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Studies find negligible difference between upper, lower occlusion
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PHILADELPHIA — Findings by Robert Herrick, MD, prompted two recent studies on site selection for punctal occlusion, both of which were presented here at the American Academy of Optometry meeting in December.
“I had heard that Dr. Herrick recommends plugging the upper puncta first, because you get equal coverage or improvement in retarding the evacuation of tears,” said John Sharpe, OD, a professor at the Southern College of Optometry, who conducted one of the studies. “This just flies in the face of general wisdom, which says to plug the lowers first. Given the literature and the common knowledge, we just started scratching our heads. That is basically what gave rise to the study.”
While Dr. Herrick’s theory prompted these studies, it is important to note that his conviction relates specifically to the placement of intracanalicular plugs.
Study by Drs. Sharpe, Connor
The study conducted by Dr. Sharpe and Charles Connor, PhD, OD, FAAO, examined 20 subjects with symptomatic dry eye who were considered candidates for punctal occlusion with Odyssey punctum plugs based on Schirmer’s test results.
The subjects, 15 women and five men, ranged in age from 23 to 60 years of age, with a mean age of 28.35 years. Prior to punctal plug insertion, a tear break-up time (TBUT), rose bengal staining and Schirmer’s test were performed. Selection of the puncta to be occluded was based on the subject’s enrollment number. The odd number subjects had the upper right and lower left puncta occluded while the even number subjects had the upper left and lower right puncta occluded.
One week after insertion, the subjects were retested as before and given a comfort questionnaire.
Most said lower felt better
Four of the original subjects were unable to complete the study due to mechanical irritation. Of the 16 who completed the study, 10 reported that the eye with the lower puncta occluded felt better than the eye with the upper puncta occluded. The remaining six subjects said that both eyes felt better and did not appreciate any difference between the two eyes.
“None of the subjects reported that the eye with the upper puncta occluded felt better,” Dr. Sharpe said.
The study examined epiphora as well. Two of the subjects with punctum plugs had epiphora, one with upper occlusion and one with lower occlusion. Three subjects had improvement in rose bengal staining after occlusion. The TBUT increased slightly from 4.1 seconds pre-insertion to 4.41 seconds post-insertion.
“Based on the results, it does not appear that occlusion of the upper puncta provides any better symptom relief or is less likely to cause epiphora than the occlusion of the lower puncta,” Dr. Sharpe said.
Study by Dr. Ward
Also exploring the question of site selection for punctal occlusion was H. Jeffries Ward, OD, of the New England College of Optometry. Dr. Ward’s study specifically made this comparison in relation to contact lens wearers with dry eye symptoms.
“Basically, there has been a lot of controversy in the vision care profession relating to which is the best method, occluding the superior punctum or the inferior,” Dr. Ward said. “Dr. Herrick has claimed that superior occlusion provides better relief of symptoms related to dry eye. So, you have the traditional view vs. this new view as to what is the most effective procedure.”
Dr. Ward’s study followed an 8-week, prospective, placebo-controlled study design. A total of 10 subjects, eight women and two men, were recruited based on specific signs and symptoms of dry eye with hydrogel contact lens wear. TBUT, tear production, fluorescein and lissamine-green staining were monitored throughout the study, as were the symptoms of dryness, lens awareness and blur.
After baseline levels of these signs and symptoms were established, one previously randomized eye was chosen to serve as the treatment eye, with the other eye serving as a control. Both superior and inferior silicone punctal occlusion (with Tears Naturale punctum plugs by Alcon) were performed separately in the treatment eye, with a washout period between treatment methods.
Neither method is more effective
The study found that both superior and inferior punctal occlusion significantly diminish the symptoms associated with dry eye in hydrogel contact lens wearers. Direct statistical comparisons, however, showed that neither treatment method is more effective in reducing these symptoms.
While improvements in fluorescein corneal staining and lissamine-green bulbar staining approached clinical significance following superior occlusion, TBUT, tear production, fluorescein bulbar staining and lissamine-green corneal staining appeared to be unaffected by either method.
“In summary, I found no significantly clinical difference between superior and inferior punctal occlusion,” Dr. Ward said. “I should emphasize that this was a small-scale preliminary study, as opposed to a larger definitive study. But the overall result was that both methods significantly reduced all of the symptoms (awareness, blur and dry eye) with respect to the control eye, but neither method was shown to be more effective in its ability to reduce these symptoms.”
Dr. Ward said while the symptoms were significantly reduced, the signs were not affected in any clinically significant way. He emphasized that even if larger studies substantiate these findings, this does not necessarily mean that inferior occlusion should be the prevalent method.
“Many eye care professionals always occlude the lower puncta simply because they find it to be an easier method than superior occlusion. However, you really want to occlude the punctum that is least likely to abrade the conjunctiva,” he said. “In other words, if you look at the eye and you see that the lower eyelid is turned in more than the upper eyelid, it is probably a better idea to occlude the superior punctum, because it is going to be less likely to irritate the patient.”
“Dr. Herrick’s comments are based on the studies of numerous researchers using high-speed video and tear film interferometry,” according to Paul A. Williams, OD, medical advisor for Lacrimedics Inc., which manufactures the Herrick plug. “This shows the outflow process to be an active one, with a greater volume via the upper excretory system vs. the lower.
“There are concerns in using surface-style plugs: the irritation, reflex tearing and plug loss may negate the benefit of occlusion,” he continued. “This specific concern for abrasion of the eye and significant spontaneous plug loss with surface-style punctum plugs is what led Dr. Herrick to develop the lacrimal plug.”
For Your Information:
- John Sharpe, OD, is a professor at the Southern College of Optometry in Memphis, Tenn. He can be reached at 1245 Madison Ave., Memphis, TN 38104; (901) 722-3263; fax: (901) 722-3342; e-mail: jsharpe@sco.edu.
- H. Jeffries Ward, OD, is an optometrist and contact lens specialist based in Aurora, Colo. He can be reached at 2203 S. Peoria St., Aurora, CO 80014; (303) 369-2020; fax: (303) 369-9398.
- Paul A. Williams, OD, is a medical advisor for Lacrimedics Inc. and can be reached at the Dry Eye Treatment and Research Center, 112 131st St. South, Tacoma, WA 98444; (253) 537-7544.