Placebo administration for dry eye disease: a level I evidence based systematic review and meta-analysis

Two-Year Progression of Dry Eye Disease in Dry Eye Assessment and Management Study

PURPOSE

The purpose of this study was to evaluate the progression of dry eye disease (DED) symptoms and signs over 2 years through a secondary analysis of data collected from the Dry Eye Assessment and Management study.

METHODS

Participants who were assigned to omega-3 fatty acid in the first year were rerandomized in the second year to either continue with omega-3 fatty acid or switch to placebo. At baseline, 3, 6, 12, 18, and 24 months, DED symptoms were evaluated by using the Ocular Surface Disease Index and the Brief Ocular Discomfort Index (BODI). DED signs were assessed using conjunctival staining, corneal staining, tear break-up time, Schirmer testing, and keratography measures. Medication usage was documented at each visit. Because the treatment and placebo groups displayed no statistical differences in both signs and symptoms, data from the 43 participants were combined to assess longitudinal changes in symptoms and signs.

RESULTS

At 3 months after omega-3 fatty acid treatment, there were significant improvements from baseline in Ocular Surface Disease Index and Brief Ocular Discomfort Index scores (all P ≤ 0.002) and less use of artificial tears or gel ( P = 0.02), but between 3 and 24 months, no significant changes in symptoms and treatments were observed ( P ≥ 0.06). Except for a significant improvement in conjunctival staining score over 2 years ( P = 0.001), there were no significant sign changes in corneal staining ( P = 0.32), tear break-up time ( P = 0.43), Schirmer test ( P = 0.09), and additional measures (all P ≥ 0.07).

CONCLUSIONS

We did not observe a progression of DED signs or symptoms over a 2-year period, except for a probable placebo response in symptoms in the first 3 months and an improvement in conjunctival staining score.

Effects of Carboxymethylcellulose Artificial Tears on Ocular Surface Microbiome Diversity and Composition, A Randomized Controlled Trial

Purpose

Carboxymethylcellulose is an artificial tear ingredient known to decrease gut microbiome diversity when ingested. This study examines the effect of carboxymethylcellulose on ocular surface microbiome diversity and composition.

Methods

Healthy adult participants without significant ophthalmic disease or concurrent carboxymethylcellulose artificial tear use were allocated randomly to take carboxymethylcellulose or control polyethylene glycol artificial tears for seven days. Conjunctival swabs were collected before and after artificial tear treatment. This trial is registered at clinicaltrials.gov (NCT05292755). Primary outcomes included abundance of bacterial taxa and microbiome diversity as measured by the Chao-1 richness estimate, Shannon's phylogenetic diversity index, and UniFrac analysis. Secondary outcomes included Ocular Surface Disease Index scores and artificial tear compliance.

Results

Of the 80 enrolled participants, 66 completed the trial. Neither intervention affected Chao-1 richness (analysis of variance [ANOVA], P = 0.231) or Shannon's diversity index (ANOVA, P = 0.224). Microbiome samples did not separate by time point (permutation multivariate analysis of variance [PERMANOVA], P = 0.223) or intervention group (PERMANOVA, P = 0.668). LEfSe taxonomic analysis revealed that carboxymethylcellulose depleted several taxa including Bacteroides and Lachnoclostridium, but enriched Enterobacteriaceae, Citrobacter, and Gordonia. Both interventions decreased OSDI scores (Wilcoxon signed rank test, P < 0.05), but there was no significant difference between interventions (Mann-Whitney U, P = 0.54).

Conclusions

Carboxymethylcellulose artificial tears increased Actinobacteriota but decreased Bacteroides and Firmicutes bacteria. Carboxymethylcellulose artificial tears do not affect ocular surface microbiome diversity and are not significantly more effective than polyethylene glycol artificial tears for dry eye treatment.

Translational Relevance

The 16S microbiome analysis has revealed small changes in the ocular surface microbiome associated with artificial tear use.

Possible Strategies to Mitigate Placebo or Vehicle Response in Dry Eye Disease Trials: A Narrative Review

Many candidate drugs for dry eye disease (DED) have been assessed over the years in pursuit of demonstrating efficacy in both signs and symptoms. However, patients with DED have very limited treatment options for management of both signs and symptoms of DED. There are several potential reasons behind this including the placebo or vehicle response, which is a frequent issue observed in DED trials. A high magnitude of vehicle response interferes with the estimation of a drug's treatment effect and may lead to failure of a clinical trial. To address these concerns, Tear Film and Ocular Surface Society International Dry Eye Workshop II taskforce has recommended a few study design strategies to minimize vehicle response observed in DED trials. This review briefly describes the factors that lead to placebo/vehicle response in DED trials and focuses on the aspects of clinical trial design that can be improved to mitigate vehicle response. In addition, it presents the observations from a recent ECF843 phase 2b study, wherein the study design approach consisted of a vehicle run-in phase, withdrawal phase, and masked treatment transition, and led to consistent data for DED signs and symptoms and reduced vehicle response post randomization.

Chloroquine and Hydroxychloroquine in the Treatment of Dry Eye Disease

The role of chloroquine (CQ) and hydroxychloroquine (HCQ) in the management of dry eye disease is still unclear. This systematic review and meta-analysis investigates the efficacy and feasibility of CQ and HCQ in patients with dry eye disease. In February 2023, PubMed, Embase, Google Scholar, and Web of Science were accessed. Data from 462 patients (mean age 54.4 ± 2.8 years) were collected. Compared to baseline, the tear breakup time (p < 0.0001) and Schirmer I test (p < 0.0001) were significantly increased, and the Ocular Surface Disease Index (OSDI, p < 0.0001) and corneal staining (p < 0.0001) were significantly decreased at the last follow-up in the CQ/HCQ group. At the last follow-up, the OSDI was significantly lower in the CQ/HCQ group compared to the control group (p < 0.0001). Corneal staining was significantly greater in the control group compared to the CQ/HCQ group (p < 0.0001). The Schirmer I test showed no significant difference between the groups (p = 0.2). Altogether, CQ and HCQ improved the symptoms and signs of dry eye disease.