2. Chapter 4 Common Diseases of Companion Animals
Ophthalmic Diseases
Chapter 4
Common Diseases of Companion Animals

3. Ophthalmic Diseases
The cornea has no blood supply but has nerve endings. The outer layer is corneal epithelium which heals quickly when damaged. Descemet’s membrane is the innermost membrane of the cornea. The choroid contains blood vessels, lymph, and pigment. It stretches around to the ciliary bodies which make aqueous humor in the anterior chamber. The ciliary bodies have processes on them that attach to the lens that push or pull on the lens when focusing an image.

4. Anatomy of the eye:
Sclera: white portion of eye, contains fibrous tissue, which helps maintain shape.
Cornea: has no blood supply but has nerve endings.
Corneal epithelium: The outer layer, which heals quickly when damaged.
Descemet’s membrane is the innermost membrane of the cornea.
Choroid contains blood vessels, lymph, and pigment. It stretches around to the ciliary bodies which make aqueous humor in the anterior chamber.
Ciliary bodies have processes on them that attach to the lens that push or pull on the lens when focusing an image.
Descemet is the inner surface of the cornea.
Anterior chamber: space between the cornea and iris. It is filled with watelike substance that is continually being produced in the choroid. This substance is responsible for ocular pressure.
Ciliary bodies: At the anterior portion of the choroid. They are in charge of the size of the pupil.

5. Anatomy continued: Iris: The colored part of the eye
Pupil: Passageway for light from anterior portion of the eye to the retina
Lens: Behind the pupil
Retina: a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain.
Lens: Compressions of lens fibers with age results in gray cloudiness in older animals. This is an aging change that is different from thickening lens that results from other dz, such as cataracts or diabetes mellitus.
Retina: Where visual images are formed.

6. Diseases of accessory structures:
These are diseases that involve :
Eyelids
Conjunctiva
Tear ducts
Third eyelid
Lacrimal gland
Included red eye: could be allergies.
Discharge: due to trauma, need to look for cuts or ulcers in eye.
Trauma or infection of these tissues are the common reasons we see these cases in an animal hospital
Signs usually consist of included red eyes, blepharospasm, and ocular discharge

7. Conjunctivitis Causes of conjunctivitis Allergies
CONJUNCTIVA: pink tissue that lines the inner surface of the eyelids and covers the front portion of the eyeball except for the cornea
Causes of conjunctivitis
Allergies
Poor anatomy (ectropion, entropion)
Bacterial infection secondary to:
Injury
↓Tear production
Foreign body
Respiratory disease (Herpes virus, calicivirus, mycoplasma, chlamydia)
Highly vascular tissue
Ectropion: eyelids flip out
Entropion: eyelids flip in
Bacterial conjunctivitis in dogs: due to disruption of normal tear production, injury, or foreign body.
Respiratory refers to cats: FHV is the most common cause of bilateral conjunctivitis seen in kittens and is combination with respiratory symptoms.
Have seen mild cases with Calicivirus and mycoplasma bacteria.

8. Redness(hyperemia), chemosis(congested/swollen),
Presence or absence of other signs of upper respiratory tract diseases.
Redness(hyperemia), chemosis(congested/swollen),
painful, ocular discharge

9. Conjunctivitis Diagnosis Determine the primary disease:
Complete physical exam is needed
Rule out a foreign body
Rule out ‘dry eye’ in chronic cases
Schirmer tear test
Numb the eye and explore the conjunctiva with a dry q-tip to look for FB
Below 10 on STT is indicative of decreased tear production
Physical exam: shows any other indications that something happened with the eye.

