QUESTIONS

1. Around the eyelashes there are sebaceous glands and sweat glands. Which are the Glands of Zeis & which are the Glands of Moll?
    
2. What do Meibomian glands do?
    
3. Which gland produces more tears? The one in the orbit or the one in the third eyelid?
    
4. What is a Harderian Gland?
    
5. I'm sure you know that tears have 3 layers: water, fat & mucus. But in what order do they occur?
   
6. List all the causes you can think of for KCS.
    
7. What is a Phenol Red Thread test?
    
8. What is a Tear BUT test?
   
   
   
   
    

ANSWERS

1. The Glands of Zeis  are the sebaceous glands and the Glands of Moll are the sweat glands.  The way I remembered this in school was I pictured Zeus (close enough) & a woman named Moll.  As you know, Zeus had a reputation for woman chasing, making him  a "greasy" kind of guy and any woman in his vicinity would most likely be sweating.
   
   
   
   
    
2. Meibomian glands produce Meibum (how do you like that?).  This is basically a fatty material. Meibomian glands are also called "Tarsal glands."
   
   
   
   
    
3. The gland in the orbit produces about 70% of the tear film.  The gland of the 3rd lid produces 30%.
   
   
   
   
    
4. Sounds like one of those accessory glands of the male reproductive tract but it isn't. You probably don't know what it is because dogs & cats don't have one. Birds and reptiles do and cattle do.  In rodents, this is the gland that produces porphyrin and is responsible for the red tears we often see in rats.  There are apparently many types of Harderian glands and different types secrete different types of secretions.
   
   
   
   
    
5. Fat is the outer layer, water is in the middle, then mucus.
   
   
   
   
    
6. Causes of KCS:
   
   a) idiopathic :) (presumed immune-mediated since it responds to immune suppression)
   
   b) Iatrogenic (snipped off a cherry eye rather than put it back, gave sulfa drugs, irradiated the eye, general anesthesia can do it)
   
   c) Infection in the tear gland (distemper would be the obvious)
   
   d) Trauma (getting conked on the head at the area of the gland)
   
   e) systemic disease
   
   f) Neuro changes (facial paralysis leading to inability to blink)
   
   g) congenital
   
   
   
   
    
7. A Phenol Red Thread test is soon to be marketed as an alternative to the Schirmer tear test.  Here a tiny thread is held in the lower conjunctival fornix for 15 seconds and wetness is measured. The idea is that the little thread won't stimulate the cornea like a big old piece of filter paper will and you'll get a truer measure of natural wetness.
   
   
   
   
    
8. A Tear BUT (Break up time) test measures the time it takes to get the first dry spot on the cornea after a blink.  You stain the eye with fluorscein, let the animal blink to spread the dye, then hold the animal's lids open until there is a hole in the dye. Normal is 15-25 seconds.