Meibomian gland dysfunction (MGD) leading to evaporative dry eye is the leading cause of dry eye or much more common as compared to aqueous deficient dry eye. We have about 30-40 meibomian/oil glands that line the bottom and top lids. These glands largely contribute to the oil layer of the tears, which prevents the water layer from evaporating as fast. Just about every patient I see, the tears evaporate faster than “normal”. Text book normal tear evaporation time is 10 seconds. This is wildly uncommon now. I would say majority of my patients’ tears evaporate anywhere from 2-5 seconds, hence the large increase in dry eye issues. The act of blinking is what primes the oil glands and releases the oils from the glands. The less we blink, the oils become stagnant and eventually with atrophy and die off.
Blepharitis is the overgrowth of normal bacteria that naturally lives on our skin all of the time that over grows on the lids and lashes. It presents itself as flakes at the base of the lashes. Blepharitis causes itchy eye lids, extra crustiness in the mornings, clogging of the meibomian glands with decreased quality of the oils with time, increases inflammation of the lids and tear film, increased dry eye, styes, burning and gritty eyes. The flakes also will begin to get into the tear film and contribute to increased blurred vision and sandy-feeling eyes. Blepharitis is more common in contact lens wear due to decreased blinking, increases with age, and possibly has a hereditary component. I have also seen blepharitis drastically increase across all populations after the past year, likely due to mask wear and breathing back in your own bacteria, especially amongst my younger kid population, which I would say is historically much more rare than my middle aged to older patient population. Blepharitis also becomes a very good food for what we call Demodex, which is in the mite family. This is like having bugs on the lashes, for which the BlephEx treatment is curative.