10. SCHIRMER TEAR TEST
The Schirmer tear test measures a dog's tear production.
A special test strip is placed into a dog's lower eyelid (or conjunctival sac), making contact with a dog's cornea
Once the strip is in a dog's eye, the dog's eye is closed shut and is left there for one minute
If a dog produced any tears, the paper will absorb them and indicate the quantity of tears produced.
The test strip has numbers on it like a ruler.
The Schirmer test's measurements are determined by how much color is seen on the tear-stained paper

11. SCHIRMER TEAR TEST
The Schirmer tear test usually isn't painful for a dog, especially if his eye has been numbed before the test. The test can be somewhat uncomfortable for a dog if his eyes are already in pain. Some veterinarians will administer a topical anesthetic to numb the eye in order to prevent tearing due to the irritation from the strip of paper. Numbing the eye, however, can alter the test results

12. Conjunctivitis Treatment Client info Topical antibiotic ointment
neomycin/bacitracin/polymyxin B (BNP or triple antibiotic)
Antibiotic ointment w/ cortisone (only if no corneal ulcer present)
Client info
Keep medial canthus of eye clean (warm water, clip hair)
Vaccinate kittens to prevent URI
Do not touch eye with applicator of eye ointment
Discard unused medication
Fluffy faced dogs and grooming
Ointments provide longer tissue contact than solutions.
Throw out eye medications once finished, don’t risk using expired or contaminated eye creams/solutions.
Steroids will delay the healing process. It would take longer for the ulcer to go away and could result in infections.

13. Epiphora EPIPHORA: excessive tearing Causes: Overproduction of tears
Ocular pain, irritation from hair, etc.
Faulty drainage of tears by lacrimal system
Blockage of duct
Blockage of puncta
Imperforate puncta (no opening)
Overproduction of tears is always a result of ocular pain or irritation. It is a clinical sign, not a disease.
Blockage of lacrimal duct by swelling or inflammatory cells, imperforate puncta, or trauma.
An imperforate lacrimal punctum is a congenital disorder of dogs involving the lack of an opening to the tear duct in the conjunctiva
Located on medical canthus of eye (there are 2). Both can be closed.

14. Normally, a thin film of tears is produced to lubricate the eyes and the excess fluid drains into the lacrimal or tear ducts, which are located in the medial canthus or corner of the eye next to the nose. The tear ducts drain tears into the back of the nose and the throat.
With this condition, there is either blockage that is causing an excess amount of tears to come out, or they are actually producing an excessive amount of tears.

15. Epiphora Watery eyes Staining of fur around eyes
Accumulation of hair or face folds may cause the tears to stay on the face. This could result in entropion or ectropion.
Watery eyes
Staining of fur around eyes

16. Epiphora Diagnosis Physical exam
Fluorescein dye test for patency of duct
Dye draining at nose indicates duct is patent
Patent means that the lacrimal duct is fine.

17. EPIPHORA Treatment Treat primary cause Flush lacrimal ducts if blocked
Surgically open imperforate puncta
Topical antibiotic ointment for infection
Keep hair trimmed around eyes
Imperforate puncta: lack of an opening to the tear duct

18. EPIPHORA Client info Staining due to pigment in tears can be resolved
Some dogs have life-long problem
It will be flushed with a small amount of saline
FLUSHING THE NASOLACRIMAL DUCT

19. EPIPHORA
Client info
Staining due to pigment in tears can be resolved with topical and/or medical management
Some dogs have life-long problem due to chronic infection or abnormal conformation

20. Eyelid disease: They protect the globe
Help remove debris from eye , shade the eye during sleep, and spread lubricating secretions over the eye
Eyelashes project from the border of each eyelid
Blepharitis:
Swelling of the eyelids
Causes: Exposure to allergens, nutritional deficiencies, viral infections, or dermatitis from any cause
C/S: Edema of lids with redness, discharge, and spasms of the eyelid
Treatment: Warm compresses & Corticosteroids
Warm compresses to help with swelling
Blepharitis: inflammation of the eyelids

21. Entropion: eyelids that roll in against the cornea
Causes
Congenital
Nonspastic: Trauma causing scarring and distortion of lid
Spastic: Severe blepharospasm from pain
Signs
Epiphora (excessive watering of the eye)
Chemosis (swelling)
Conjunctivitis
Pain
Corneal ulceration (±)
Photophobia (sensitive to light)
Entropion is an abnormality of the eyelids in which the eyelid "rolls" inward. This inward rolling often causes the hair on the surface of the eyelid to rub against the cornea (outer part of the eyeball) resulting in pain, corneal ulcers or corneal erosions
Common in dogs, less common in cats.
Acquired Nonspastic: caused by surgery or trauma
Acquired Spastic : usually secondary to corneal lesions, conjunctival inflammation, or both. Seen more commonly in cats.

