
==== Front
BMC Ophthalmol
BMC Ophthalmol
BMC Ophthalmology
1471-2415
BioMed Central London

39251947
3620
10.1186/s12886-024-03620-5
Research
Effectiveness of cyclosporine nanoemulsion eye drops in patients with mild-to-moderate dry eyes: objective and subjective evaluation
Moon Su Young 1
Chung Ho Seok 12
Lee Jae Hyuck 1
Lee Hun 1
Tchah Hungwon 1
Kim Jae Yong jykim2311@amc.seoul.kr

12
1 grid.267370.7 0000 0004 0533 4667 Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505 South Korea
2 https://ror.org/02c2f8975 grid.267370.7 0000 0004 0533 4667 Department of Ophthalmology, Graduate School, University of Ulsan College of Medicine, Ulsan, South Korea
9 9 2024
9 9 2024
2024
24 40113 1 2023
6 8 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Background

To compare and evaluate objective and subjective clinical parameters between 0.05% cyclosporine nanoemulsion (CsN) and 0.15% hyaluronic acid (HA) administration in patients with mild-to-moderate dry eyes.

Methods

In this prospective, randomized, double-masked, single-center, and placebo-controlled parallel study, patients with mild-to-moderate dry eyes were randomly allocated to be treated with 0.05% CsN or 0.15% HA twice daily. Patients were followed-up at 4, 8, and 12 weeks. Objective and subjective parameters were evaluated during each visit.

Results

A total of 35 patients were enrolled in this study. Compared with baseline, tear film break-up time and fluorescein staining scores at 4, 8, and 12 weeks significantly improved in the CsN group. However, the Schirmer I test showed no statistically significant change until week 12. Using the Symptom Assessment in Dry Eye (SANDE) score, both groups gradually showed significant improvement compared with baseline values. However, the Dry Eye-Related Quality-of-life Score Questionnaire (DEQS) showed no statistically significant change during the treatment period.

Conclusions

Both 0.05% CsN and 0.15% HA administration twice a day effectively improved the objective signs and subjective symptoms of patients with mild-to-moderate dry eyes. However, patients treated with 0.05% CsN experienced greater and faster improvement.

Keywords

Cyclosporine
Dry eye
Symptom Assessment in Dry Eye (SANDE)
Dry Eye-Related Quality of life score (DEQS)
http://dx.doi.org/10.13039/501100003725 National Research Foundation of Korea NRF-2018R1D1A1B07043010 http://dx.doi.org/10.13039/501100005006 Asan Institute for Life Sciences, Asan Medical Center 2020IL0023 issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcBackground

Dry eye is a multifactorial disease of the ocular surface characterized by loss of tear film homeostasis accompanied by ocular symptoms. Tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities are important etiological factors [1]. Several treatments have been developed to manage inflammation in dry eye diseases, including administration of cyclosporine A, which acts as an anti-inflammatory factor by inhibiting calcineurin. This inhibition leads to improvement in tearing, protection of epithelial cells, and inhibition of goblet cell loss [2–5]. Moreover, cyclosporine A has a better long-term safety profile compared with corticosteroids. However, due to its large molecular weight and hydrophobic nature, administration of cyclosporine A with conventional topical ophthalmic delivery methods has proven challenging [6, 7]. Anionic oil-in-water emulsion has been widely used over decades, but is often associated with side effects, including visual disturbance and conjunctival hyperemia [8]. To maximize ocular bioavailability, various drug delivery methodologies have been developed [9].

The self-nanoemulsifying drug delivery system is a transparent anhydrous homogenous mixture diluted in water that provides better chemical and physical stability, as well as increased efficacy [6, 7, 10]. However, there is a lack of prospective studies evaluating the objective and subjective parameters that validate the safety and efficacy of 0.05% cyclosporine nanoemulsion (CsN) in patients with mild-to-moderate dry eyes.

