How punctal plugs may influence tear osmolarity and aid in dry eye therapies

Tear osmolarity decreases with punctal plug insertion and serves as a leading indicator of therapeutic efficacy in dry eye disease.

Take-home message: Tear osmolarity decreases with punctal plug insertion and serves as a leading indicator of therapeutic efficacy in dry eye disease.

Reviewed by Jay S. Pepose, MD, PhD

St. Louis-Aside from serving as an artificial barrier to loss of tears, punctal plugs may also have an effect on tear osmolarity, said Jay S. Pepose, MD, PhD.

A recent study indicated tear osmolarity scores dropped by more than 10 mOsm/L in almost 50% of the patients tested, said Dr. Pepose, professor of clinical ophthalmology and visual sciences, Washington University School of Medicine, St. Louis.

In a prospective clinical trial of patients with dry eye conducted at a few sites, Dr. Pepose and colleagues sought to determine first, how punctal occlusion affected tear osmolarity and second, the effect of the occlusion on the severity and frequency of symptoms, tear break-up time (TBUT), corneal staining, and meibomian gland dysfunction (MGD).

Twenty-eight subjects were included in the study. All had been diagnosed previously with dry eye and tear film hyperosmolarity (>308 mOsm/L).

In addition to a clinical evaluation that included measurement of the tear osmolarity, symptoms, and a slit-lamp evaluation to determine the TBUT, cornea/conjunctiva staining grade, and MGD, the patients also were asked to complete the Visual Analogue Scale questionnaire. This determined the frequency and severity of symptoms on a scale of 0 indicating no symptoms and 10 indicating high symptoms.


Patients were evaluated at four time points-baseline, 30 days, 60 days, and 90 days after the start of the study-and were randomly assigned to one of two treatment groups:

  • group A, in which punctal plugs were inserted during the second evaluation in 12 subjects; and

  • group B, in which sham treatment was administered during the second visit and punctal plugs were inserted during the third evaluation in 16 subjects.

Dr. Pepose reported no difference in the baseline tear osmolarity, symptoms, or other dry eye signs between the two groups.

At visit 3, the patients with punctal plugs (group A) had a mean reduction in osmolarity from baseline of –8.5 ± 16.42 mOsm/L including four of 12 subjects with reduction in osmolarity of more than 10 mOsm/L (mean, –21.75 ± 13.22 mOsm/L).

In group B, no decrease in tear osmolarity was seen during sham treatment. However, following punctal plug insertion, nine of 16 subjects had a decrease of over 10 mOsm/L (mean, –21.89 ± 11.29 mOsm/L).

At visit 4, no clinically relevant changes were seen in the other parameters measured between the two treatment groups.

Following punctal plug treatment, 13 of 28 subjects had a reduction in osmolarity of over 10 mOsm/L, four patients in group A and nine patients in group B. Eight of the total 56 eyes had a reduction in corneal staining by one grade, five eyes in group A and three eyes in group B. Six of eight eyes that had reduced staining also had reduced osmolarity by 10 mOsm/L, according to Dr. Pepose.


“Punctal plugs help retain tears on the ocular surface to help alleviate dry eye disease,” he said. “However, the study cohort varied in their chronicity and severity of dry eye disease in addition to difference in the therapies used. As a result, the change in different dry eye signs and symptoms is expected to be different across the study subjects.”

Tear osmolarity may be a leading indicator of therapy efficacy in DED with punctal plug insertion. Thirteen of the 28 patients had reduced osmolarity over 10 mOsm/L.

Only eight of the total 56 eyes had a reduction in staining. The changes in the symptoms score were similar between the treatment and sham groups. There were no significant changes in meibomian gland function or lid grading.

Tear osmolarity provides an objective quantitative value that can aid the physician to determine/track therapeutic efficacy and counsel the patient to ensure compliance to therapy. Data from a larger sample size with longer follow-up is needed to quantify changes in conventional dry eye signs and symptoms with effective therapy.


Jay S. Pepose, MD, PhD


This article was adapted from Dr. Pepose’s presentation at the 2015 meeting of the American Society of Cataract and Refractive Surgery. Dr. Pepose is a consultant for TearLab. Dr. Pepose was joined in this study by Douglas Devries, OD, and Brian Townsend, OD.

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