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  • Microcysts?

    Dear Dr. Holly,

    Your post on RCE's and eye drops with oncotic pressure is so helpful. Thank you for that information.

    I have a question about "microcystic edema." You say that it is like the tissue become waterlogged, and I was wondering if you could explain more about it.

    Are there cysts that break free and come to the surface or is this a condition that is in the epithelium or in the basement membrane?

    Thanks so much,

  • #2
    Microcystic edema

    I apologize Liz for not explaining things immediately and thank you for asking me to clarify.

    Microcystic edema is a type of edema of the cornea epithelium. Water collects among the cells (intercellularly). Also we think it may collect between the basal epithelial cells and the basement membrane interfering with adhesion. Basal cells form the bottom layer of the corneal epithelium.

    The term cyst just means in this case small droplets of water within a tissue and between cells. It is not a cyst in the most common meaning of the word (hence the "micro" modifier).

    Dr. Holly
    Last edited by Frank Holly PhD; 01-Feb-2008, 10:10. Reason: typo, also to clarify meaning
    [SIZE="3"]Dr. Holly[/SIZE]


    • #3
      Thanks for your response, Dr. Holly.

      That makes sense. So, there is really another layer in between the epithelium and the basement membrane, that of basal cells, and it is there in the irregularity of those cells that the attachment problem happens?

      I had mistakenly thought that it was the basement membrane itself that contained the problematical cells.

      Thanks, again, and please know that I eagerly read your posts!



      • #4
        Basal cells and basement membrane

        Hello, Liz: The epithelium on the cornea is five cell layers thick. The bottom layer is made of columnar cells and those sit (stand?) on the basement membrane. The basement membrane is extremely thin as compared to a cell. Both the bottom of the epithelial tissue facing the basement membrane and the surface of the basement membrane are hydrophobic according to measurements I made in rabbit eyes several decades ago.

        For this reason, a continuous water layer normally cannot form between them as that layer would have a negative disjoining pressure. That term was defined by Derjaguin, a Soviet academician in 1940. It just means that as such a film thins its energy decreases. So the process becomes spontaneous until the film is gone.
        [SIZE="3"]Dr. Holly[/SIZE]