Recently, hyaluronic acid (HA) has been widely used to treat dry eye disease. HA treatment has been reported to improve both signs and symptoms of dry eye disease in most cases [11–13]. Therefore, in this randomized, double-masked, single-center, and placebo-controlled parallel study, the improvement in symptoms of dry eyes were evaluated and compared between 0.05% CsN and 0.15% HA administration for 12 weeks. Considering individual differences in symptoms, various types of questionnaires with different questions have been developed to comprehensively evaluate dry eye disease [14]. Three questionnaires were implemented in the present study, and correlations between them were analyzed.

Methods

This study was conducted according to the ethical guidelines outlined in the Declaration of Helsinki and the Good Clinical Practice Guidelines. Written informed consent was obtained from all patients before the start of the study, and power analysis was performed to justify the number of enrolled patients. The study protocol and informed consents were reviewed and approved by the institutional review board of Asan Medical Center at the University of Ulsan in Seoul (Approval number: 2019 − 0884).

Study design

This was a prospective, randomized, double-masked, single-center, and placebo-controlled parallel study comparing 0.05% CsN (Cyporin N, Taejoon, Inc., Seoul, Korea) with 0.15% HA administration (New Hyaluni, Taejoon, Inc.) over a 12-week treatment period in patients with mild-to-moderate dry eyes. The study was conducted from November 2019 to July 2020. Participants were requested to discontinue administration of any topical eye drops, including artificial tears, and entered a 4-week washout period. Eligible patients were then randomized with an allocation ratio of 1:1 to receive either 0.05% CsN or 0.15% HA and instructed to apply one drop of the assigned medication twice daily for 12 weeks. Randomization for the enrollment order at the ophthalmology clinic was performed using computer-generated random allocation. Both the patients and caregivers were blinded to the intervention. Efficacy and safety were assessed at 4, 8, and 12 weeks. Sample size estimation was performed using the SAS software v.9.4 (SAS Institute Inc., Cary, NC, USA). Initially, a sample size of 42 patients was determined to achieve 80% power to detect a significant difference between two independent groups, with a type I error of 0.05. Despite the inclusion of 35 patients in this study, the calculated power was sufficiently high at 75%, indicating adequate sensitivity for detecting differences.

Study cohort

Inclusion criteria were as follows: (1) diagnosis according to the Korean Corneal Disease Study Group under level I or II and (2) corneal fluorescein staining score according to the National Eye Institute (NEI) scale ≤ 6 points and (3) over 19 years old [15]. In the classification established by the Korean Corneal Disease Study Group, Level I or II includes patients with mild to moderate dry eye disease. Specifically, Level I dry eye comprises patients who experience symptoms sometimes, have an Oxford staining score below Grade I, and exhibit variable results for tear breakup time and the Schirmer-1 test. Level II dry eye includes patients who have symptoms often, an Oxford staining score Grade II, tear breakup time between 6 and 10 s, and Schirmer-1 test between 5 and 10 mm. Exclusion criteria included a history of refractive corneal surgery, contact lens use, Stevens–Johnson syndrome, ocular cicatricial pemphigoid, or chemical or thermal burns. Patients with a history of previous ocular surgery, proven or suspected glaucoma or ocular hypertension, those who were pregnant, and those taking systemic medications that might affect tear secretion were also excluded. When both eyes of the patient met the inclusion criteria, only the eye with more severe symptoms was included. The right eye was included when patients had the same severity of dry eye symptoms in both eyes.

Ocular surface evaluation: objective parameters

The tear film break-up time (TBUT), NEI scale for grading fluorescein staining, and Schirmer I test without anesthesia were assessed at baseline and at weeks 4, 8, and 12. Matrix metalloproteinase 9 (MMP-9; InflammaDry®, Quidel Corp., San Diego, CA) tests were performed at baseline and at week 12 (final visit).

