Veterinary Ophthalmology I

Vocabulary practice flashcards covering equipment, examination techniques, diagnostic tests, pathologies, and pharmacology in veterinary ophthalmology.

Finnoff Transilluminator

A bright, focal light source attachment used during veterinary ophthalmic examinations for direct focal illumination of ocular structures.

Slit Lamp

An ophthalmic instrument providing higher magnification and a 3D view for detailed, biomicroscopic examination of the anterior segment and ocular media.

20 D Lens

A high-diopter condensing lens used in indirect ophthalmoscopy to produce an inverted, reversed image of the ocular fundus.

Schirmer Tear Test I (STT I)

A diagnostic test measuring the aqueous component of the tear film; normal reference values are $15\text{--}25\,\text{mm/min}$ in dogs and $10\text{--}20\,\text{mm/min}$ in cats.

Precorneal Tear Film

A three-layered fluid film comprising an outer lipid layer (meibomian glands), a middle aqueous layer (lacrimal and nictitans glands), and an inner mucin layer (conjunctival goblet cells).

Fluorescein Dye

A water-soluble dye retained by hydrophilic structures (precorneal tear film and corneal stroma) used to identify corneal ulcers, assess nasolacrimal patency (Jones test), assess tear break-up time, and detect aqueous leakage (Seidel's test).

Rose Bengal

A vital diagnostic stain used to assist in the diagnosis of surface ocular injury by staining devitalised and damaged corneal and conjunctival epithelium.

Applanation Tonometry

A method of measuring intraocular pressure (IOP) by determining the force required to flatten a constant area of the cornea, commonly performed using a Tono-Pen.

Intraocular Pressure (IOP)

The fluid pressure inside the eye measured by tonometry; normal reference ranges are $10\text{--}25\,\text{mmHg}$ in dogs and $9\text{--}31\,\text{mmHg}$ in cats.

Menace Response

An acquired protective cortical response (present at $>12\text{ weeks}$ of age) where a hand moving toward the eye induces blinking; afferent pathway is CN II (optic nerve) and efferent pathway is CN VII (facial nerve).

Dazzle Reflex

A subcortical reflex present from birth in which shining a bright focal light into the eye results in bilateral eyelid blinking.

Palpebral Reflex

A protective eyelid closure reflex elicited by lightly touching the medial or lateral canthus; mediated by sensory trigeminal nerve (CN V) and motor facial nerve (CN VII).

Corneal Reflex

A sensory reflex elicited by touching the cornea with a cotton wisp, inducing blinking via CN VII and globe retraction via the abducent nerve (CN VI); afferent sensation travels via CN V.

Pupillary Light Reflex (PLR)

Pupillary constriction occurring within $2\text{--}3\text{ seconds}$ when light enters the visual axis directly, followed by consensual constriction in the contralateral eye.

Exophthalmos

Rostral displacement of a normal-sized globe within the orbit, commonly caused by retrobulbar abscess, cellulitis, orbital neoplasia, or extraocular polymyositis.

Enophthalmos

Recession of a normal-sized globe into the orbit, commonly caused by ocular pain, loss of retrobulbar fat, muscle atrophy, or Horner's syndrome.

Buphthalmos

Enlargement of the entire eyeball resulting from sustained elevated intraocular pressure (glaucoma).

Microphthalmia

A congenital abnormality characterized by a globe that is smaller than normal in size.

Phthisis Bulbi

A shrunken, non-functional, disorganized, and atrophic globe resulting from severe end-stage ocular disease or trauma.

Entropion

An inversion or rolling inward of the eyelid margin toward the globe, causing cilia to contact and irritate the cornea.

Ectropion

An eversion or outward rolling of the eyelid margin away from the globe, exposing the conjunctival mucosa.

Episcleral / Scleral Vessels

Deep vessels characterized by a large diameter, dark red color, straight trajectory, immobility over the sclera, and failure to blanch with topical epinephrine.

Conjunctival Vessels

Superficial vessels characterized by a small diameter, pink-to-light-red color, branching pattern, mobility over the globe, and blanching upon application of topical epinephrine.

Purkinje Image

A bright, clear focal reflection cast onto the corneal surface by an external light source, utilized to assess the smoothness and curvature of the tear film and cornea.

Hyphema

The presence and horizontal sedimentation of blood in the anterior chamber of the eye, typically reabsorbing within $1\text{--}3\text{ days}$ unless persistent leakage or systemic pathology exists.

Hypopyon

The accumulation of white blood cells or purulent exudate within the anterior chamber, typically forming a horizontal layer ventrally.

Iris Bombé

Anterior bowing or ballooning of the iris caused by trapped aqueous humor in the posterior chamber due to $360^\circ$ posterior synechia (seclusion of the pupil).

Anterior Uveal Cysts

Spherical, pigmented, fluid-filled structures arising from the posterior iris epithelium or ciliary body that may float freely in the anterior chamber or remain attached to the pupil margin.

Holangiotic Pattern

A retinal vascular pattern present in dogs and cats where retinal blood vessels extend throughout the entire neurosensory retina from the optic nerve head.

Tapetum Lucidum

A reflective cellular layer in the dorsal choroid (reflecting yellow, green, or blue hues) that enhances visual sensitivity in dim light; absent in albino, merle, or young animals.

Gonioscopy

The clinical examination of the iridocorneal drainage angle using a specialized diagnostic contact lens (goniolens).

Electroretinography (ERG)

A diagnostic procedure that measures and records electrical potentials generated by the retina in response to light stimuli to assess retinal function.

Dacryocystorhinogram

A contrast radiography procedure used to evaluate the patency and morphology of the nasolacrimal drainage system by injecting radiopaque dye through a lacrimal punctum.

Tropicamide

A short-acting parasympatholytic agent with a rapid onset of approximately $20\text{ minutes}$ used primarily for diagnostic pupillary dilation (mydriasis).

Atropine (Ophthalmic)

A long-acting parasympatholytic agent with an onset of approximately $45\text{ minutes}$ used therapeutically to induce mydriasis and cycloplegia; contraindicated in glaucoma, lens luxation, and dry eye.

Latanoprost

A topical prostaglandin analog used as an ocular hypotensive agent that increases uveoscleral outflow; contraindicated in feline patients.