mature cataract is evaluated for phacoemulsification. Which preoperative finding most strongly predicts a good visual outcome?

  1. A normal intraocular pressure
  2. A normal electroretinogram and intact retinal function Correct answer.
  3. A normal Schirmer tear test
  4. A positive menace response with a dilated pupil

Explanation

The ERG assesses retinal function and is the key preoperative test to confirm that vision loss is due to the cataract rather than retinal disease. A menace response can be absent with a mature cataract and is not predictive. Tear production and intraocular pressure are important but do not assess retinal function.

Question 23General Veterinary Ophthalmology

Which of the following is the mechanism of action of prostaglandin analogs such as latanoprost in glaucoma therapy?

  1. Increased pupil dilation
  2. Increased trabecular outflow
  3. Decreased aqueous production
  4. Increased uveoscleral outflow Correct answer.

Explanation

Prostaglandin analogs lower intraocular pressure primarily by increasing uveoscleral outflow through remodeling of the ciliary body extracellular matrix. They do not primarily reduce aqueous production or act on the trabecular meshwork. Mydriasis is not their therapeutic mechanism.

Question 24General Veterinary Ophthalmology

Which of the following best explains why the menace response is absent in a dog with a mature cataract but the dazzle reflex is present?

  1. The dazzle reflex requires an intact lens, while the menace response does not
  2. The menace response requires cortical processing of a visual image, while the dazzle reflex is a subcortical response to light Correct answer.
  3. The menace response is a brainstem reflex, while the dazzle reflex is cortical
  4. The menace response is mediated by the facial nerve, while the dazzle reflex is mediated by the optic nerve

Explanation

The menace response is a learned cortical response requiring perception of a threatening image, so it is lost when the image is obscured by a cataract. The dazzle reflex is a subcortical response to light and can persist. Both responses require an intact optic nerve and facial nerve.

Question 25General Veterinary Ophthalmology

A cat presents with diffuse iris thickening, pigment dispersion, and a history of chronic uveitis. Which of the following is the most important differential diagnosis?

  1. Feline herpesvirus keratitis
  2. Anterior lens luxation
  3. Corneal sequestrum
  4. Feline diffuse iris melanoma Correct answer.

Explanation

Diffuse iris melanoma in cats presents with progressive iris thickening, pigment dispersion, and dyscoria, and can mimic chronic uveitis. Herpesvirus keratitis affects the cornea, corneal sequestrum is a corneal lesion, and lens luxation involves lens displacement. None of these produce diffuse iris thickening with pigment dispersion.

Question 26General Veterinary Ophthalmology

Which structure produces the aqueous humor that fills the anterior chamber of the eye?

  1. Corneal endothelium
  2. Retinal pigment epithelium
  3. Lens capsule
  4. Ciliary body epithelium Correct answer.

Explanation

Aqueous humor is actively secreted by the ciliary body epithelium, primarily the nonpigmented epithelium of the ciliary processes. It then flows through the pupil into the anterior chamber and drains at the iridocorneal angle.

Question 27General Veterinary Ophthalmology

Which of the following best describes the normal consensual pupillary light reflex?

  1. Shining light in one eye causes both pupils to dilate
  2. Shining light in one eye causes both pupils to constrict Correct answer.
  3. Shining light in one eye causes only that pupil to constrict
  4. Shining light in one eye causes the opposite pupil to dilate

Explanation

Light stimulation of one retina travels via the optic nerve and pretectal nucleus to both Edinger-Westphal nuclei, so both pupils constrict. This bilateral response is the consensual component.

Question 28General Veterinary Ophthalmology

Which of the following is the principal function of the eyelids?

  1. Producing aqueous humor
  2. Distributing the tear film and protecting the globe Correct answer.
  3. Focusing light onto the retina
  4. Detecting changes in light intensity

Explanation

Eyelids spread the precorneal tear film with each blink, remove debris, and provide mechanical protection of the globe. They also contribute to tear film lipid from the meibomian glands.

