1.1 The Wet Eye

Question 1

What is epiphora?

Answer 1

excessive watering of the eye

• this may be due to increased tear production or reduced tear drainage through the puncta

Question 2

What is the composition of tears?

Answer 2

lipid: reduces evaporation of tears

• produced by meibomian (AKA tarsal) glands (1 duct)

aqueous: nourishes the ocular surface

• produced by lacrimal and accessory glands (multiple ducts)
• this component makes up most of the tear volume

mucin: helps the aqueous part adhere to corneal surface

• produced by the goblet cells

Question 3

List the causes of reduced tear drainage.

Answer 3

1. congenital anomalies of the NLS
2. acquired blockage of the NLS
3. eyelid abnormalities (e.g., entropion)

Question 4

How do tears flow?

Answer 4

1. tears drain from the eye into the lacrimal punta (2 per eye: upper and lower)
2. enter the canaliculi and meet together at the lacrimal sac
3. enter the nasolacrimal duct which leaves the orbit and runs within the maxillary bone to open at the nasal punctum (in some breeds e.g. brachycephalic, may open into back of mouth)

Question 5

How do you test the nasolacrimal system?

Answer 5

Jones test (using fluorescein stain)

Question 6

What are the congential anomalies of the NLS?

Answer 6

lacrimal puncta atresia

• absent / covered puncta
• correct by surgical resection of the conjunctiva covering the puncta

micropuncta

• puncta are present but very small
• also common in dogs
• correct by enlargement of the puncta

Question 7

List the major eyelid anomalies.

Answer 7

• symblepharon
• euryblepharon
• entropion
• eyelid coloboma
• ectropion
• diamond eye

Question 8

What is euryblepharon?

Answer 8

a congenital eyelid anomaly characterized by horizontal enlargement of the palpebral fissure

• AKA macroblepharon
• not normal to see sclera in dogs, should just see cornea, indicates large palpebral fissure

“palpebral” refers to the eyelids

Question 9

What is entropion?

Answer 9

an abnormality of the eyelids in which the eyelid rolls inward
- causes irritation and creates abnormal path for tears to drain onto face

causes epiphora BOTH by increased tear production and decreased drainage

Question 10

What is eyelid coloboma?

Answer 10

no eyelid / defective eyelid present
- AKA agenesis

Question 11

What is ectropion?

Answer 11

an abnormality of the eyelids in which the lower eyelid rolls outward or is everted

Question 12

What is diamond eye?

Answer 12

entropion, ectropion, and macroblepharon (euryblepharon) in the same eye

Question 13

What is the palpebral fissure?

Answer 13

the space between the upper and lower eyelids (the opening of the eye)

Question 14

What is dacryocystitis?

Answer 14

blockage of the NLS by foreign body or unidentified debris

Question 15

What is Bonny disease?

Answer 15

orbital and nasal neoplasia

potentially blocking the NLS (but nothing on google about Bonny disease)

Question 16

What can cause increased tear production?

Answer 16

trigeminal nerve irritation (e.g., distichiasis, trichiasis, ectopic cilium, ulcer)

trigeminal nerve innervates the cornea and conjunctiva

Question 17

What is distichiasis?

Answer 17

abnormal growth of lashes from the orifices of the meibomian glands

Question 18

What is trichiasis?

Answer 18

hairs originating from normal position but are contacting the cornea

Question 19

What are eptopic cilia?

Answer 19

eyelash arising from palpebral conjunctiva, usually causing corneal ulceration

palpebral is a term that refers to the eyel

“cilium” is the term for eyelash

Question 20

What are the types of entropion?

Answer 20

under 12wks (congential)

• puppies too young for surgery so temporary tacking sutures are used
• no open wound, simple procedure, less irritating than staples BUT unlikely to have permanent effect

acquired entropion

• due to: eyelid and skull extreme conformations / increased tissue laxity (age and breed related) / loss of orbital fat (weight loss)
• > 10 different techniques depending on the type of entropion

blepharospasm

• eye is closed tightly due to pain, can lead to secondary entropion (aka spastic entropion)

Question 21

How do you differentiate true entropion from blepharospasm?

Answer 21

apply one drop of proxymetacaine (topical anesthetic)

• If entropion persists then it’s a true entropion and needs surgical correction
• If entropion disappears investigate the source of ocular pain

Question 22

What is the Hotz-Celsus procedure

Answer 22

corrects lower eyelid entropion; very versatile technique
- incise parallel to lid margin extending medial and lateral to entropion eyelid area
- second incision to remove skin and some muscle
- close with single interrupted sutures
- initially may look like ectropion post-surgery but this is normal and should resolve

Question 23

What is pannus?

Answer 23

another word for chronic superficial keratitis (CSK)

• non-painful immune-mediated condition that affects the cornea
• elevated pink mass at limbus of eye: infiltration of the cornea with lymphocytes and plasma cells (lymphoplasmacytic infiltrate - LPI) which causes an inflammatory respose
• occurs primarily in middle-aged german shepherds and may be triggered by UV light (dog should wear sunglasses)

Note: if on the third eyelid (nictitating membrane) it is a “plasmoma”

Question 24

How are eyelid masses removed?

Answer 24

• if less than 1/3 of eyelid: wedge resection
• if more than 1/3: referral

Question 25

How do you treat CSK, “pannus”

Answer 25

• long-term topical steroids
• sunglasses (doggles)

if left untreated the entire eye can become pigmented