discovering dry eye
Finding a Place for Punctal Occlusion
BY KELLY K. NICHOLS, OD, MPH, PHD
With projections that more than 14 million Americans have some degree of dry eye, it's important to have different management and treatment options (such as punctal occlusion) available.
Recent products include the Medennium SmartPlug and the Lacrimedics Herrick "blue" plug -- both of which are intracanalicular (in contrast to the Freeman tapered-shaft variety which have a visible cap over the puncta.
The Medennium SmartPlug is made of a thermal-sensitive hydrophobic acrylic, which is activated when it warms to body temperature in the canaliculus. At room temperature, the plug is rod shaped (9mm by 0.4mm) (Figure 1). With heat activation, the plug shrinks and fattens to its final size of 2mm by 1mm within the cannula (Figure 2).
|Figure 1. SmartPlug before insertion.||Figure 2. SmartPlug after insertion.|
The process of shape change takes about 15 to 30 seconds, and nine times out of 10 requires no additional placement beyond the initial insertion of approximately one fourth to one half of the rod into the canaliculus.
In theory, the plug shape matches the internal canaliculus size, which should therefore minimize plug loss. Medennium's FDA trial data indicated that no SmartPlugs were lost in a six-month period in contrast to a few losses of the Freeman tapered-shaft variety.
Consider this: With intracanalicular plugs, how do you know whether the plugs are still in the canaliculus? Lacrimedics has been diligently working on this issue.
Figure 3. The WIPPT allows precise positioning of Herrick
Lacrimedics' "blue" opaque plug replaces its predecessor, the white opaque Herrick plug. Transillumination of the canalicular area with an opaque plug in place reveals a "shadow" of the plug. The coloration of the blue plug allows viewing of plug position with slight lid eversion, even without transillumination. The patient can then also monitor plug retention, especially of the lower lid.
Positioning of the Herrick plug is also important. The company has developed a plug positioning tool (WIPPT) (Figure 3) that allows precise positioning of the plug in the horizontal canaliculus. Correct placement promotes retention and minimizes irritation from a plug rubbing on the inner side of the puncta.
Using Logic to Manage Dry Eye
Determining the appropriate steps for managing contact lens-related dry eye can prove challenging. Remember to assess symptoms, contact lens fit, environment, lid disease, solutions, wearing time and rewetting drop use before initiating changes.
Most practitioners manage lid disease, refit the lens, recommend more frequent lens replacement, change the care system and add punctual occlusion before reducing lens wear time and adding medical management such as nutritional supplements, artificial tear formulations and prescription medications.
Dr. Nichols is an assistant professor of clinical optometry at The Ohio State University College of Optometry in the area of dry eye research.