Question 29General Veterinary Ophthalmology

A cat is presented with a cloudy eye and a shallow anterior chamber after a fight wound. Which of the following ocular structures is most at risk of rupture if the globe is palpated firmly?

  1. The optic nerve head
  2. The retina at the ora cava
  3. The lens at the equator
  4. The cornea at the site of a full-thickness laceration Correct answer.

Explanation

A full-thickness corneal wound is the weakest point of the globe; external pressure can extrude intraocular contents through the defect. The eye should be handled gently and globe pressure avoided.

Question 30General Veterinary Ophthalmology

Which of the following species has a fundus that commonly appears uniformly reflective and lacks a distinct tapetal region?

  1. The horse
  2. The cat
  3. The dog
  4. The rabbit Correct answer.

Explanation

Rabbits lack a tapetum lucidum, so their fundus appears uniformly reddish and nonreflective. Dogs, cats, and horses all have a tapetum lucidum and a reflective fundic region.

Question 31General Veterinary Ophthalmology

Which of the following best describes the normal appearance of the optic disc on fundic examination?

  1. A darkly pigmented raised mass at the center of the fundus
  2. A bright reflective band across the dorsal fundus
  3. A network of vessels without a discernible disc
  4. A pale, slightly cupped area where retinal vessels converge Correct answer.

Explanation

The optic disc is the site where retinal ganglion cell axons exit the eye; it appears pale relative to the surrounding fundus and is where retinal vessels emerge. Its margins are typically distinct.

Question 32General Veterinary Ophthalmology

Which of the following structures is responsible for the corneal reflex that occurs when the cornea is touched?

  1. Optic nerve and oculomotor nerve
  2. Sympathetic fibers to the iris dilator
  3. Facial nerve alone
  4. Ophthalmic branch of the trigeminal nerve and facial nerve Correct answer.

Explanation

The corneal (blink) reflex requires afferent input via the ophthalmic branch of the trigeminal nerve and efferent motor output via the facial nerve to the orbicularis oculi. Loss of either limb abolishes the reflex.

Question 33General Veterinary Ophthalmology

Which of the following is the most appropriate first step when a dog presents with an acutely painful, red eye and a hazy cornea?

  1. Perform a complete ophthalmic examination including tonometry and fluorescein staining Correct answer.
  2. Schedule elective cataract surgery for the next week
  3. Apply a topical anesthetic and send the dog home
  4. Instill a corticosteroid-containing ointment before examination

Explanation

A painful red eye may reflect glaucoma, ulceration, or uveitis, each requiring different therapy. Tonometry and fluorescein staining are essential to distinguish these before any treatment is chosen.

Question 34General Veterinary Ophthalmology

A dog has a dilated pupil that does not respond to light in a normally sighted eye. Which of the following is the most likely explanation?

  1. Increased parasympathetic tone to the iris sphincter
  2. Excess aqueous humor production
  3. Disruption of the parasympathetic supply to the iris sphincter Correct answer.
  4. Loss of sympathetic tone to the iris dilator

Explanation

The iris sphincter is innervated by parasympathetic fibers from the oculomotor nerve; loss of this input leaves the pupil dilated and unresponsive to light. Sympathetic loss produces a constricted pupil, not a dilated one.

Question 35General Veterinary Ophthalmology

A horse presents with a cloudy cornea and a positive fluorescein stain. Which of the following features most strongly suggests a melting ulcer requiring aggressive therapy?

  1. Presence of a small superficial punctate stain
  2. Gelatinous, malacic stroma with a rapidly enlarging defect Correct answer.
  3. A dry, brown-stained epithelial defect
  4. A superficial linear epithelial defect only

Explanation

Collagenolysis produces a gelatinous, malacic appearance and rapid enlargement, marking an actively melting ulcer that risks perforation. Such cases require aggressive medical and often surgical intervention.

Question 36General Veterinary Ophthalmology

Which of the following best explains why topical atropine is used in the management of anterior uveitis?

