ACVO Veterinary Ophthalmology cheat sheet

The tear film has three layers: lipid (meibomian glands), aqueous (lacrimal and third eyelid glands), and mucin (goblet cells); deficiency of any layer causes qualitative or quantitative dry eye.

Normal Schirmer tear test I values in dogs are approximately 15-25 mm/min; values below 10 mm/min support keratoconjunctivitis sicca, and below 5 mm/min is strongly diagnostic.

Intraocular pressure in normal dogs is roughly 10-25 mmHg by applanation or rebound tonometry; values above 25-30 mmHg warrant glaucoma investigation, and below 10 mmHg suggests uveitis or globe rupture.

The menace response is a learned cortical response that is absent in very young puppies and can be absent in normal cats; pupillary light reflex tests the subcortical pathway and is present earlier.

Direct pupillary light reflex afferent limb is the optic nerve (CN II) and efferent limb is the oculomotor nerve (CN III); a swinging flashlight test localizes the lesion.

The corneal reflex afferent limb is the ophthalmic branch of the trigeminal nerve (CN V) and efferent limb is the facial nerve (CN VII).

Dazzle reflex afferent is CN II and efferent is CN VII; it is subcortical and can persist when the menace response is absent from cortical disease.

Aqueous humor is produced by the ciliary body and drains mainly via the iridocorneal angle through the pectinate ligament into the scleral venous plexus in dogs.

The tapetal fundus reflects light via the tapetum lucidum; the nontapetal region is pigmented, and the optic disc is located in the nontapetal fundus in dogs and cats.

Topical atropine (1%) is a muscarinic antagonist causing mydriasis and cycloplegia; systemic absorption via the nasolacrimal duct can cause dry mouth, tachycardia, and ileus, especially in small patients.

Tropicamide (0.5-1%) produces rapid, short-acting mydriasis useful for fundic examination; duration is roughly 4-6 hours versus 1-3 days for atropine.

Timolol 0.5% is a nonselective beta-adrenergic antagonist that reduces aqueous production; it is contraindicated in patients with cardiac disease or asthma because of systemic beta blockade.

Latanoprost, a prostaglandin F2-alpha analog, increases uveoscleral outflow and is potent for IOP reduction but can cause conjunctival hyperemia and miosis-associated side effects.

Pilocarpine is a direct muscarinic agonist that causes miosis and increases trabecular outflow; it can cause ocular irritation and systemic cholinergic signs.

Topical corticosteroids reduce inflammation but delay corneal epithelial healing and increase risk of corneal melting and fungal infection when the cornea is ulcerated.

Fluorescein dye is used to detect corneal epithelial defects; it stains exposed stroma but not intact epithelium, and Seidel testing detects aqueous leakage.

Systemic ivermectin toxicity in dogs with MDR1/ABCB1 mutation causes mydriasis, hypersalivation, ataxia, and tremors from GABA-gated chloride channel overactivity.

Topical fluoroquinolones and aminoglycosides are concentration-dependent in the tear film; frequent application improves efficacy against susceptible corneal pathogens.

Keratoconjunctivitis sicca presents with mucoid discharge, corneal vascularization, and low Schirmer tear test values; treatment includes tear stimulants such as cyclosporine or tacrolimus.

Corneal ulcers are classified by depth: superficial loss of epithelium, deep stromal loss, and descemetocele where stroma is lost to Descemet membrane; descemetocele requires surgical stabilization.

Indolent (boxer) ulcers have loose epithelial edges, fail to heal in 7-10 days, and respond to debridement, grid keratotomy, or diamond burr superficial keratectomy.

Uveitis signs include miosis, aqueous flare, hypopyon, ciliary spasm, and hypotony; treatment targets underlying cause plus topical corticosteroids and atropine.

Primary angle-closure glaucoma in dogs presents with a fixed dilated pupil, episcleral congestion, corneal edema, and IOP often above 40 mmHg; it is an emergency.

Cataracts are graded by extent (incipient, immature, mature, hypermature); phacoclastic uveitis results from lens capsule rupture and lens protein exposure.

Entropion is inward rolling of the eyelid margin causing trichiasis and corneal irritation; correction may require temporary tacking in young dogs before definitive surgery.

Prolapsed third eyelid gland (cherry eye) is treated by gland replacement rather than excision to preserve tear production and reduce risk of keratoconjunctivitis sicca.

Sudden acquired retinal degeneration syndrome causes acute blindness with mydriasis and absent menace in older dogs; fundus may appear normal initially and electroretinography confirms loss of function.

CAER stands for Companion Animal Eye Registry, operated by the American College of Veterinary Ophthalmologists, and screens breeding dogs for heritable eye disease.

CAER examinations are performed by board-certified veterinary ophthalmologists and generate a standardized form with breed-specific and diagnosis-specific coding.

CAER screening is done with indirect ophthalmoscopy, slit-lamp biomicroscopy, and tonometry; results are recorded for registry submission and breeding decisions.

The ACVO Genetics Committee maintains breed-specific recommendations for screening age and frequency, and some breeds require examination at defined intervals.

Collie eye anomaly is an autosomal recessive disorder associated with a NHEJ1 gene variant causing choroidal hypoplasia, coloboma, and retinal detachment.

Progressive retinal atrophy in many breeds is inherited and progressive; the prcd form is autosomal recessive and genetic testing guides breeding decisions.

Multifocal retinal dysplasia and other inherited developmental anomalies are recorded on CAER forms and may be considered breeding exclusions depending on breed guidance.

Persistent hyperplastic tunica vasculosa lentis and persistent hyperplastic primary vitreous are congenital anomalies that can appear on CAER examinations in predisposed breeds.

CAER results are reported as normal, affected, or breeder option, and the registry database supports tracking of heritable ocular disease prevalence over time.