Final: Ophthalmology - Lens, Glaucoma, Fundus Flashcards
What is the therapy for cataracts?
Topical NSAIDs and corticosteroids (to help control/prevent lens-induced uveitis)
Phagoemulsification - sx where lens is broken up using ultrasound energy and aspiration
What is the therapy for lens induced uveitis?
Topical +/- systemic anti-inflammatories
What is the etiology of lens luxation? How is it treated?
Primary: Inherited (Terrier breeds) causng abnormal degeneration of zonular ligaments; more common in dogs
Secondary: Chronic uveitits (most common in cats), trauma, chronic glaucoma (enlargement of globe can stretch/break zonular ligaments)
When is latanoprost indicated with lens instability? When is it counterindicated?
Indicated: Anterior lens luxation when surgery IS NOT possible, subluxation
C/O’d: Anterior lens luxation when surgery IS possible
Latanoprost = Miotic to trap lens
What is the term for the hardening of the lens that occurs naturally in animals and causes increased reluceny such that the lens appears cloudy? At what age is it evident in dogs and cats? Does it cause vision loss?
Nuclear sclerosis
7 yrs
Does not cause vision loss
What is a cataract?
Any opacity of the lens or lens capsule
What is used to determine where the opacity is located in the lens?
Parallax - using the appearance of one object relative to another to determine depth
Where do lens zonules attach? What are they?
Equator of the lens
Small collagen fibrils arising from ciliary body that secure the lens’ position within the eye (ligaments of the ciliary body)
What type of cataract formation is driven by osmotic effects due to entrapped sorbital (converted from glucose by aldose reductase) and fructose in the lens capsule? What animals is this type common in?
Intumescent cataract
Diabetics
When do you see an aphakic crescent?
Lens subluxation
What is the movement of the iris that occurs secondary to lens instability? What about the movement of the lens secondary to lens instability?
Iridonesis
Phacodonesis
Cataract or nuclear sclerosis:
Can see the fundus through a lens attenuation
Can see fundus around a lens attenuation
Nuclear sclerosis: Can see the fundus through a lens attenuation
Cataract: Can see fundus around a lens attenuation
What is the most common cause for cataract formation in dogs? Cats and horses?
Dogs: Inherited
Cats, Horses: Chronic uveitis
Dogs with ____ will lose rod photoreceptor function and display ____ blindness, often before developing ______.
Progressive retinal atrophy (PRA)
Night
Cataracts
Important to exclude retinal disease as an etilogy of cataract prior to pursuing cataract surgery
What are the 2 types of lens-induced uveitis? Which is more severe and how are they caused?
Phacoclastic (more severe)- caused by traumatic tears of the lens capsule
Phagolytic (milder)- leakage of lens proteins from a cataract
What is the treatment for anterior lens luxation in a visual or potentially visual eye?
First medically stabilize- decrease IOP (Mannitol, Dorzolamide)
If connot contril IOP = surgical emergency
Where is aqueous humor formed? What is its path to drainage within the eye?
Ciliary body (aided by Carbonic anhydrase)
Ciliary body -> Posterior chamber -> Pupil-> Anterior chamber -> Iridocorneal angle (or Uveoscleral angle) -> Venous drainage
What are the clinical signs associated with glaucoma?
Episcleral injection (Red eye)
Pain, Blepharospasm
Cloudy eye (Corneal edema)
Mydriasis
Impaired vision
Increased IOP (>20mmHg suspicious, >25mmHg= glaucoma)
Chronic: Optic disc cupping, Retinal degeneration, Buphthalmos, Physis bulbi
How is glaucoma classified and what are the causes? Are there breed predispositions?
Primary: most commonly caused by primary angle closure (goniodysgenesis); usually bilateral, common in Cocker Spaniels, Basset Hounds, Labradors
Secondary: associated w/ other ocular or systemic abnormalites; most common cause= uveitits + hyphema, also neoplasia and lens luxation
What are the most common medical therapies for glaucoma?
