Final: Ophthalmology - Lens, Glaucoma, Fundus

Question 1

What is the therapy for cataracts?

Answer 1

Topical NSAIDs and corticosteroids (to help control/prevent lens-induced uveitis)

Phagoemulsification - sx where lens is broken up using ultrasound energy and aspiration

Question 2

What is the therapy for lens induced uveitis?

Answer 2

Topical +/- systemic anti-inflammatories

Question 3

What is the etiology of lens luxation? How is it treated?

Answer 3

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)

Question 4

When is latanoprost indicated with lens instability? When is it counterindicated?

Answer 4

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

Question 5

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?

Answer 5

Nuclear sclerosis

7 yrs

Does not cause vision loss

Question 6

What is a cataract?

Answer 6

Any opacity of the lens or lens capsule

Question 7

What is used to determine where the opacity is located in the lens?

Answer 7

Parallax - using the appearance of one object relative to another to determine depth

Question 8

Where do lens zonules attach? What are they?

Answer 8

Equator of the lens

Small collagen fibrils arising from ciliary body that secure the lens’ position within the eye (ligaments of the ciliary body)

Question 9

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?

Answer 9

Intumescent cataract

Diabetics

Question 10

When do you see an aphakic crescent?

Answer 10

Lens subluxation

Question 11

What is the movement of the iris that occurs secondary to lens instability? What about the movement of the lens secondary to lens instability?

Answer 11

Iridonesis

Phacodonesis

Question 12

Cataract or nuclear sclerosis:

Can see the fundus through a lens attenuation

Can see fundus around a lens attenuation

Answer 12

Nuclear sclerosis: Can see the fundus through a lens attenuation

Cataract: Can see fundus around a lens attenuation

Question 13

What is the most common cause for cataract formation in dogs? Cats and horses?

Answer 13

Dogs: Inherited

Cats, Horses: Chronic uveitis

Question 14

Dogs with ____ will lose rod photoreceptor function and display ____ blindness, often before developing ______.

Answer 14

Progressive retinal atrophy (PRA)

Night

Cataracts

Important to exclude retinal disease as an etilogy of cataract prior to pursuing cataract surgery

Question 15

What are the 2 types of lens-induced uveitis? Which is more severe and how are they caused?

Answer 15

Phacoclastic (more severe)- caused by traumatic tears of the lens capsule

Phagolytic (milder)- leakage of lens proteins from a cataract

Question 16

What is the treatment for anterior lens luxation in a visual or potentially visual eye?

Answer 16

First medically stabilize- decrease IOP (Mannitol, Dorzolamide)

If connot contril IOP = surgical emergency

Question 17

Where is aqueous humor formed? What is its path to drainage within the eye?

Answer 17

Ciliary body (aided by Carbonic anhydrase)

Ciliary body -> Posterior chamber -> Pupil-> Anterior chamber -> Iridocorneal angle (or Uveoscleral angle) -> Venous drainage

Question 18

What are the clinical signs associated with glaucoma?

Answer 18

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

Question 19

How is glaucoma classified and what are the causes? Are there breed predispositions?

Answer 19

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

Question 20

What are the most common medical therapies for glaucoma?

Answer 20

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

Question 21

What are the surgical therapies for glaucoma?

Answer 21

Gonioimpant- increase aqueous outflow

Ciliary body ablation/ Cyclodestruction- decrease aqueous production

Would probably refer for these

Question 22

What are the salvage procedures for blind and painful eyes?

Answer 22

Enucleation

Evisceration and prosthesis

Cilicary body ablation (intravitreal gentocin)

Question 23

The optic nerve is extremely sensitive to increased IOP. With glaucoma the optic nerve will lose _____ and will be displaced _______, displaying a _____ appearance.

Answer 23

Myelin

Posteriorly

Cupped

Question 24

What is the only cause of buphthalmos? What is it?

Answer 24

Glaucoma

Enlargement of the globe

Question 25

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?

Answer 25

Haab's Striae

Question 26

What is gonidysgenesis?

Answer 26

Abnormal iridocorneal angle conformation in which the angle is narrowed or closed

Question 27

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?

Answer 27

Gonioscopy

Question 28

What are the 2 halmarks of glaucoma?

Answer 28

**Increased IOP** **Vision loss** (from damage to the optic nerve and retina)

Question 29

When measuring IOP with tonometry you obtain the values 25mmHg, 13mmHg, and 17mmHg. Which is the correct IOP?

Answer 29

13 mmHg (**lowest IOP= most accurate)**

Question 30

T/F: Lack of pigment in the Retinal Pigmented Epithelium (RPE) is a normal variation of the fundus.

Answer 30

True ## Footnote *Common in blue-eyed dogs*

Question 31

What species have a holangiotic (completely vascularized) retina?

Answer 31

Canine Feline Bovine Caprine Ovine

Question 32

What are the hallmarks of fundus disease (6) ?

Answer 32

1. Retinal hemorrhage 2. Retinal detachment 3. Vascular changes (attenuation, dilation, tortuosity) 4. Altered tepetal reflectivity (Hyper or Hypo) 5. Altered pigmentation (Focal or patchy) 6. Altered optic head appearance

Question 33

What are some causes of retinal hemorrhage?

Answer 33

Anemia Systemic hypertension Hyperviscosity Diabetes mellitus Chorioretinitis Coagulopathy Trauma Retinal detachment

Question 34

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.

Answer 34

True

Question 35

What are some causes of retinal detachment?

Answer 35

Vitreous disease Congenital malformations Lens luxations Neoplasia Chorioretinitis Trauma **Hypertension/Vascular disease (common in practice)**

Question 36

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?

Answer 36

**Bullous-** medical treatment (*common early sign of feline hypertensive retinopathy);* **Rx= Amlodipine** **Rhegmatogenous**- surgical *(Common in Shih Tzu)* **Seagull sign**

Question 37

What etiology/type of retinal degeneration causes gradual vision loss? Which causes sudden vision loss?

Answer 37

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)*

Question 38

How do you distinguish an active from an inactive chorioretinitis lesion?

Answer 38

_Active:_ poorly circumscribed, raised, gray-white areas of edema or cellular infiltrate _Inactive:_ well circumscribed, flat, scarring

Question 39

PLR abnormalities, peripheral blindness, hyperemia, peripapillar edema, and retinal detachment are associated with which condition?

Answer 39

Optic neuritis (DDx: CDV, toxo, Neosporosis, Ehrlichia, Mycoses, GME, lymphoma)