At each new patient encounter, it is important to ask patients their occupation. What type of environment challenges their ocular surface during work hours? What type of products are they using in their daily routine? Are they medical personnel, maintenance professionals, or housekeepers using specialty soaps or disinfectants?

Lessons on pH

One of my childhood recollections is a discussion with my mother, who holds a PhD in organic chemistry, regarding the virtues of a popular facial cleanser in my childhood years. “pHisoHex is pH balanced” she said, “so it is better for your skin.” At the time, the pH comment wasn’t important to me. What was important was that my mother said that I should wash with the product.

As a quick review, pH (potential of hydrogen) is a measurement of the degree of the acidity or alkalinity of a solution as measured on a scale (pH scale) of 0 to 14. The midpoint of 7.0 on the pH scale represents a neutral solution that is neither acid nor alkaline (i.e., water). Numbers below 7.0 indicate acidity and greater than 7.0 indicate alkalinity. Typically, healthy skin has a slightly acidic pH average of 5.5. Although controversial, dermatologists believe that maintaining the skin surface physiological pH prevents overgrowth of microorganisms and protects the skin’s integrity and functions (Mukhopadhyay, 2011).

Many of the contaminants that contact our skin, such as chemicals from the atmosphere and harmful bacteria, are alkaline in nature. The skin’s natural acidity neutralizes chemicals and bacteria, a necessary part of the body’s defense system. The “acid mantle” is a thin, oily protective film made up of sweat and sebum that sits on top of the outermost layer of our skin. It can become unbalanced with the use of strong alkaline soaps, cleansers, and detergents. Excess perspiration may also affect skin pH.

Skin cleansers are surface active substances, primarily detergents and soaps. Soap cleans by acting as an emulsifier. Detergents are primarily surfactants, which can bind to skin keratin and cause protein denaturation, damaging the cell membrane of keratinocytes.

Cleanser residues may also be a potential skin irritant, and the alkaline pH of some soaps may cause damage to the lipid bilayer of the stratum corneum of the skin, causing dryness (Bikowski, 2001).

Checking pH

What are your patients using to clean their skin, particularly around the eyes? How do the products associated with their day-to-day activities affect their lid margins and ocular surface?

This weekend, I carried my handy-dandy pH measuring pencil around with me, testing my skin after contact with various products associated with my weekend routine. Most soaps and body products were slightly acidic; however, there were instances in which my wrist displayed the navy blue color of alkalinity (Figure 1). Keep in mind that many of these alkaline products are/may be aerosolized, creating fumes that can linger on surfaces, including the delicate mucous membranes of the eyes, nose, and throat.

I encourage you to pursue lifestyle questions with your patients, particularly those who have recalcitrant lid or ocular surface disease. You may identify a hidden product-related culprit of eye irritation. Keep in mind the pH pencil! CLS

For references, please visit www.clspectrum.com/references and click on document #271.