What is the tear film, and why is it important?
A. The tear film is the liquid coating of the cornea or clear anatomical structure of the eye. As the cornea is an avascular structure with no direct blood supply, it requires the tear film for lubrication and nutrition which are crucial to eye health. If there is an abnormal tear film or a decrease in its three components, ocular surface disease occurs.
B. The tear film is composed of three integrated layers that work closely together. A disruption in one or more of these layers, greatly affects the quality of the others.
1. Lipid layer – thin oily outer layer secreted by the Meibomian glands at the margin of the eyelids. This layer prevents evaporation of the middle aqueous layer.
2. Aqueous layer – thicker middle layer secreted by the orbital and third eyelid
lacrimal (tear) glands. This layer provides the necessary nutrients and oxygen needed for a health cornea.
3. Mucin (mucous) layer – thin inner layer secreted by the goblet cells of the conjunctival tissues. This layer provides a smooth ocular surface (for improved vision) and attracts the aqueous layer to the eye surface.
2. What are some clinical signs of tear film disease/dysfunction in dogs and cats:
1. Squinting (increased blinking frequency or holding the eye closed) 2. Rubbing of the eye or face
3. Epiphora (tearing)
4. Thickened and sometimes colored ocular discharge
5. Red eye (irritation and redness of the conjunctival tissues)
6. Corneal scarring (fibrosis or pigmentation)
7. Corneal erosion or ulceration (a wound of the corneal surface)
8. Decreased vision
3. What are some clinical conditions or eye diseases that can adversely affect the tear film?
A. Eyelid inflammation – allergies, self-trauma (rubbing), infections, tumors.
B. Eyelid surgery – cryotherapy, mass/tumor removal.
C. Corneal inflammation – dry eye, breed-related exposure, immune mediated
D. Corneal surgery – corneal grafting surgeries.
E. Cataract surgery
F. Conjunctival inflammation – infections (feline – herpesvirus, mycoplasma,
chlamydia), Pannus, dry eye.
G. Conjunctival surgery – mass removals, biopsies, conjunctival grafting.
4. How can Vizoovet help my pet?
If your pet has been diagnosed and suffers from an abnormal tear film, Vizoovet may be able to help! This product normalizes the bodies natural tear film improving the overall health of the ocular surface and may minimize the clinical symptoms of disease. Please consult your veterinarian or veterinary ophthalmologist and ask if Vizoovet is a good choice for your pet.
Vizoovet IS Safe For All Species
Tear staining is a sign of KCS
DRY EYE (KERATOCONJUNCTIVITIS SICCA)
DJ HAEUSSLER, JR., BS, MS, DVM, DACVO
CHRISTINA KORB, DVM
WHAT IS KCS?
Keratoconjunctivitis sicca (KCS), or dry eye, is an ocular condition commonly diagnosed in dogs. It is less common in other species. Keratoconjunctivitis sicca results most often from an inadequate quantity of tears or a deficient quality of tears. Tears are produced by the lacrimal, or tear gland, and the gland of the third eyelid. Tears are needed to provide lubrication and nutrition to the cornea, as well as remove debris and/or infectious agents from the eye.
WHAT CAUSES KCS?
The most common cause of KCS in the dog is immune mediated inflammation of the tear glands. Other causes of KCS include but are not limited to:
Congenital disease, such as small or absent lacrimal glands
Infectious disease, such as canine distemper virus
Neurologic deficiency, such as loss of nerve innervation to the eye
Endocrine disease, including hypothyroidism, Cushing’s disease, and diabetes mellitus
Prolapsed gland of the third eyelid (“cherry eye”) and/or removal of the gland of the third eyelid
Radiation therapy near the eye
Drug toxicity, including use of sulfa derivative medications