23. Entropion Treatment Surgical correction is treatment of choice
Temporary mattress suture to evert eyelid (young animal)
Lateral canthoplasty to shorten eye lid
Hotz-Celsus: Remove elliptical piece of tissue from under eye

24. Hotz-celsus technique
6 minutes
Under-correction requires a repeated surgery to rectify the problem.
Over-correction can lead to ectropion, with conjunctivitis due to exposure

25. Ectropion Causes Signs Treatment Congenital
Over-correction of entropion
Signs
Conjunctivitis
Epiphora (excessive watering of the eye)
Keratitis (corneal inflammation/scarring)
Treatment
Surgery to shorten eye lid
Natural breed characteristic in basset hounds, bloodhounds, cocker spaniels, English bulldogs, and saint bernards.

27. Hypertrophy and Prolapse of 3rd eyelid gland
Also known as cherry eye

28. Prolapse of Nictitans Gland (Cherry Eye)
Nictitating membrane(3rd eyelid) is a protective structure and produces ~50% of tears
Signs
Young dog (<2 y)
Epiphora
Usually no pain
3rd eyelid: protects eye, covers the eye to protect I from injury.
medial canthus is filled with the red, swollen, nictitating membrane, which resembles a small cherry.
The cause is unknown, although seen in some specific breeds: Basset hounds, beagles, Boston terriers, and cocker spaniels.

29. Prolapse of Nictitans Gland (Cherry Eye)
Diagnosis
Rule out tumor in older dogs and cats
Treatment
Sx to remove gland is an option , but not recommended
Suture back in place
Hypertrophy only occurs in dogs. If this is seen in cats or older dogs , the cause is usually due to neoplasia.
Removal of the gland is not recommended because it could predispose the patient to Dry eye. The only reason to do this procedure would be if the patient had neoplasia.
Suture back refers to a tack down procedure. Without surgery, the patient could suffer from corneal damage which could lead to blindness.

30. Glaucoma
GLAUCOMA: increased intraocular pressure due to excess production or decreased drainage of aqueous humor
aqueous humor provides nourishment to lens and cornea
Normally, the amt of fluid produced = amt of fluid leaving eye
Normal intraocular pressure: Dog/Cat—12-22 mm Hg
Signs
Ocular pain
Corneal edema
Dilated pupil (unresponsive to light)
Blind (±)
In a healthy eye: the production of aqueous fluid is equal to the amount leaving the eye and the IOP remains consistant, With this condition, more aqueous fluid is produced than what leaves the eye. This causes an increase in intraocular pressure.
IOP: higher than 30 mm would indicate glaucoma.
Dilated pupil: it won’t get smaller with light. Normally with light, the pupil will become constricted.

31. Glaucoma Causes Inherited Secondary - obstruction of drainage angle
Neoplasia
Luxation of lens
Hemorrhage
Uveitis (inflammation of ciliary body, iris, choroid)
Inherited: A primary cause, both eyes are involved.
Secondary can be caused by these.
Glaucoma: could also be acute or chronic.

32. Glaucoma
Aqueous humor produced, it then will go though the iris through the eyes drainage system. If the angle is clogged, then it will not go through the drainage system, resulting in increased intraocular pressure.

33. Fluid circulation in the eye:
1 minute

34. Glaucoma Diagnosis IOP >30 mm Hg Schiotz Tonometer Tono-Pen
Schiotz Tonometer: It has numbers with It has a plunger on the bottom that taps the eye and gives us our IOP.
Tono-Pen: Digital reading
Schiotz Tonometer
Tono-Pen

35. Glaucoma Treatment Acute - EMERGENCY
Latanoprost (Xalatan 0.005%)- Facilitates aqueous outflow
Dichlorphenamide (Daranide) - Decreases aqueous production
Surgical
Cryosurgery or laser -destroys part of ciliary body to decrease aqueous production
Chronic
Enucleation to relieve pain
Acute is an emergency because the pressure is usually over 60mm.
Cryosurgery: dog is placed under anesthesia and a probe that’s as cold as -80˚C is used on the sclera (the outside of the eye) to freeze the ciliary body, to kill the cells that produce the aqueous humor. The amount of damage done to the ciliary body has to be sufficient enough to make sure there is a balance between the production of the aqueous humor and its drainage.
Laser: better results with less severe side effects.

