Glaucoma

Front 1

This condition is characterized by an elevation of intraocular pressure (IOP) that results in progressive loss of retinal ganglion cells and their axons leading cause of blindness in the middle-aged dog.

Back 1

Glaucoma

Front 2

The pressure of the fluid inside the front or anterior chamber of the eye is known as the _________.

Back 2

intra-ocular pressure (IOP)

Front 3

Normal intraocular pressure for dogs & cats

Back 3

10-25 mmHg – normal (dogs & cats)

Front 4

Values of intraocular pressure for patients with glaucoma

Back 4

30 mmHg and higher

Front 5

Values of intraocular pressure that rapidly cause blindness, and are painful and cause the eye to stretch and enlarge

Back 5

above 50 mmHg

Front 6

It is the fluid that fills the anterior chamber of the eye.

Back 6

Aqueous Humor

Front 7

It is produced by the epithelial cells of the ciliary body, flows through the pupil, and circulates in the anterior chamber.

Back 7

Aqueous humor

Front 8

Optically clear, but contains various compounds such as carbohydrates, amino acids, glucose, lactate, small proteins, ions, and urea, which provide the nutritional support to the avascular lens and cornea.

Back 8

Aqueous humor

Front 9

Drainage of AH occurs through the _________ which is a complex structure formed by the junction of the peripheral iris and cornea.

Back 9

iridocorneal angle (ICA)

Front 10

This determines the intraocular pressure (IOP).

Back 10

Balance between AH formation and drainage

Front 11

It is caused by inadequate drainage of aqueous fluid when this angle, or drain, is obstructed for any reason, aqueous humor builds up inside the eye and results in increased IOP.

Back 11

Glaucoma

Front 12

Pathophysiology of glaucoma

Back 12

Front 13

Classification of glaucoma

Back 13

▫Primary glaucoma

▫Secondary glaucoma

Front 14

It is due to an inherited malformation in the ICA that, over time, leads to a reduced capacity for AH drainage without any other underlying cause. Usually begins in one eye, but in most patients it eventually involves both eyes, leading to complete blindness.

Back 14

Primary glaucoma

Front 15

This results in increased intra-ocular pressure due to disease or injury to the eye.

Back 15

Secondary glaucoma

Front 16

Types of primary glaucoma

Back 16

◾Primary open-angle glaucoma

◾Angle closure glaucoma

◾Goniodysgenesis

Front 17

The reduced outflow of aqueous humor in POAG is caused by reduction in the function of the trabecular meshwork, raising IOP

Back 17

Primary open-angle glaucoma

Front 18

Genes affected by mutation in primary open-angle glaucoma

Back 18

✔ADAMTS10 (Beagles and Norwegian Elkhounds)

✔ADAMTS17 (Petit Basset Griffon Vendéen and Basset Hound)

Front 19

It is painless and gradual development of blind spots or loss of vision over a long period of time.

Back 19

Primary open-angle glaucoma

Front 20

The aqueous does not reach the trabecular meshwork because access to the anterior chamber angle is obstructed by the iris or sometimes other tissues (some secondary glaucomas), leading to elevated IOP levels-associated with pectinate ligament dysplasia (PLD), an abnormality affecting the iridocorneal angle that has been shown to be highly heritable.

Back 20

Angle closure glaucoma

Front 21

The onset of this type of primary glaucoma is characterised by a very rapid (acute) increase in intraocular pressure, often literally overnight, that is extremely painful and frequently leads to sudden and irreversible blindness.

Back 21

closed angle glaucoma

Front 22

This is also known as Pectinate Ligament Dysplasia (PLD)

Back 22

Goniodysgenesis

Front 23

It is a congenital Iridocorneal angle abnormality in which there is a lack of fenestration of the iridocorneal angle (ICA) during development of the eye.

