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.