Latanoprost 0.005% - most effective for K9 primary glaucoma; increases uveoscleral outflow; use in an emergency as well as long-term
Dorzolamide 2% (Carbonic anhydrase inhibitors)- decreases aqueous production; emergency and long-term
IV Mannitol 20%: use when latanoprost and dorzolamide are ineffective
What are the surgical therapies for glaucoma?
Gonioimpant- increase aqueous outflow
Ciliary body ablation/ Cyclodestruction- decrease aqueous production
Would probably refer for these
What are the salvage procedures for blind and painful eyes?
Enucleation
Evisceration and prosthesis
Cilicary body ablation (intravitreal gentocin)
The optic nerve is extremely sensitive to increased IOP. With glaucoma the optic nerve will lose _____ and will be displaced _______, displaying a _____ appearance.
Myelin
Posteriorly
Cupped
What is the only cause of buphthalmos? What is it?
Glaucoma
Enlargement of the globe
What are the fractures of Descemet’s membrane called that occur secondary to buphthalmos and stretching of the globe, which can be seen as subtle white streals coursing across the cornea?
Haab’s Striae
What is gonidysgenesis?
Abnormal iridocorneal angle conformation in which the angle is narrowed or closed
What is the use of a goniolens, applied to the surface of the eye which allows light to bend into the iridocorneal angle and facilitates examination?
Gonioscopy
What are the 2 halmarks of glaucoma?
Increased IOP
Vision loss (from damage to the optic nerve and retina)
When measuring IOP with tonometry you obtain the values 25mmHg, 13mmHg, and 17mmHg. Which is the correct IOP?
13 mmHg (lowest IOP= most accurate)
T/F: Lack of pigment in the Retinal Pigmented Epithelium (RPE) is a normal variation of the fundus.
True
Common in blue-eyed dogs
What species have a holangiotic (completely vascularized) retina?
Canine
Feline
Bovine
Caprine
Ovine
What are the hallmarks of fundus disease (6) ?
- Retinal hemorrhage
- Retinal detachment
- Vascular changes (attenuation, dilation, tortuosity)
- Altered tepetal reflectivity (Hyper or Hypo)
- Altered pigmentation (Focal or patchy)
- Altered optic head appearance
What are some causes of retinal hemorrhage?
Anemia
Systemic hypertension
Hyperviscosity
Diabetes mellitus
Chorioretinitis
Coagulopathy
Trauma
Retinal detachment
T/F: Retinal hemorrhage can be localized. When it is pre-retinal it is known as a keel boat. When within a nerve fiber layer it will be flame-shaped. When it is within the retina it is dot-blot formed. When it is sub-retinal it is diffuse and irregular.
True
What are some causes of retinal detachment?
Vitreous disease
Congenital malformations
Lens luxations
Neoplasia
Chorioretinitis
Trauma
Hypertension/Vascular disease (common in practice)
What are the 2 types of retinal detachment? Which is treated medically and which surgically? What ‘sign’ is seen on ultrasound when retinal detachment occurs?
Bullous- medical treatment (common early sign of feline hypertensive retinopathy); Rx= Amlodipine
Rhegmatogenous- surgical (Common in Shih Tzu)
Seagull sign
What etiology/type of retinal degeneration causes gradual vision loss? Which causes sudden vision loss?
Progressive retinal atrophy (PRA) or Feline central retinal degeneration = gradual
Sudden acquired retinal degeneration syndrome (SARDS), Enrofloxacin in cats= sudden (looks like Cushing’s but suddenly blind)
How do you distinguish an active from an inactive chorioretinitis lesion?
Active: poorly circumscribed, raised, gray-white areas of edema or cellular infiltrate
Inactive: well circumscribed, flat, scarring
PLR abnormalities, peripheral blindness, hyperemia, peripapillar edema, and retinal detachment are associated with which condition?
Optic neuritis
(DDx: CDV, toxo, Neosporosis, Ehrlichia, Mycoses, GME, lymphoma)