Back 23

Goniodysgenesis

Front 24

Breeds genetically predisposed with Open angle glaucoma

Back 24

🐶Beagle

🐶Great Dane

🐶Keeshound

🐶Norwegian Elkhound

🐶Poodle (Toy and Miniature)

🐶Samoyed

🐶Siberian Husky

Front 25

Breeds genetically predisposed with closed angle glaucoma

Back 25

🐶Akita

🐶American Cocker Spaniel

🐶Basset Hound

🐶English Cocker Spaniel

🐶English Springer Spaniel

🐶Flat Coated Retriever

🐶Golden Retriever

🐶Poodle (Toy and Miniature)

🐶Samoyed

🐶Shar Pei

🐶Welsh Springer Spaniel

Front 26

Breeds genetically predisposed with goniodysgenesis

Back 26

🐶Basset Hounds

🐶Chow Chows

Front 27

This is the most common cause of secondary glaucoma:

Back 27

✔anterior lens luxation (movement of the entire lens into the front of the eye)✔uveitis (inflammation inside the eye)✔advanced cataracts✔intraocular masses ✔trauma to the eye✔Tumors✔Anterior dislocation of lens ✔Intra-ocular bleeding✔Pigmentary glaucoma

Front 28

TRUE OR FALSE. Glaucoma in cats is usually secondary to chronic uveitis

Back 28

True

Front 29

Although primary glaucoma is less commonly seen in cats, breeds at risk include:

Back 29

🐱Siamese

🐱Burmese

🐱Persian

🐱Domestic shorthairs

Front 30

Duration of glaucoma

Back 30

▫acute

▫chronic

Front 31

It is defined as an elevation in IOP of < 24-48 hours duration. If patients are treated during this phase, vision may be salvageable.

Back 31

Acute glaucoma

Front 32

This develops after the IOP elevation is sustained for days or longer. Medical therapy may be effective at reducing the IOP, however vision cannot be regained.

Back 32

Chronic glaucoma

Front 33

Early clinical signs of glaucoma

Back 33

-sluggish to slightly dilated pupils -mild bulbar conjunctival venous congestion -early enlargement of the eye (buphthalmia)

Front 34

Classic signs of glaucoma

Back 34

 Hazy / cloudy cornea  Dilated pupil  Episcleral injection  Buphthalmos  Optic nerve cupping

Front 35

Signs of glaucoma

Back 35

✔Corneal edema

✔Dilated pupil

✔Episcleral and conjunctival blood vessel congestion

✔pain

✔blindness

✔enlargement of the globe corneal

✔insensitivity

✔cupping of the optic disc

✔thinning of the retina causing hyperreflectivity especially around the optic disc.

✔Corneal striae (Haab's striae)

Front 36

The cloudy appearance is caused by interference with the pumping mechanisms of the corneal endothelial cells.

Back 36

Corneal edema

Front 37

TRUE OR FALSE. The high pressure causes the pupil to dilate and be less responsive to light, and dilation is thought to be due to neurologic or vascular damage to the ciliary body and iris as well as impaired retinal and optic nerve function.

Back 37

True

Front 38

In this condition, the pressure elevation causes blockage of normal venous drainage and engorgement of anterior ciliary veins.

Back 38

Episcleral and conjunctival blood vessel congestion

Front 39

These are cracks in Descemet's membrane from stretching of the globe. Their presence indicates previous glaucoma regardless of the current IOP.

Back 39

Corneal striae (Haab's striae)

Front 40

TRUE OR FALSE. By the time eye enlargement, cupping of the disc, or hyperreflectivity of the retina are obvious, there is essentially no chance for return of sight.

Back 40

True

Front 41

This tool is useful in the treatment and monitoring of intraocular pressure elevations associated with the disease process.

Back 41

Tonometer

Front 42

This procedure helps determine how predisposed the remaining visual eye is to develop glaucoma when primary glaucoma is present in the other eye.

Back 42

Gonioscopy

Front 43

A special contact lens used in gonioscopy of the eye, which allows examination of the drainage angle.

Back 43

“goniolens”

Front 44

Tx for glaucoma

Back 44

✔Osmotic Diuretic: dehydrate to vitreous—used in emergency therapy only; crucial that the patient is know to be capable of producing urine prior to using osmotic diuretics.✔Miotics: increase outflow of aqueous typically by opening the drainage angle✔Carbonic Anhydrase Inhibitors: decrease production of aqueous✔Autonomic Agents: Sympathomimetic--(increases aqueous outflow; reduces aqueous humor production). ✔Beta-blockers reduce the formation of AH via their effects on beta receptors present in the ciliary body. Undesirable cardiac and respiratory effects can be seen with topical beta-blockers, including bradycardia, and bronchoconstriction. Thus, these medications should be avoided in patients with cardiovascular disease and asthma. ✔Chemical Ciliary Body Ablation / Intravitreal Gentocin Injection: indicated for blind, painful eyes. The most commonly described procedure involves an intravitreal injection of gentocin, which is aimed at pharmacologic ablation of the ciliary body. This in turn causes decreased production of aqueous.