Ophthamology Flashcards
Commonly available and projects light of adequate brightness to effectively assess cranial nerve function. LED lights are discouraged as they can harm the retina
Finoff Transilluminator
Topical anitcholinergic that has a short duration of action (2-4 hours) used to facilitate examination of the posterior segment of the eye by dilating the pupil
Tropicamide
Tests for an intact affront trigeminal nerve (CN V) and efferent facial nerve (CN VII). Medial and lateral aspect of eyelid needs to be touched as these areas are inner gated by two distinct branches of trigeminal nerve.
Palpebral reflex
Evaluates for an intact affect optic nerve (CN II), cortical vision processing, and intact efferent (CN VII) by creating a menacing gesture near the eye and eliciting a blink response. Young animals develop the response between 12-16 weeks
Menace response
Tests for intact affront (CN II) and efferent oculomotor nerve (CN III) and is elicited by a bright light source observing constitution of pupil
Pupillary light reflex (PLR)
Evaluates an intact affront (CN II) and efferent facial nerve (CN VII) and is elicited using a very bright light source placed close to the eye. You should see your patient blink or move away from the light.
Dazzle reflex
Used to evaluate an intact peripheral and central vestibular apparatus including CN VIII, II, IV, and VI by briskly moving the patients head up and down observing eye movement.
Oculocephalic reflex
Assesses for an intact afferent CN V and efferent CN VI and VII by touching the corneal surface and looking for globe retraction
Corneal reflex
Nasolacrimal patency can be confirmed by observing fluorescein stain emerging from the nostril. False negatives are common
Jones test
Stains that can be used to highlight abnormalities of the tear film, corneal epithelium or conjunctival epithelium.
Rose bengal and lissamine green
Normal eye pressure with tonometry in dogs and cats
12-18mmHg
When eye pressures are greater than 25 mmHg accompanying vision loss
Glaucoma
Reduces the intraocular pressure via a break down of the blood ocular barrier. Differences of pressure >8mmHg between eyes is considered abnormal and can be helpful in diagnosing this
Uveitis
Refers to everything that supports the eye such as the orbit, periocular skin, eyelids, third eyelid, conjunctiva
Adnexa
Most commonly used to discriminate dark funds lesions were blood or hemorrhage is equivocally present. Hemorrhage will appear black
Red free light (green on direct ophthalmoscope)
On off switch used to adjust light intensity on the direct ophthalmoscope
Rheostat
The higher this is the greater the refraction of light off the lens and greater field of view during indirect exam. This is inversely related to the length of the focal point.
Diopter
When selecting a lens for indirect exams the examiner balances these two factors
Field of view and magnification
Protrusion or anterior displacement of the globe relative to it’s normal position within the orbit. Caused by space occupying orbital lesions
Exophthalmos
Common in working dogs and dogs who are prone to chewing ons ticks. Signs include acute, painful, unilateral exophthalmos. Dogs often febrile and show leukocytosis on CBC
Retrobulbar cellulitis/ Abscessation
Caused by leakage of ALI a from the gland or duct with subsequent inflammation and fibrous tissue reaction
Zygomatic salivary gland mucocele
Typically found in younger dogs and can cause unilateral or bilateral exophthalmos. Masseter and temoralis muscles are typically swollen and painful when palpated. Type IIM fiber autoantibodies found with biopsy is diagnosic
Masticatory muscle myositis
Often occurs in Golden retrievers and Labs. Classic bilateral exophthalmos with prominent scleral showing
Extraocular myositis
Abnormal recession of the eye within the orbit. Caused by pain, dehydration, emaciation, horners syndrome
Exophthalmos
Small shrunken globe caused by severe and chronic inflammation
Phthisis bulbi
Sphincter like muscle that closes the eyelid. Innervated by CN VII
Orbicularis oculi
Sphincter like muscle that closes the eyelid. Innervated by CN VII
Orbicularis oculi
Opens the upper eyelid. Innervated by CN III
Lavatory palpebral superioris
Smooth muscle that opens the upper eyelid. Innervated by GVE sympathetic efferent and responsible for ptosis seen in Horners syndrome
Mullers muscle
Fibrous plate that surrounds the tarsal or meibomian glands and provides structural rigidity to the eyelids and is important for surgical closure of lid lacerations
Tarsus
Sebaceous glands that exit in an orderly row at the eyelid margin and provide the outermost stabilizing layer of the tear film.
Meibomian glands
Inward rolling of the eyelid margin. Common in brachycephalics.
