ACVO Veterinary Ophthalmology key terms

A blink or head withdrawal elicited by a threatening gesture toward the eye, testing the visual pathway through the cortex and cerebellum rather than a simple local reflex.

A blink or squint produced by a bright light shone into the eye, indicating that the retina and subcortical visual pathways are functional even when conscious vision is absent.

Constriction of the pupil in response to light, mediated by the retina, optic nerve, pretectal nucleus, and oculomotor parasympathetic fibers; the consensual response is tested in the opposite eye.

A test in which light is alternated between eyes to detect a relative afferent pupillary defect, revealing asymmetric retinal or optic nerve disease by paradoxical dilation of the illuminated pupil.

A strip of filter paper placed in the lower conjunctival fornix to measure tear production over one minute; values below roughly 15 mm/min suggest keratoconjunctivitis sicca.

A water-soluble orange dye instilled on the eye that fluoresces green under cobalt blue light, highlighting corneal epithelial defects, ulcers, and certain nasolacrimal patency findings.

Measurement of intraocular pressure using instruments such as applanation or rebound devices; normal canine values are roughly 10 to 20 mmHg and elevation supports glaucoma.

Visual examination of the iridocorneal drainage angle, often with a specialized lens, used to classify glaucoma as open-angle or angle-closure and to screen predisposed breeds.

Examination using a focused light beam and magnification to localize lesions within the cornea, anterior chamber, lens, and other anterior segment structures by depth.

Fundus examination using a condensing lens and a light source to produce an inverted, magnified aerial image, allowing wide-field viewing of the retina and optic disc.

Recording of the retina's electrical response to a standardized light stimulus, used to assess retinal function and to screen for inherited retinal degenerations before ophthalmoscopic changes appear.

The reflective, often colorful region of the inner eye containing the tapetum lucidum, which enhances dim-light vision and whose appearance varies markedly among species and breeds.

A condition in which the two pupils are of unequal size, which may reflect ocular disease, neurologic lesions, or pharmacologic effects and requires localization of the cause.

A triad of miosis, ptosis, and enophthalmos with protrusion of the third eyelid, caused by interruption of sympathetic innervation to the eye at any level.

A defect in the corneal epithelium, often with stromal loss, that may be superficial or deep and is detected with fluorescein staining; deep ulcers risk perforation.

A deep corneal ulcer in which the stroma is lost and only Descemet membrane remains, appearing as a clear bulge and carrying a high risk of rupture.

Rapid enzymatic softening and melting of corneal stroma, often associated with infection or tear deficiency, that can progress to perforation within hours without aggressive treatment.

Inflammation of cornea and conjunctiva caused by inadequate tear production or quality, producing dryness, discharge, and corneal changes; diagnosed with a low Schirmer tear test.

Abnormal composition or stability of the tear film despite adequate volume, often linked to meibomian gland disease or mucin deficiency, producing signs of dryness.

A group of optic neuropathies characterized by elevated intraocular pressure and progressive retinal ganglion cell loss, causing blindness if untreated; primary forms are strongly breed associated.

Inflammation of the uveal tract, including iris, ciliary body, and choroid, that presents with pain, miosis, aqueous flare, and hypotony and may be immune-mediated, infectious, or neoplastic.

A hazy appearance in the anterior chamber caused by protein leakage from inflamed uveal vessels, detected with a slit beam and indicating breakdown of the blood-aqueous barrier.

An adhesion of the iris to the cornea (anterior) or to the lens (posterior) that may follow uveitis and can obstruct aqueous flow or distort the pupil.

An opacity of the lens that may be inherited, diabetic, traumatic, or age-related; location and extent determine visual significance and suitability for surgical removal.

Complete displacement of the lens from its normal position due to zonular rupture, which may obstruct the pupil or cause secondary glaucoma; primary forms are inherited in some terrier breeds.

A group of inherited, bilateral, progressive retinal degenerations causing vision loss, often with hyperreflective tapetal changes and retinal vessel attenuation in later stages.

An inherited developmental disorder of the eye in herding breeds featuring choroidal hypoplasia, with possible coloboma and retinal detachment; screening is a core CAER activity.

A congenital defect of ocular tissue, typically at the optic nerve or choroid, appearing as a focal area of absent tissue and sometimes predisposing to retinal detachment.

The Companion Animal Eye Registry screening exam performed by certified ophthalmologists to document breed-relevant ocular disease and inform breeding decisions.

The presence of extra eyelashes arising from the meibomian gland orifices that may abrade the cornea and cause discomfort, often inherited in certain breeds.

A cilium emerging through the palpebral conjunctiva and directed toward the cornea, producing a focal ulcer and significant pain; treatment is surgical removal.

Inward rolling of the eyelid margin so that hair contacts the ocular surface, causing irritation and corneal injury; a common inherited conformation problem in many breeds.

Outward rolling or eversion of the eyelid margin that exposes conjunctiva, predisposes to exposure and conjunctivitis, and is often a breed-related conformational trait.

A sebaceous gland within the eyelid tarsus that secretes the lipid layer of the tear film, helping to limit evaporation and maintain tear film stability.

The space between the cornea and the iris filled with aqueous humor, examined for cells, flare, and hemorrhage and central to assessing uveitis and glaucoma.

The intraocular entry point of the optic nerve, visible on fundoscopy, whose color, elevation, and margin are assessed for signs of neuritis, glaucoma, or papilledema.

Widening of the pupil by relaxation of the iris sphincter and contraction of the dilator, achieved pharmacologically with mydriatics for fundus examination or to relieve uveal spasm.

A short-acting anticholinergic mydriatic instilled topically to dilate the pupil for fundus examination, with effects lasting only a few hours.

Signs from systemic absorption of topical atropine, including dry mouth, tachycardia, dilated pupils, ileus, and behavioral change, particularly in small patients.

Separation of the neurosensory retina from the underlying retinal pigment epithelium, producing acute vision loss and appearing as a raised, folded, or non-tapetal area.

A disorder of autonomic ganglia causing widespread sympathetic and parasympathetic dysfunction, with ocular signs including mydriasis, reduced tear production, and absent pupillary reflexes.