Look for a 'Sign' When
Inserting Soft Lenses
BY MICHAEL A. GLUECK, M.D., & EVAN THOMAS, O.D.
For the 20 million or so people who wear soft contact lenses, a daily problem is inserting them without turning them inside-out. Placing a reversed lens on the eye decreases visual acuity and can be painful. Sometimes patients don't realize this error until minutes later after some dehydration has occurred at the edge of the lens, which can make immediate correction extremely awkward.
WHAT IS PPHS?
The peripheral perimeter halo sign (PPHS) refers to a curvilinear line of white or colored light around the edge of a soft contact lens. It is visible only when the lens is positioned correctly prior to insertion.
The purpose of our small study was to determine if patients could learn the PPHS quickly and easily and then use it to consistently identify the proper orientation of a soft lens prior to insertion.
TEACHING THE SIGN
We randomly selected 12 current soft contact lens wearers and gave them six different types of soft lenses to test, including bifocals and colored lenses.
After teaching them how to identify the PPHS, we asked our subjects to indicate which side of each lens was to be placed onto the eye. Most study participants correctly differentiated which side of the lens should be placed on the eye.
Our results showed that virtually all patients could learn and use the PPHS easily and readily.
We also tested subjects who don't wear contact lenses and they also understood and learned this method easily. We felt this indicated that the PPHS is easy to learn and use.
A PRACTICAL METHOD
The peripheral perimeter halo sign refers to a bright curvilinear rim of white or colored light on the peripheral edge of the soft contact lens when the lens is directed toward the eye in the correct position prior to inserting. The sign is usually accentuated by placing a drop or two of saline or other appropriate solution onto the concave area of the lens (Fig. 1). When the lens is held incorrectly (reversed), this halo sign is diminished or absent (Fig. 2).
ALL SOFT LENSES SHOW PPHS
With the newest extra thin lenses, the PPHS may not be as evident, but usually this can be overcome by comparing both sides or by not covering the lens with saline. Also, with very thin lenses, the sign may be more evident if the lens is folded slightly between the thumb and index finger. Tinted lenses also demonstrate this sign; the rim halo is the color of the tint.
We believe that the PPHS rim of white or colored light is caused by internal reflection of light within the lens that is directed back toward the observer's retina when the lens is placed correctly. When the lens is reversed, the light is not directed toward the retina and the halo diminishes or disappears.
LENS HANDLING CONFIDENCE
For best visibility of the PPHS, cover thicker lenses with saline, but observe thin lenses when they are dry. We've determined that color actually enhances the sign, particularly in thin lenses.
By showing patients how to use the PPHS, you will enhance their lens handling proficiency and help them avoid the discomfort of an inside-out soft contact lens. CLS
Dr. Glueck is a diagnostic radiologist. He is a patient of Dr. Thomas who practices in Newport Beach, Calif.