Entropion
Eyelids are not appropriately conformed to the eye as a primary condition. Unrelated to ocular surface pain
An atomic entropion
Most common surgical method of entropion repair. Important to incise close to the eyelid margin in order to effectively evert the tissue
Modified Hotz Celsus
Incomplete eyelid closure and globe coverage or the inability to completely close the eyelids. Caused by brachycephalic breeds, buphthalmos, neurological dysfunction, retrobulbar masses
Lagophthalmus
Facial hairs or eyelashes growing in a normal location but make contact with the eye. Often a result of abnormal facial conformation with prominent exposed eyes and either long facial hair or prominent nasal folds.
Trichiasis
Cilia emerging from the meibomian gland ducts.
Distichia
Common therapy for distichia. Two freeze thaw cycles are applied to palpebral conjunctiva surface until the ice ball crosses the lid margin destroying the hair follicle.
Cryoepilation
Variant of distichia. These cilia emerge through the palpebral conjunctiva and are more often associated with corneal ulceration and severe pain.
Ectopic cilia
Benign and involve the meibomian glands and secondary gland impaction. A canine eyelid tumor
Chalazion
Individual swollen meibomian glans seen when the lid margin is everted
Internal Hordeolum (meibominanitis)
Junction between palpebral and bulbar conjunctiva
Fornix
Pathological diffuse reddening of the conjunctiva. Often suggests the presence of inflammation of the ocular surface or a disorder of the tear film.
Hyperemia
Fibrovascular tissue that lies deep to the conjunctiva and superficial to the sclera. Facilitates movements of the extraocular muscles
Episclera (Tenon’s Capsule)
Refers to the pathological presence of coarse ropes vessels that travel perpendicular to the limbus and can be identified individually. Suggests deep pathology of deep structures, including glaucoma and uveitis.
Episcleral injection
Most common cause of conjunctivitis
Keratoconjunctivitis sicca
Very common in dogs <2 years of age. Many dogs dont need therapy and the condition is self-limiting. Clinical signs are blepharospasm, epiphora, and conjunctival hyperemia with discharge
Allergic conjunctivitis
Most critical test to be performed in dogs with conjunctival abnormalities
Schirmer Tear Test. Should be greater than 15mm
Used for its steroid not antibiotics. Ointment has longer retention time and dosages of 3-4 times daily up to 3 weeks are sufficient. Dont use with ulcer patients.
Neomycin Polumixin Dexamethasone
NSAID. Labeled for twice daily application. Less potent than steroids but indicated for less severe cases. Caution in cases with corneal ulcers
Diclofenac 0.1% solution
Labeled for twice daily application. Immunomodulatory drug. Indicated in chronic conjunctivitis that fails steroid therapy. Slow to reach maximal efficacy but not as bad for ulcers
Cyclosporine 0.2% ointment (Optimmune)
Rarely indicated as therapy for conjunctivitis except in cases of KCS with secondary bacterial conjunctivitis due to tear film dysfunction
Neomycin Polymixin Bacitracin
Not a common virus but can accompany severe KCS along with systemic concerns
Canine Distemper Virus
These infections closely resemble allergic conjunctivitis and can be treated similar
Adenovirus and Herpesvirus
Life long infection. 80% of infected cats the virus becomes latent in the CN V ganglion. 50% of cats shed virus during health or stress which is the most significant factor (recrudescence) Target tissue is epithelial tissue associated with ocular surface causing ulcers. Hyperemia is the predominant feature of the virus. Only this virus causes dendritic corneal ulceration and symblepharon (conjunctival adhesions). Conjunctival cytology is most useful test. Treat with 0.5% cidofovir solution and erythromycin ointment
Feline Herpesvirus 1
Etiology is unknown though suspected to be an autoimmune disease that has a relationship to FHV-1. Signs include blepharospasm, mucoid discharge, hyperemia, and raised white/yellow plaques. Finding eosinophils on cytology is diagnostic. Treat with topical steroids, immunomodulation, and supportive care
Feline Eosinophilic Keratoconjunctivitis
Common infection in shelters. Signs are conjunctival ulceration and oral ulceration. Treatment is supportive with erythromycin
Calicivirus conjunctivitis
Caused by obligate intracellular bacteria. Phases of bacterial life cycle can be resistant to treatment. Signs include chemosis (conjunctival edema). Infection does not cause ulceration. Diagnosis by intracytoplasmic inclusions within conjunctival epithelial cells on cytology. Treatment with marcrolides (erythromycin) and tetracyclines or fluoroquinolones
Chlamydial conjunctivitis
Controversial association with conjunctivitis as many healthy cats have this amongst normal ocular flora. Signs include Epiphora, chemosis, and hyperemia. Treat similar to chlamydia
Mycoplasma conjunctivitis
Outermost layer of tear film. Produced by meibomian glands and provides surface coating to the tear film preventing evaporation. Deficiency causes qualitative KCS
Lipid layer
The middle layer of the tear film. Produced by lacrimal gland and third eye lid gland. Most substantial layer and contains nutrients and anti bacterial components to protect ocular surface. Continuously flushes foreign material away from surface. Deficiencies can be measures with Schirmer Tear Test. Epiphora is a common disorder of this layer
Aqueous layer
Deepest layer of the tear film. Produced by the conjunctival goblet cells. Generates surface tension and creates interface between the corneal epithelium and the other two layers of the tear film preventing the film from sliding off the cornea.
