Lid Contour Changes

[clairvoyant]

Being a patient with mild blepharitis I am now intrigued by disease, most importantly this one. With all your knowledge in tear film physiology I was hoping you would have some insight into this aspect of the disease. And if so would be willing to share.

It is my understanding that blepharitis causes lid countour changes making the eye area (orbital area?) a more round shape.

That lead me to a series of questions for which I do not have anwsers. Firstly, I wondered if this lid contour change is perminent? Or is there something that can restore an anatomically correct eye area. Like fully controlling the inflammation? Be it diet, exercise or some type of anti-inflammatory. Or might it take more? Like altering genes?

I don't know too much about the genes and their effect on the disease but I did read an article about it. I think it stated that with blepharitis certain genes do not fill out roles they once did.

Hope to hear back from you.

[Frank Holly PhD]

Interesting query! Mike Lemp and I in one of our early papers claimed that several blinking abnormalities can cause problems with the tear film, with the ocular surface, with the tarsal inner surface, and so on. What you mention is the lack of lid-globe congruity. The evenness of the gap between the two solid surfaces having a relative and considerable speed difference between them definitely affects the shear rate distribution. When the lid itself is rigid then the system becomes less forgiving for such abnormalities.

If the gap is somewhat larger at locations(< 150 micrometers) that is less of a problem unless air starts to enter under the lid. Where the gap becomes real narrow (< 1 micrometer) that could mean a switch over to boundary lubrication, greater stress transfer, and marring of the tissue surfaces. One could envision sterile inflammation of the lid secondary to increased friction.

In general, the lacrimal system is quite forgiving, if one considers the success of contact lens wear. Especially initially, the lens design did not take into account the interference of a foreign body, actually a prosthesis to tear film instability and problems with lubrication and the lenses still worked fairly well.

Lasik surgery does alter the corneal profile considerably, so it should affect the lid-globe congruity. While over most area the gap becomes larger, in the peripheral region there could by some tight gaps. If so, that could explain in part the increase in lid inflammation and meibomian gland problems.

If this were the case then the role of an artificial tear that has a high disjoining pressure under the lid would resist tear layer thinning. In such eyes the wettability would be doubly as important.

Sorry I cannot address the possible existence of defective genes. 'With tongue in cheek,' is this not often a fancy way of blaming the patient for a possible iatrogenic problem?