Plain English Summary
Background and study aims
Studies show that preservatives in eye drop can trigger an inflammatory response. To the best of our knowledge, there is no report comparing the effects of preservative-free and preserved eye drops in dry eye syndrome. This study compares the antioxidants and inflammatory responses in tears of patients with dry eye syndrome treated with preservative-free eye drops versus eye drops with preservatives.
Who can participate?
21 years of age and over and diagnosed with dry eye syndrome.
What does the study involve
Participants were randomly allocated to receive either preservative-free eye drops or eye drops with preservatives. Various assessments will be carried out at the start of the study and at 1, 2 and 3 months after treatment.
What are the possible benefits and risks of participating?
Both preservative-free and preserved eye drops treatments may lead to significant improvement in symptoms of dry eye. There is no risk to participants.
Where is the study run from?
Bucheon St Mary's Hospital, South Korea.
When is the study starting and how long is it expected to run for?
The study started in September 2012 and ran until December 2013.
Who is funding the study?
National Research Foundation of Korea (NRF).
Who is the main contact?.
Professor Eun Chul Kim
Comparison of antioxidant and inflammatory cytokine activities in tears of patients with dry eye syndrome treated with preservative-free vs preserved eye drops
Dry eye syndrome is recognized as a highly prevalent inflammatory disease of the lacrimal functional unit caused by multifactorial reasons. Increase of the oxidative stress status in the conjunctiva of Sjogren syndrome patients appears to have a role in the pathogenesis of dry eye disease. Preservatives in eye drops can induce oxidative stress and inflammatory response in conjunctival epithelial cells and the rabbit dry eye model.
Institutional Review Board at the Bucheon St. Mary's Hospital, 21/08/2013
Randomized comparative clinical trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Dry eye syndrome
Permuted blocks were obtained using a computer-based random code generator (Research Randomizer; http://randomizer.org/).
50 patients (Group 1) were treated four times with preservative-free 0.1% sodium hyaluronate and 0.1% fluorometholone for the first month and preservative-free 0.1% sodium hyaluronate and 0.05% cyclosporine for the second and third month.
50 patients (Group 2) were treated four times with preserved 0.1% sodium hyaluronate and preserved 0.1% fluorometholone for the first month and preserved 0.1% sodium hyaluronate and 0.05% cyclosporine for the second and third month.
Following instillation of the eye drops, symptoms and signs of dry eye are measured.
Total duration of treatment and follow-up for each study arm: 3 months
Primary outcome measure
1. Ocular surface disease index (OSDI)
2. Corneal fluorescein staining
3. Schirmer tear test (without anesthesia)
4. Tear film break-up time (tBUT)
5. Symptom score of dry eye
6. Impression cytology
Measured at baseline, 1, 2 and 3 months.
Secondary outcome measures
Antioxidant and Inflammatory cytokine activities in tears measured by ELISA at baseline, 1, 2 and 3 months.
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Eligible patients were at least 21 years of age and had a diagnosis of dry eye syndrome refractory to conventional management. Inclusion criteria were:
1. Schirmer test (without anesthesia) of 5 mm/5 minutes in at least one eye
2. Low tear film break-up time (tBUT) (<5 seconds)
3. Mild superficial punctate keratitis, defined as a corneal punctate fluorescein staining score of ≥1 in either eye (scale 0 [none] to 3 [severe]); and one or more moderate (≥2) dry eye related symptoms, including itching, burning, blurred vision, foreign body sensation, dryness, photophobia, soreness, or pain.
Target number of participants
Group 1 (50 patients) was treated with preservative-free eye drops and group 2 (50 patients) was treated with preserved eye drops.
Participant exclusion criteria
Patients were excluded if they had:
1. A history of any ocular disorder including injury, infection, non-dry-eye ocular inflammation, trauma, or surgery within the prior 6 months
2. Were receiving concurrent treatment that could interfere with interpretation of the study results
3. Had any uncontrolled systemic disease or significant illness; or were pregnant, lactating, or considering becoming pregnant.
4. Patients could be discontinued before the completion of the study because of adverse events, pregnancy, protocol violations, lack of efficacy, or administrative or personal reasons.
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Bucheon St. Mary's Hospital
The National Research Foundation of Korea (NRF) (Korea, South)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)