Patients were instructed to blink several times for a few seconds to ensure adequate mixing of the dye. TBUT was measured three times with a stopwatch, and the mean value was then calculated. The Schirmer I test without anesthesia was performed by placing a strip in each eye and recording the part of the strip (measured in mm) that became wet after 5 min. The ocular surface was initially stained with 2-µL 2% preservative-free fluorescein solution instilled into the conjunctival sac using a micropipette. Corneal fluorescein staining was assessed for each of the five regions of the cornea (central, superior, inferior, nasal, and temporal) using a 0-to-3 scale (0 = no punctate staining; 3 = severe diffuse or coalescent macropunctate staining) for each region. The score for each region was summed to acquire the total corneal staining score (range, 0–15).

Extracellular MMP-9 secretion is induced during the early stages of the inflammatory cascade, and it promotes migration of inflammatory cells to the ocular surface. Therefore, elevated MMP-9 indicates the presence of clinically significant ocular surface inflammation, leading to tear film instability and dry eye [16]. MMP-9 in the eye was evaluated by the same trained technicians after dabbing of a sampling fleece along the palpebral conjunctiva of the patient’s lower eyelid until the device became saturated [17]. It was then placed into the sample transfer window of the test cassette body. Next, the technician immersed the absorbent tip in the buffer vial. Results were recorded and reviewed after 10 min. The existence of one blue line and one red line in the MMP-9 test result window indicated a positive test result (MMP-9 ≥ 40 ng/mL), while a single blue line indicated a negative test result (MMP-9 < 40 ng/mL) [18].

Evaluation of ocular symptoms: subjective parameters

Patients’ ocular symptoms were evaluated using dry eye questionnaires including Symptom Assessment in Dry Eye (SANDE) [19], Dry Eye-Related Quality-of-Life Score (DEQS) Questionnaire [20], and Ocular Discomfort Analog Scale (ODAS) [21] at baseline and weeks 4, 8, and 12.

SANDE includes two questions using a 100 mm horizontal linear visual analog scale (VAS). The measurement of symptom frequency ranged from “rarely” to “all of the time,” and symptom severity ranged from “very mild” to “very severe” [19].

The DEQS questionnaire was a 15-item instrument developed to assess six questions regarding subjective dry eye symptoms and nine on the effects on daily living activities within the previous week. Each question had columns A and B to denote the frequency and severity of symptoms, respectively. Responses to the frequency portion in column A were based on a five-point scale ranging from “none of the time” (no points) to “all of the time” (four points). A score between 1 and 4 points prompted the respondent to proceed to column B to answer questions regarding severity on a four-point scale. The Quality-of-Life Scale (QOLS), ranging from 0 to 100 points, was calculated by multiplying the total points in column B by 25 and dividing the result by the number of valid responses. QOLS was positively correlated with the severity of the subjective dry eye symptoms and their impact on daily life. The cut-off value for dry eye was 15 points [20].

The ODAS questionnaires included seven questions, including ocular discomfort during digital media use (sensitive to bright light, tightness, dry sensation, foreign body sensation, burning sensation, blurring, and fatigue) and ODAS8 for the time of eye discomfort onset during TV watching [7].

Correlation between symptomatic questionnaires

To validate the ODAS score, correlations between the data obtained from each questionnaire were analyzed [19].

Statistical methods

Data are shown as mean ± standard error. Monocular data analyses of eligible eyes were performed for statistical comparisons. Efficacy analyses of the ocular surface included assessment of the statistical significance of the change in TBUT, corneal fluorescein staining score, and Schirmer I test at 4, 8, and 12 weeks. Symptomatic efficacy analyses assessed changes in symptomatic questionnaires. Correlations between questionnaires were also analyzed with the Pearson correlation coefficient. The Mann-Whitney test was used for comparison between groups, and the Wilcoxon signed rank test was used for comparison before and after treatment. Categorical variables were compared using the chi-square or Fisher’s exact test. Statistical analyses were performed using the SPSS software (version 18.0 for Windows; SPSS, Inc., Chicago, IL), and p < 0.05 was considered statistically significant.