Mucinous layer
Parts of the lacrimal drainage apparatus
Two nasolacrimal punctuation, two nasolacrimal canaliculi, lacrimal sac, and nasolacrimal duct
Deficiency of the aqueous layer of the tear film with concurrent corneal and conjunctival inflammation.
Quantitative KCS
Most common cause of KCS in which the lacrimal gland and third eyelid gland are attacked by autoantibodies.
Immune mediated quantitative KCS
Known as neurogenic KCS. Dysfunction of CN VII by inner ear infections. Causes ipsilateral dry eye and dry nose
Parasympathetic nerve lesion quantitative KCS
Deficiency of mucin or lipid layers of the tear film with concurrent corneal and conjunctival inflammation. STT is normal but same clinical signs
Qualitative KCS
Junction between the cornea and the sclera
Limbus
Thickest layer of the cornea and composed of fibrocytes which produce ordered collagen fibers arranged in lamellar. This layer is hydrophilic so retains fluorescein stain and is highly susceptible to infection
Storms
Cornea is innervated by
Ophthalmic branch of CN V
Time for epithelial ulceration of the cornea takes to heal
Less than 7 days
Time for stromal ulceration to heal
Days to weeks.
Stromal ulcer that healed with epitheliazation leaving a fluorescein negative divot in the cornea
Facet
Focal complete loss of stroma and wound contraction is not possible. Heals through vascular ingrowth and the production of granulation tissue. Takes weeks to months to heal
Descemetocele
Only cause of blue corneal opacity. Edema is result of fluid from tear film hydrating the corneal stroma. Can result from epithelial disorders and endothelial disorders
Corneal Edema
Only cause of red opacity within the cornea. Caused by new vessel formation on the cornea. Can be seen with KCS, Pannus, and uveitis
Corneal neovasculatization
Corneal opacity caused by white blood cells or abscess. This is painful
White with yellow or green hue
Corneal opacity cause by stromal scar or fibrosis. Not associated with pain
White and gray or wispy features
Corneal opacity caused by minerals or lipid. Often bright and can sparkle. Not associated with pain unless ulcer is present.
Crystalline white
Corneal opacity caused by epithelial pigment, endothelial pigment, or feline sequestrum from necrosis of corneal stroma.
Brown or black
Corneal opacity caused by accumulations of proteins and white blood cells that adhere to the endothelial surface. Small at the midpoint of the cornea and become larger and denser at the ventral cornea
Tan or greasy
Superficial corneal ulcers should heal in less than 7 days
Uncomplicated corneal ulcers
Three reasons a corneal ulcer will not heal
Indolent ulceration (boxer ulcer), Infection, and underlying irritant hasn’t been addressed.
Most common cause of feline ulcerative keratitis
FHV 1
Softening or melting of the corneal stroma due to collagenolysis. Pseudomonas aeruginosa is the most common bacterial culprit in cases where this is present. Can use chelating agents and serum to treat
Malacia
Autoimmune condition that effects German Shepherds and Greyhounds. UV light exacerbates lesions. Signs include granulation tissue and pigment. Biopsy is confirmatory. Treatment is lifelong anti-inflammatory therapy.
