Saponification

If we consider the multiple interactions between the microbiome of our eyes and the ocular surface, we will recognize that our ocular flora, specifically bacteria, secrete a multitude of enzymes that liberate nutrients from the environment. Staphylococcus species are common flora and are well known for their ability to secrete lipases.¹ These enzymes break down lipids, allowing digestion and absorption of nutrients, essentially feeding the bacteria and enabling them to grow and prosper.

Clinically, we can see the effects of lipases on the lipids of the ocular surface. This enzymatic reaction, called saponification, appears as foamy soap bubbles (Figure) when bacterial overload and activity reaches a dysfunctional level. The true definition of saponification is the act, process, or result of making soap. This finding has been described for some time by clinicians and has been associated with blepharitis, specifically posterior blepharitis, and is better defined as meibomian gland dysfunction (MGD).² MGD is the most common form of dry eye. Symptoms can include burning, stinging, watering, blurred vision, and a dry or gritty sensation.

In the movie Fight Club, the Paper Street Soap Company uses rendered fat and lye to make soap. Soap is an excellent cleaner because of its ability to act as an emulsifying agent. We can appreciate how dissolving and mixing oils is detrimental to ocular surface health. Bacteria are achieving a similar breakdown of lipids (using lipases instead of lye) on the ocular surface.

HOW CAN WE TREAT OR DOWNREGULATE LIPASES?

Lid hygiene is a major factor in helping to regulate the microbiome. I do not recommend baby shampoo, as I find it too irritating to the ocular tissues. It’s also counterproductive to add more soap to an already soapy environment.

Epstein et al published a poster that demonstrated the effectiveness of hypochlorous acid (Avenova, AvenovaEyecare) for the inactivation of bacterial lipase.² They noted complete inactivation of lipase, while several other common lid products appeared to have minimal effect.² Some also postulate that tetracyclines downregulate lipase activity. This enzymatic effect is at the root of their therapeutic benefit in MGD, rosacea, and patients with acne.¹