Article Date: 2/1/2001

Periocular Skin
Ophthalmic Management of the Periocular Skin Leads to Better Patient Care
Why you need to know skin anatomy.
By Peter T. Pugliese, M.D., Reading, Pa. and Richard E. Castillo, D.O., O.D., Tulsa, Okla

The eyes are the most dynamic and complex surface structures of the body. We often forget that they consist of three components: the globes, the bony orbits and the periocular skin and its appendages (see illustration). Comprehensive eye care involves addressing the needs of all three components, of course, but here we'll focus on care of the periocular skin, which significantly contributes to the health and function of the eye and influences a patient's ability to see.

Never trivialize the importance of this skin to eye health; not only is it different from any other skin, but its influence is far greater than you perhaps realize. Here's what you and your patients need to know.

WHAT IT DOES AND WHY IT'S IMPORTANT

The eye is themost complex surface structure of the body.  There are three major parts: the globe, the bony orbit and the periocular skin.  comprehensive eye care should embrace all three components.

Aside from protecting the globe from the external environment, the periocular skin also acts as a barrier against evaporative tear loss. Eyelids are part of the lacrimal system, which distributes, drains and replenishes the precorneal tear film layer that's vital to both the physiology and optical properties of the cornea.

The delicate lid margins contain glandular elements vital to tear film composition. And finally, the bulbar face of the eyelids comprises the palpebral conjunctivas, which play a pivotal role in tear film physiology and in guarding against eye disease.

Never underestimate the importance of this relationship between the periocular skin and the eye. The eyelids are in direct contact with the eye some 15,000 times per day! Eyelid problems are involved in most infectious and inflammatory conditions of the adnexa and ocular surface, such as meibomian gland dysfunction, blepharitis, blepharoconjunctivitis, dry eye syndrome, peripheral corneal derangements and rosacea. It's therefore critical that you ensure that periocular skin is not only clean, but also healthy.

To best know how to do this, you need to understand the anatomy and physiology of normal skin. Along the way, you'll discover how periocular skin differs from other skin and why it should be an integral part of eye care. (See table below for more detail.)

ANATOMY OF THE SKIN

The skin is the largest organ of the body. It weighs slightly more than 3 kg (6.6 pounds) and covers nearly 2 square meters of area. It measures between 1.5-mm and
4-mm thick on average. It's thickest on the back and soles of the feet (4 mm). The scalp, forehead and wrist skin all measure less than 2 mm. The thinnest and most complex skin is the periocular skin (about .075 mm, or 75 µ).

Skin is dynamic; it constantly renews itself. It's also mosaic, meaning that the cells don't always grow at the same rate. Its primary functions are protection, sensory perception and as a guard against the passage of water, chemicals and microbes.

The skin has two surfaces -- an external surface (the epidermis) and an internal surface (the dermis).

 

COMPARISON OF SKIN TYPES

 

PERIOCULAR SKIN

TYPICAL SKIN

Thickness of dermis + epidermis 

Thinnest of the body; less than 2 mm

 2 mm to 4 mm

Thickness of epidermis

 Thinnest of body; 75� (.075 mm)

 150-500� (0.15 to 0.5 mm)

Thickness of Stratum Corneum

 Thinnest of body; 10 or fewer layers 

10 to 50 layers

Permeability of skin 

Ten times less lipid content 

Ten times more lipid content

Epidermal kinetics 

Most rapid of the body; 5 to 7 days 

15 to 45 days

Presence of rete-ridges

 Largely absent

 Junction dermis-epidermis

Papillary dermis and Reticular dermis

 No perceptible division 

Clear distinction

Location of dermis 

In between epidermis and orbicularis muscle 

Between epidermis and fat layer

Location of muscle

 Closest to the surface 

Below fat layer

State of movement 

In constant motion 

Not in constant motion

Number of appendages Per sq mm 

Highest of the body 

Significantly less than periocular skin

THE EPIDERMIS

The epidermis is the keratinized outer skin layer. This tiny layer is our eyes' only real protection against the whole environmental world. (See figure)

Though it's thinner than the paper of this page, the epidermis is composed of four layers of cells. These include:

Skin structure. Note the critical layers and the important appendages such as the sebaceous glands, hair follicles and sweat ducts. In periocular skin, this entire area is less than 2-mm thick.

Peter Elias, M.D., has shown that the intercellular space in the stratum corneum is the key to barrier function. He pictures the stratum corneum as bricks (the corneocytes) and mortar (the lipid-containing intercellular spaces).