  1. It relieves ciliary spasm and reduces the risk of synechia formation Correct answer.
  2. It directly suppresses the inflammatory cells in the anterior chamber
  3. It accelerates corneal epithelial healing
  4. It reduces aqueous humor production to lower intraocular pressure

Explanation

Atropine paralyzes the iris sphincter and ciliary muscle, relieving painful spasm and keeping the pupil mobile to reduce posterior synechia formation. It does not treat the underlying inflammation itself.

Question 37General Veterinary Ophthalmology

A dog has a dry, lusterless cornea with a mucoid discharge and a Schirmer tear test I of 5 mm/min. Which of the following is the most appropriate chronic therapy?

  1. Topical corticosteroid alone
  2. Topical cyclosporine or tacrolimus to stimulate tear production Correct answer.
  3. Topical antibiotic alone
  4. Topical atropine alone

Explanation

Immune-mediated keratoconjunctivitis sicca is managed by stimulating lacrimal secretion with cyclosporine or tacrolimus. Tear substitutes and control of secondary infection are adjuncts but do not address the underlying deficiency.

Question 38General Veterinary Ophthalmology

A young dog is presented with a cloudy lens and a history of diabetes mellitus. Which of the following best explains the rapid cataract formation?

  1. Intralenticular accumulation of sorbitol from the polyol pathway Correct answer.
  2. Autoimmune destruction of lens epithelial cells
  3. Deposition of cholesterol crystals within the lens
  4. Loss of the lens capsule with leakage of aqueous

Explanation

In diabetes, excess glucose is converted to sorbitol within the lens, drawing in water osmotically and causing lens fiber swelling and opacification. This is the classic mechanism of diabetic cataract.

Question 39General Veterinary Ophthalmology

Which of the following is the most appropriate initial management for a dog with acute congestive glaucoma and an intraocular pressure of 60 mm Hg?

  1. Medical therapy to lower intraocular pressure urgently, followed by surgical assessment Correct answer.
  2. Observation with recheck in one week
  3. Topical corticosteroid alone
  4. Topical atropine alone

Explanation

Acute congestive glaucoma is an emergency; rapid medical reduction of intraocular pressure preserves vision and prepares the eye for definitive surgical management. Delay risks irreversible optic nerve damage.

Question 40General Veterinary Ophthalmology

A dog presents with a red, painful eye, a shallow anterior chamber, and a dark mass protruding from the limbus. Which of the following is the most likely diagnosis?

  1. Anterior uveal prolapse through a limbal wound Correct answer.
  2. Simple conjunctivitis
  3. A corneal dystrophy
  4. A prolapsed nictitating membrane gland

Explanation

A dark, pigmented mass at the limbus with a shallow anterior chamber suggests uveal tissue prolapsing through a full-thickness wound. This is a surgical emergency to preserve the globe.

Question 41General Veterinary Ophthalmology

Which of the following best describes the purpose of a lateral canthotomy in ophthalmic surgery?

  1. To remove the nictitating membrane
  2. To widen the palpebral fissure and improve access to the globe or posterior orbit Correct answer.
  3. To correct entropion of the lower lid
  4. To reduce intraocular pressure by draining aqueous

Explanation

A lateral canthotomy extends the palpebral fissure laterally to improve exposure of the globe and orbit for surgery or to relieve orbital crowding. It is not a pressure-lowering procedure.

Question 42General Veterinary Ophthalmology

A cat with a chronic red eye has a corneal sequestrum. Which of the following best describes this lesion?

  1. A fluid-filled cyst within the iris
  2. A dark, plaque-like area of devitalized corneal stroma Correct answer.
  3. A superficial epithelial erosion
  4. A pigmented mass arising from the limbus

Explanation

A corneal sequestrum is a region of devitalized, pigmented stroma that appears as a dark plaque, most often in cats. It is distinct from a simple epithelial erosion.

Question 43General Veterinary Ophthalmology

A dog has a cherry eye. Which of the following is the most appropriate initial surgical approach in most cases?