37. Ulcerative Keratitis(Corneal Ulcers)
Causes
Trauma
KCS (Keratoconjunctivitis Sicca)
Herpesvirus (cats)
Signs
Pain
Epiphora
Blepharospasm (eyelid spasm)
4 layers: Epithelium, stroma, Descemet membrane, and endothelium.
Corneal ulcer: full-thickness loss of the corneal epithelium that exposes the underlying stroma.
Cats with Herpes virus: the virus invades the corneal epithelium which produces an ulcer.

38. Corneal Ulcers Diagnosis: Fluorescein Dye Test
Numb the eye to do this. The fluorescein stain is absorbed well by the underlying stroma, but not by intact epithelium. If the stain is absorbed, it indicates that it is an ulcer.
They put a black light on the eye.

39. Corneal Ulcers Treatment Topical atropine (1%) ointment
Decrease pain, blepharospasm
antibiotic or antiviral ointments or solutions
Surgery
Eyelid flap, conjunctival flap
Serum (autologous/autogenous)
Blocks proteases released from leukocytes and bacteria
keep in refrigerator (throw out after 72 hours)
Serum is taken from the patients blood sample. Apply 1 drop into eye every 2-4 hours daily. Recheck eye after to see if there is improvement.
Eyelid flap: use the third eyelid to cover eye so it can get better.

40. Corneal ulcer
1 minute 40 seconds
Eyelid flap procedure

41. Deep Corneal Ulcer Descemetocele– erosion to membrane
Treat with a surgery
A descemetocele describes a deep corneal ulcer in which the overlying epithelium and stroma are no longer present so that only descemet's membrane prevents globe rupture.

42. Conjunctival flaps 9 minutes
Conjunctival flap or grafting surgery is performed under general anesthesia. We utilize the latest in surgical equipment and techniques to relocate a portion of the pet’s conjunctival tissue to cover the corneal ulcer. It is stitched in place using specialized dissolvable suture material
Descemet’s membrane is the innermost membrane of the cornea

43. Corneal Ulcers Client info Most ulcers heal quickly with treatment
Avoid using old medications
No ointment w/cortisone! will inhibit healing of ulcer
Do not touch eye with ointment applicator

45. Chronic Superficial Keratitis (Pannus)
Definition: Pannus - superficial corneal vascularization/scar tissue
Progressive, bilateral, can result in blindness
Cause
Thought to be immune-mediated
(Infiltration of cornea with lymphocytes, plasma cells)
ultraviolet light/high altitudes increases incidence
Signs
Opaque lesions that begin at limbus and extend into cornea
Milky, pink, or tan
Vascularization: abnormal or excessive formation of blood vessels (as in the retina or on the cornea)
It an inflammatory condition of the cornea in dogs, particularly seen in the German Shepherd. Both eyes are usually affected. The corneas gradually become pigmented and infiltrated by blood vessels, and the dog may eventually become blind
Lesions usually start at the limbus: the junction of the cornea and sclera in the eye
Progressively enlarges and usually involves the entire cornea

46. Chronic Superficial Keratitis (Pannus)

47. Chronic Superficial Keratitis (Pannus)
Diagnosis
Rule out KCS, corneal ulcers
Treatment
Corticosteroids often lifelong
Cyclosporine often lifelong
Antibiotic eye ointment
Client info
No cure
If Rx is stopped, disease will return and progress
High altitudes and ↑sun predispose animals
Rule out Corneal ulcers due to steroid therapy
Cyclosporine: treats chronic dry eye

48. DOGGLES!!!!

49. Keratoconjunctivitis Sicca (KCS)
Definition: Lack of tear production
tears lubricate, nourish, ↓bacteria, aid in healing
Tears from 2 glands: 70%:Lacrimal gland; 30%:Nictitans gland
Signs of KCS
Recurrent conjunctivitis, corneal ulcers, keratitis
Dull, dry, irregular cornea, conjunctiva
mucoid ocular discharge
Blepharospasm
Crusty nares
Occurs when tears aren't able to provide adequate moisture
Loss of both glands results in KCS
Most cases are idiopathic. Usually seen in older animals. More common in neutered animals due to the loss of sex hormones.

