What makes an item 'contaminated' in the context of sterile technique?

An item is contaminated when it has come into contact with anything non-sterile, including: being held below waist level, having its sterile packaging edges touched, being struck through by moisture, being touched by an ungloved or non-sterile-gloved hand, or being left uncovered and exposed for extended periods. When in doubt, assume an item is contaminated and replace it.

What is the difference between the open and closed gloving methods?

In the open (pluck) method, used when not wearing a sterile gown, the first glove is picked up by its inner cuff and the second is handled by sliding the gloved fingers under the outer cuff of the second glove. In the closed gloving method, used in the OR with a sterile gown, the hands stay inside the gown cuffs throughout gloving so that bare skin never contacts the outside of the gloves, maintaining sterility of the glove exterior.

What is strike-through contamination?

Strike-through contamination occurs when moisture penetrates a sterile drape or wrapper that is resting on a non-sterile surface. Microorganisms travel through wet material by capillary action, rendering the sterile side contaminated. This is why sterile fields must remain dry, and why surgical drapes must be replaced if they become wet.

Why are the edges of sterile packaging not considered sterile?

The outer 1-inch border of sterile packaging wrappers is considered non-sterile because it is handled by ungloved hands during opening. Only the interior contents and the central portion of the inner wrapper are considered sterile. When presenting sterile items, the packaging is folded back by non-sterile personnel to expose the sterile contents without touching them.

Is hand hygiene sufficient before assisting with an intravitreal injection?

For non-scrub roles in assisting with intravitreal injections (such as opening supply packaging or preparing drops), hand hygiene plus clean gloves may be sufficient depending on the facility protocol. However, if you are handling sterile instruments or directly assisting in a scrub role, a surgical hand scrub and sterile gloves are required. Always follow your facility's specific protocol and the physician's direction.

Sterile Technique for the CPO Exam

Sterile technique is the foundation of surgical safety. Any invasive ophthalmic procedure, from cataract surgery to intravitreal injections, requires strict adherence to aseptic principles to prevent devastating infections. Understanding these principles is both a CPO exam requirement and a non-negotiable clinical skill.

What Is Sterile Technique?

Sterile technique (also called aseptic technique) refers to practices that eliminate or prevent contamination by microorganisms. A sterile item contains no living microorganisms, including spores. This is different from simply being "clean," which means free of visible dirt but not necessarily free of pathogens.

Think of sterile technique as maintaining an invisible barrier. Every time that barrier is crossed, the risk of infection increases. Your job in the surgical or procedure room is to protect that barrier at all times.

Establishing and Maintaining the Sterile Field

A sterile field is a defined area where all items are sterile and only sterile personnel or items may enter. Typically, this includes a draped Mayo stand or instrument table covered with a sterile drape, and the sterile-gowned and gloved surgeon.

Key rules for the sterile field:

Only sterile items touch sterile items. Never reach over or across a sterile field with an ungloved hand.
The sterile field is above waist level. Items held below the waist are considered contaminated.
Moisture breaks sterility. A wet sterile drape that contacts a non-sterile surface becomes contaminated through strike-through.
The edges of sterile packaging are not sterile. When opening sterile supplies, the contents are sterile but the outer 1-inch border of the packaging wrapper is considered non-sterile.
Sterile supplies must be passed correctly. Unsterile personnel open packaging and flip or drop sterile contents onto the sterile field without touching the field.

Reaching over the sterile field to hand something to the surgeon contaminate it. Always pass items by opening the sterile package and presenting it so the sterile-gloved person can retrieve it themselves, or drop it onto the sterile field from the wrapper.

Gowning and Gloving

Surgical gowns are sterile and cover the front of the body from chest to knee and the arms from cuffs to elbow. Only the front of the gown from chest to waist and the sleeves are considered sterile; the back of the gown and below the waist are not.

Sterile gloves must be donned using technique that prevents contamination:

Open (pluck) method: Used when not wearing a sterile gown. The outside of the glove is handled only with the cuffed portion using the other gloved hand.
Closed gloving method: Preferred in the OR. The hands remain inside the gown cuffs while gloves are pulled on, so the hands never touch the outside of the gloves.

Once gloved, keep hands above waist level and clasped in front of you when not actively performing a task.

Sterile Scrub vs. Hand Hygiene

Before donning sterile gloves, team members performing scrub roles complete a surgical scrub: a timed, thorough scrub of hands and forearms with an antimicrobial soap or brush, or a brushless alcohol-based surgical hand rub. The goal is to reduce the microbial count on the skin to the lowest possible level.

Standard hand hygiene (soap and water or alcohol gel) is appropriate for non-scrub procedures and when entering and exiting patient rooms, but it does not achieve the level of reduction required for invasive procedures.

The surgical scrub reduces but does not eliminate microorganisms on the skin. Sterile gloves provide the actual barrier. Both are required for scrub roles.

Sterile vs. Clean Technique

Not every procedure requires full sterile technique. The distinction matters for the exam:

Feature	Sterile Technique	Clean Technique
Goal	Eliminate all microorganisms	Minimize microorganism exposure
Gloves	Sterile gloves required	Non-sterile (exam) gloves acceptable
Examples	Cataract surgery, intravitreal injections	Wound dressing changes, instilling drops
Environment	Sterile drapes, sterile instruments	Clean but not necessarily sterile supplies

Key Takeaways

Sterile technique eliminates all microorganisms; clean technique minimizes but does not eliminate them.
The sterile field includes any surface or item that has been sterilized; only sterile items and sterile-gowned/gloved personnel may contact it.
Items below waist level, edges of sterile packaging, and wet sterile drapes touching non-sterile surfaces are all considered contaminated.
Surgical scrub precedes gowning and gloving; closed gloving is the preferred method in the OR.
When in doubt, treat an item as contaminated rather than risk introducing infection.