  1. Repositioning and anchoring the prolapsed gland rather than excising it Correct answer.
  2. Topical antibiotic therapy alone
  3. Excision of the prolapsed gland
  4. Enucleation of the globe

Explanation

The prolapsed gland of the nictitating membrane should be replaced and anchored to preserve tear production. Excision risks subsequent keratoconjunctivitis sicca.

Question 44General Veterinary Ophthalmology

Which of the following best describes the normal appearance of the tapetum lucidum in a dog?

  1. A reflective region in the dorsal fundus Correct answer.
  2. A pigmented region in the ventral fundus
  3. A pale disc where vessels converge
  4. A vascular network on the iris surface

Explanation

The tapetum lucidum lies in the dorsal fundus and reflects light back through the retina to improve night vision. It appears as a reflective, variably colored region.

Question 45General Veterinary Ophthalmology

A dog is presented with a sudden onset of blindness in one eye and a dilated, unresponsive pupil. Which of the following findings would most help distinguish a retinal detachment from an optic neuritis?

  1. Presence of a normal corneal reflex
  2. Presence of a normal dazzle reflex
  3. Presence of a normal menace response
  4. Fundic examination showing an elevated, folded retina Correct answer.

Explanation

Fundic examination directly visualizes an elevated, detached retina, whereas optic neuritis may show a swollen disc without retinal elevation. The other reflexes do not localize the lesion to retina versus optic nerve.

Question 46General Veterinary Ophthalmology

Which of the following is the most appropriate method to confirm a diagnosis of a corneal ulcer in a dog?

  1. Fluorescein staining of the cornea Correct answer.
  2. Schirmer tear test
  3. Tonometry
  4. Gonioscopy

Explanation

Fluorescein dye is taken up by exposed corneal stroma where epithelium is absent, confirming an epithelial defect. The other tests evaluate tear production, intraocular pressure, and the drainage angle.

Question 47General Veterinary Ophthalmology

A dog presents with a progressive, bilateral, nonpainful corneal opacity in the axial cornea with no fluorescein uptake. Which of the following is the most likely diagnosis?

  1. Glaucoma
  2. Corneal ulcer
  3. Corneal dystrophy Correct answer.
  4. Anterior uveitis

Explanation

Corneal dystrophies are typically bilateral, nonpainful, nonulcerative opacities that do not stain with fluorescein. Ulcers, uveitis, and glaucoma are associated with pain and other signs.

Question 48General Veterinary Ophthalmology

A dog with a history of recurrent otitis externa develops Horner syndrome. Which of the following findings would be expected on ophthalmic examination?

  1. Mydriasis, an absent menace response, and a normal pupil
  2. Miosis, exophthalmos, and a normal pupil
  3. Mydriasis, ptosis, and exophthalmos
  4. Miosis, ptosis, and enophthalmos Correct answer.

Explanation

Horner syndrome results from loss of sympathetic innervation, producing miosis, ptosis, enophthalmos, and often protrusion of the third eyelid. The parasympathetic supply remains intact.

Question 49General Veterinary Ophthalmology

A dog is evaluated for a cataract and the examiner notes a dark reflex in the pupil that disappears when the light is moved. Which of the following is the most likely explanation?

  1. The lens has been surgically removed
  2. The pupil is fixed and unresponsive
  3. The eye is blind from retinal degeneration
  4. The cataract is not complete and some light still reaches the tapetum Correct answer.

Explanation

A tapetal reflex seen through a cataract indicates that some light passes through the lens to the reflective fundus. A complete cataract would eliminate this reflex.

Question 50General Veterinary Ophthalmology

A cat is presented with a slowly enlarging, pigmented mass on the iris and a history of chronic uveitis. Which of the following is the most appropriate next step?

  1. Reassurance that the lesion is benign and requires no follow-up
  2. Immediate enucleation without further evaluation
  3. Topical corticosteroid therapy alone
  4. Referral for ophthalmic examination and possible enucleation or biopsy Correct answer.

Explanation

Feline diffuse iris melanoma can mimic chronic uveitis and requires careful evaluation for malignancy and possible metastasis. Referral for advanced imaging and histopathology guides the decision for enucleation.