Pannus (Chronic superficial keratitis)
Function of the uvea
Aqueous production and formation of the blood aqueous barrier
Adhesion of iris to the cornea
Anterior synechia
Adhesion of iris to the lens
Posterior synechia
Adhesion of iris to iridocorneal angle
Peripheral Anterior Synechia
Bulging forward of the iris due to impaired passage of aqueous caused by complete posterior synechia occluding the pupil. Leads to peripheral anterior synechia and secondary glaucoma
Iris Bombe
Age related thinning of the iris stroma resulting in irregular pupillary margins, slow PLRs, and spaces in the iris
Iris Atrophy
Multiple colors within an iris or between two irides
Heterochromia irides
Developmental defect (hole) in the iris
Iris coloboma
strands of uveal tissue that originate in the iris collarette due to incomplete absorption of embryonic vascular tissue that surrounds the pupil and lens.
Persistent pupillary membranes
Inflammation of the iris and ciliary body
Anterior uveitis (Iridocyclitis)
Inflammation of the choroid
Posterior uveitis (Choroditis)
Inflammation of the entire uvea
Panuveitis
Inflammation of the uvea and intraocular contents of the eye
Endophthalmitis
Inflammation of all ocular and intraocular tissues, including the corneoscleral/fibrous tunic
Panophthalmitis
Aqueous flare is pathognomonic for this. Refers to increased turbidity of the normally clear aqueous humor due to breakdown of the blood aqueous barrier that occurs with inflammation
Uveitis
Most frequent intraocular disease in cats
Uveitis
Best topical corticosteroid choices for uveitis
1% prednisolone acetate or 0.1% dexamethasone alcohol
Immune mediated disease against melanocytes including uveal tissue. Common breeds are Akita, Samoyed, Husky. Clinical signs often acute, bilateral uveitis. Vitiligo of the eyelids, nose, feet, and lips common. Diagnosis by skin biopsy. Treat with steroids and atopica
Uveodermatologic syndrome
Pigment deposition on the lens, iris, and corneal epithelium. Eyes often red with low grade flare. There is no actual inflammation of the uvea
Pigmentary uveitis of Golden Retrievers
Most common primary intraocular tumor
Melanocytic (melanomas, melanocytomas)
Collagenous fibers that attach to the process of the ciliary body and support the lens at its equator. Suspends the lens in the pupil.
Zonules
A depression in the anterior vitreous in which the lens rests.
Patellar fossa
A transparent elastic envelop surrounding the lens. Provides insertion for lens zonules and regulates the lens shape due to elasticity.
Lens capsule
Makes up the majority of the lens and are arranged in interdigitating lamellar layers. Originate as epithelial cells and then transition to lose their nuclei and become less active and stretch the poles of the lens
Lens fibers
How most energy is provided for the lens
Metabolism of glucose via anaerobic glycolysis (Hexokinase pathway)
For this the ciliary muscles constrict (360 degrees) decreasing tension on the lens zonules and the elastic lens capsule causes the lens to take on a more spherical thickened shape
Near vision
For this the ciliary muscles relax (360 degrees) increasing tension of the lens zonules and the lens becomes a thinner flatter shape
Distance vision
Dogs and cats can only focus on
Distant objects. Closer uses smell
Abnormally small lens. May lead to lens luxation
Microphakia
Notch like defect in the lens
Lens coloboma
Developing lens fails to completely separate form the cornea resulting in an opaque cornea and lens. Often with uveal strands connecting the two structures
Peters anomaly
Most common cause of treatable vision loss in the dog
Cataracts
A hyper mature lens with liquified cortex and the solid nucleus sinks to the bottom of the capsular bag
Morgagnian cataract
Formed by the junction of the iris ciliary body and the cornea sclera.
Iridocorneal angle
Almost always due to impaired outflow
Glaucoma
Photoreceptors that function more effectively in dim light
Rods
A well vascularized neurosensory retina with a variable number of vessels extending from the optic disc in a spoke like pattern.
Holangiotic
Moderately vascular retina. Blood vessels extend medial and lateral to the optic disc (Rabbits)
Merangiotic
Very sparsely vascularized retina. Horses`
Paurangiotic
No blood vessels are present in the neurosensory retina. In avian species, a highly pigmented and pleated structure the pecten plays a role in nutrition of the inner retina
Anagiotic
Important cause of blindness in pure bred dogs
Generalized progressive retinal atrophy
Only recognized in dogs. Acute onset of blindness in hours-days. Obesity is common. Results in permanent blindness. ERG confirms diagnosis by demonstrating complete absence of photoreceptors activity
Sudden Acquired Retinal Degeneration Syndrome
Swollen fluffy optic disc. Caused by elevated intracranial and CSF pressure
Papilledema