50. KCS

51. KCS Treatment Tear stimulation Artificial tears Client info
Drugs: cyclosporine, pilocarpine
Artificial tears
Client info
Prognosis is guarded for resolution
Failure to treat → blindness
Parotid duct (salivary gland) transposition: The parotid duct is a tube that carries saliva from the parotid salivary gland into the mouth. In a parotid duct transposition, this duct is surgically relocated from the mouth into the pocket below the eye – this results in the eye being kept moist with saliva instead of the missing tears.
Can be done if treatment does not work.

52. Cataracts
Definition: Opacity of lens that causes reduced vision; most common disease of lens
NOT NUCLEAR/LENTICULAR SCLEROSIS!!
Cause
Genetic
Secondary:
Diabetes mellitus (bilateral; within 1 y of disease; ↑glucose → ↑fluid in lens)
Trauma Lens luxation
Seen in dogs but also seen occasionally in cats
Aging cells within the lens become dehydrated and overlap each other, producing change in the reflection of light: lens looks gray and opaque (unable to see through)
Lenticular sclerosis: normal change in aging animals
Lens luxation: the support ligaments of the lens weaken or break causing the lens to dislocate from its normal position

53. Cataracts Signs Diagnosis Progressive loss of vision
Opaque pupillary opening
Diagnosis
Must be distinguished from senile nuclear sclerosis
Normal old age change; graying of lens; bilateral; usually does not affect sight
Do a full ophthalmologic exam

55. Cataracts Treatment Client info Surgical removal of lens
Treat underlying cause
Client info
Most cataracts are inherited, so don’t breed affected dogs
Dogs can live quality lives even with bilateral cataracts

56. Progressive Retinal Atrophy
A group of hereditary disorders causing loss of rods, cones, and/or blood supply to the retina
Signs - slow onset of blindness
Loss of night vision (rods) → loss of day vision (cones) Dx
Ophthalmic exam
gray, granular appearance of retina
Hyperreflective retina
Narrow blood vessels, optic nerve atrophy
Retina: a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.
Rods: Black and white vision
Cones: color vision
Retina needs to be functioning correctly in order for vision to occur.
Hyperreflective retina: spots on retina

57. Can get at any age

58. PROGRESSIVE RETINAL ATROPHY
Attenuation: less intense, you can see its much lighter
optic nerve atropy and vessel
attenuation
Normal canine retina

59. Progressive Retinal Atrophy
No Treatment
Client info
This is an inherited disease
Avoid buying affected dogs
Have ocular exam by board certified ophthalmologist
Blind animals adapt well, but may have trouble in strange surroundings
Cats need well balanced diet
Taurine deficiency can lead to PRA
Not as common in cats

60. Detached retina Usually related to trauma
Retina will look “folded” down from back of the eye
Animal will appear blind (no PLR) in affected eye
No treatment
There will be no pupillary lens reflex (normal constricts when light hits it)

61. Proptosed Globe Cause Clinical Signs Trauma
Retrobulbar abscess or neoplasia
Clinical Signs
Protrusion of the globe,
Eyelids unable to close, may be trapped behind globe
Eye is literally popped out
Retrobulbar abscess occurs when an infection or intrusion causes a pus filled cavity to form behind the eyeball

62. Proptosed Globe

63. Proptosed Globe – Treatment
Lubricate immediately
Reduce the globe into the socket ASAP to reduce trauma to optic nerve, if the eye is viable
Enucleation if optic nerve severed
Systemic and topical antibiotics

64. Proptosed Globe

65. Prognosis Favorable prognosis Unfavorable prognosis non-brachycephalic
brachycephalic dog
Normal PLRs
normal findings on ophthalmic exam
proptosed eye with vision on initial presentation
Unfavorable prognosis
non-brachycephalic
cat
blood in the anterior chamber
no visible pupil
facial fractures
optic nerve damage and/or torn extraocular muscles
The extraocular muscles are the six muscles that control movement of the eye and one muscle that controls eyelid elevation