Informed consent was obtained from each patient prior to participation in the study. The study was conducted in accordance with the ethical principles specified in the Declaration of Helsinki and Good Clinical Practice Guidelines. It was approved by the institutional review board (IRB) (IRB No: XC16MIMV0056S) before study initiation. Because this study was conducted at multiple clinical centers, IRB approval was acquired from each center. Additionally, this trial was registered on the Current Research Information System (CRIS) (http://cris.nih.go.kr) and World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP, www.who.int/ictrp). The trial registration number is KCT0002180.
Study design
This is a multicenter (12 centers), randomized, evaluator-masked study. A total of 154 patients with moderate DED who had received a screening test were enrolled. The 153 eligible patients were randomly allocated to receive 0.05% cyclosporine ophthalmic nanoemulsion (CN group) or 3% diquafosol ophthalmic solution (DQ group). Patients in the CN group instilled 0.05% cyclosporine (Cyporin N; Taejoon Pharmaceutical Inc., Seoul, Korea) twice daily. Patients in the DQ group instilled 3% diquafosol six times daily. To prevent bias from the difference in the total number of eye drops per day, patients in the CN group were asked to instill 0.15% hyaluronic acid ophthalmic preparation (New Hyaluni; Taejoon Pharmaceutical Inc., Seoul, Korea) four times a day. Both groups were allowed to instill it ad libitum when they felt discomfort; they were told the total daily number of instillations should not exceed six per day as possible.
The patients were examined 4, 8, and 12 weeks after the initiation of treatment. At 4 and 12 weeks after treatment, both efficacy and safety were evaluated. At 8 weeks, only Ocular Surface Disease Index (OSDI) symptoms, adherence, and safety were evaluated.
Study population
Adult patients (age: ≥19 years) were eligible for participation if they had been diagnosed with moderate DED according to the following criteria: (1) symptomatic dry eye with complaint of ocular dryness, (2) cornea fluorescein staining ≥ 4 on the National Eye Institute (NEI) scale, and (3) tear break-up time (TBUT) ≤ 10 sec. Exclusion criteria were as follows: (1) patients who had used cyclosporine or diquafosol systemically or topically within 4 weeks of the screening period; (2) patients who had used topical agents to treat another ocular disease (glaucoma, allergy, infection, etc.) within 4 weeks of the screening period; (3) patients who had used any drug that might influence the state of DED within 4 weeks of the screening period; (4) patients with Sjögren syndrome; (5) patients who needed to use contact lenses during the study period; (6) patients with an eyelid disease (e.g., trichiasis and entropion), or anterior ocular disease (herpes keratitis, cicatricial pemphigoid, pterygium, neurotrophic keratitis, keratoconus etc.) and who had undergone an ocular operation (punctal plug or nasolacrimal drainage process) within 4 weeks of the screening period; and (7) patients with hypersensitivity to drugs or patients who were pregnant.
Randomization
An independent statistical office (Seoul CRO, Co., Ltd.) performed the permuted stratified block randomization for sequence generation using SAS 9.2 (SAS institute Inc., Cary, NC, USA), with participating centers as the strata. The random sequence was sent to each center via an interactive web-based response system (IWRS) to ensure allocation concealment during the full study period.
All medications were provided to patients after re-packaging them in an aluminum pouch and container box with coded product information. This was to maintain the masked condition, as the medications were of different shapes and required different doses. Patients were also prohibited from talking of drug-related topics to efficacy evaluators; other designated study member(s) assisted the patients with those things, including a patient diary.
Assessment of outcome measure
Efficacy assessment
The primary efficacy endpoint of this trial was defined as the change in score on the NEI scale of corneal and conjunctival staining from baseline to 12 weeks after treatment. The secondary efficacy endpoints were defined as the change in score on the NEI erosion scale, Schirmer’s test value, TBUT, and OSDI scores at weeks 4 and 12. However, to determine satisfaction and adherence, OSDI scores were measured at 8 weeks as well as 4 and 12 weeks. According to the National Eye Institute/Industry Workshop report [13], corneal and conjunctival staining was evaluated under a slit-lamp microscope with a cobalt blue filter (scale: 0–33). The cornea was divided into five sections: center, nasal, temporal, superior, and inferior. While the patient blinked normally, 5 μL of 2% fluorescein solution was instilled in the conjunctival sac. Fluorescein was scored based on 0 to 3 points of the NEI scale at each section (scale from 0 to 15). Conjunctiva was divided into six sections: three sections on the nasal side and three sections on the temporal side. Then, 20 μL of 1% lissamine green solution was instilled in the conjunctival sac. Conjunctival staining was evaluated under low illumination and also scored based on 0 to 3 points of the NEI scale at each section (scale: 0-8).
For the TBUT, after corneal staining with 5 μL of 2% fluorescein solution, the time between a normal blink and the first appearance of a dry spot in the tear film was measured. The average of three repeated measurements was recorded. For the Schirmer’s test, the lacrimal function, including physiologically basic and reflective lacrimal secretion, was evaluated. Without anesthesia, the Schirmer’s test strip was placed on the temporal third of the lower eyelid between the lower palpebral conjunctiva and the lower bulbar conjunctiva. After 5 min, the length of the tear fluid absorbed on the strip was measured in millimeters.
To assess instillation adherence, all the patients were instructed to record the number of drops they used of the investigational drug and lubricant daily in a patient diary and to bring their records on each visit. We assessed and compared the satisfaction of these trial drugs through a survey regarding the sensation of the eye drops upon instillation scored on a 10-point visual analog scale. The sensation was classified as overall satisfaction, burning, stinging, blurring, stickiness, smoothing, or moisturizing.
Safety assessment
The safety variable was the occurrence of adverse events (AEs), determined during various visits based on physical signs and symptoms, an external eye examination, slit-lamp microscopy, visual acuity, intraocular pressure, and funduscopy.
Statistical analysis
Power analysis was performed to justify the number of patients enrolled in the study. All statistical analyses were performed using SAS 9.4 (SAS institute Inc., Cary, NC, USA). The data were collected on both eyes treated with the study drug, and, to evaluate efficacy, data on the “worse” eye, defined as the eye with a worse baseline corneal and conjunctival staining score, were included. Data on both eyes were also included to evaluate safety. In the case that both eyes had compatible baseline corneal and conjunctival staining scores, the right eye was used as the worse eye.
Descriptive statistics (mean ± standard deviation, min, max) were used to summarize most efficacy data, including the primary endpoint, corneal and conjunctival staining, and frequency distribution for several categorical variables (safety, instillation adherence). The Wilcoxon signed-rank test was used to analyze within-group changes. For intergroup comparisons, the Wilcoxon rank-sum test was used. The general linear model (GLM) was used to test the significance of each group, time, and their interaction (group by time), where the interaction between groups over time was the key outcome (repeated measure ANOVA). For the assessment of safety, intergroup differences were analyzed using a Chi-square test.
The full analysis set (FAS) was defined as all randomized patients with the primary efficacy data; the per protocol set (PPS) included all eligible patients without major protocol deviations and with all efficacy data. The PPS was the primary population for all efficacy analyses. The FAS was used for confirmatory purposes. The safety set comprised all patients who, according to their patient diary, received the study treatment at least once.