Lamellar bodies fuse together with the plasma membrane and secrete their contents into the intercellular space. The intercellular space then expands until it comprises 10% to 40% of the total volume of the stratum corneum.

Dr. Elias also noted that the ability of the skin to resist permeation isn't related to the thickness of the skin, but rather to the amount of lipids present in it.

It's important to realize that "permeation" doesn't refer to water, but to pathogens and organic and industrial oil-soluble pollutants. The eyelids are ten times more permeable than other body areas. It's not only that they're thinner, but that the lipid content is much lower than in other body areas. Ophthalmic management of the periocular skin is therefore critical.

THE EPIDERMAL APPENDAGES

You need to know about three types of appendages. They are the hair follicles, the sebaceous glands and the sweat glands.

The keratinocyte originates in the basal layer and is plump with moisture from the bloodstream. As it moves upward it flattens, loses moisture and helps to form the skin barrier. Finally, hardened and dried, it helps the body dispose of toxins as part of the stratum corneum.

These sweat glands help regulate body temperature and create perspiration. The heat that's required to change water from a liquid to a gas or vapor is taken from the body and used up in conversion. As a result, the body cools down as the sweat evaporates from the skin.
Sweat is composed mainly of water (99%) and minute amounts of dissolved substances including sodium chloride, urea, sulfates and phosphates. Sweat glands tend to become plugged. Every time a gland furnishes an opportunity to form an accumulation of secretion, it creates a ready, warm and moist environment for pathogens to fester.

The barrier function of the stratum corneum. The skin's ability to resist permeation is related to the amount of lipids it contains, not to its thickness. 

THE DERMIS

The dermis is a tough but resilient structure that allows the skin to move, absorb shocks, and cool and warm the body. It also permits the passage of nutrients to the epidermis.

The dermis is composed of loose connective tissue bound with ground substance. Within it are nerves, lymphatics, blood vessels and the organs of the glands and hairs. The dermis of the periocular skin is less than 2-mm thick.

Ordinarily, the dermis lies between the epidermis and the subcutaneous fat layer, but in the eyelid, it lies between the epidermis and the orbicularis muscle. In fact, the eyelid is the place in the body site where striated muscle most closely approaches the skin surface. Without the cushion of subcutaneous fat, the periocular skin is more easily traumatized.

HOW THE SKIN MAINTAINS ITSELF

After accommodating the critical appendages, the skin's other main function is to provide a protective barrier. Therefore, it's supple, yet strong and elastic. Also, it has the ability to repair itself when damaged by soap, sunlight or other environmental agents.

As we've seen, it takes about 30 days for skin to grow from the basal layer to the stratum corneum, except for periocular skin, where the growth period is much shorter.

The stratum corneum is constantly being lost to the environment, at the rate of about one layer per day. The rate of skin renewal depends on factors like the thickness of the skin, its location (the further from the heart, the slower it grows) and the person's age. There's even a growth variation between day and night.

The skin is most active at night. Therefore, patients should always clean the skin and apply treatment products twice a day, but especially at night.

OPTIMUM SKIN

Skin as unique, fragile and sensitive as periocular skin needs to be kept clean and healthy. Here are some guidelines to follow.

The periocular skin appendages include critical glands (Zeis, Moll, Krause and meibomian) that directly influence vision and vision comfort.

An effective skin care product must do the following:

WIDE RANGE OF BENEFITS

As you can see, your patients' health will benefit substantially from proper care of the periocular skin. Furthermore, skin that's well cared for has better density and elasticity. Patients will look younger as well as more vibrant.

Most patients not only like to see better, but look better. It's well documented that when we feel better, our body's composition and chemistry are different, healthier. So periocular skin care can potentially improve your patients' health on a very wide front! 

Peter T. Pugliese, M.D., has an international reputation as one of the world's most respected authorities in skin care research. Dr. Pugliese has more than 100 publications to his credit, has been the recipient of numerous prestigious awards and has speaking engagements from Paris to Tokyo. Dr. Pugliese holds seven patents. Many of his discoveries have influenced the decisions of leading cosmetic and pharmaceutical companies world wide.

Richard E. Castillo, D.O., O.D., is an associate clinical professor of ophthalmology at Northeastern State University College of Optometry, Okla. As medical director of a private eye and laser center in Tulsa, Dr. Castillo has more than 12 years of practical experience in the medical management of eye disease and oculoplastics , as well as anterior segment surgery, refractive procedures and laser surgery. Dr. Castillo has been a sought-after speaker at various continuing education programs nationwi


Optometric Management, Issue: February 2001