Results

A total of 35 patients were enrolled in this study; however, three patients (one in the HA group and two in the CsN group) withdrew consent, and two patients in the CsN group discontinued treatment due to ocular discomfort. There were no statistically significant differences in the background characteristics and baseline parameters between the two groups (Table 1).

Table 1 Characteristics and Baseline Data of the study cohort

	HA 0.15%
(n = 15)	CsN 0.05%
(n = 15)	P value	
Disposition	16	19		
Completed the study (%)	15 (93.75%)	15 (78.95%)	1.000	
Subjects’ discontinuation (%)	1 (6.25%)	4 (21.05%)	0.523	
Reason for discontinuation, n (%)				
Withdrawal of consent by the patient	1 (100%)	2 (50%)	0.899	
Adverse events	0	2(50%)	0.655	
Demographics				
Sex, female	13 (86.67%)	14 (93.33%)	1.000	
Age, years	47.87 ± 16.92	41.13 ± 11.43	0.212	
VDT use time, hours/day	8.10 ± 1.54	11.13 ± 4.72	0.134	
Baseline Data				
Objective data

(Surface evaluation)

				
TBUT, seconds	4.68 ± 1.30	4.15 ± 1.62	0.328	
Staining score (NEI scale)	3.33 ± 2.35	3.27 ± 2.19	0.936	
Schirmer Test I, mm	6.00 ± 1.73	5.93 ± 1.03	0.899	
MMP-9 (negative/positive), n (%)	13 (86.67%) / 2 (13.33%)	14 (93.33%) / 1 (6.67%)	1.000	
Subjective data

(Symptomatic evaluation)

				
SANDE score	70.13 ± 24.96	72.70 ± 20.43	0.761	
DEQS (Ocular symptom)	41.67 ± 23.68	47.12 ± 12.54	0.459	
DEQS (Impact on Daily life)	39.68 ± 27.49	38.66 ± 10.89	0.899	
DEQS (Summary score)	40.47 ± 24.64	40.26 ± 11.98	0.977	
ODAS1-7	31.67 ± 16.17	25.46 ± 15.59	0.313	
ODAS8 (minutes)	51.43 ± 44.83	41.08 ± 32.64	0.502	
HA = Hyaluronic acid 0.15%; CsN = Cyclosporine Nanoemulsion 0.05%; VDT = Visual display terminal; TBUT = Tear Break-up Time; NEI = National Eye Institute; MMP-9 = Matrix Metalloproteinase-9; SANDE = Symptom Assessment in Dry Eye; DEQS = Dry Eye-Related Quality of life Score Questionnaire; ODAS = Ocular Discomfort Analog scale

Ocular surface findings

TBUT at weeks 4, 8, and 12 increased in both groups compared with the baseline. This increase was statistically significant at weeks 4, 8, and 12 in the CsN group (p = 0.004, 0.001 and < 0.001, respectively); however, significance was only observed at week 12 in the HA group (p = 0.004). In addition, there were no significant differences between the two groups until weeks 4 and 8 compared with baseline, but significance was evident between the two groups at week 12 (p = 0.004).

NEI staining scores at weeks 4, 8, and 12 decreased in both groups compared with baseline. In the CsN group, statistically significant reductions over baseline were observed at weeks 4, 8, and 12 (p = 0.007, 0.003, and < 0.001, respectively). However, in the HA group, no statistically significant reduction was observed at any time point. In addition, there was no significant improvement in the staining score between the two groups.

The results of Schirmer I test at weeks 4, 8, and 12 compared with baseline increased in both groups. In the CsN group, a statistically significant increase compared with baseline was observed only at week 12 (p = 0.005). Moreover, a significant increase was noted in the HA group at 8 weeks (p = 0.043). Significance differences were also observed between the two groups at 12 weeks (p = 0.042; Table 2; Fig. 1).

Fig. 1 Comparison between time points within groups and between the Hyaluronic acid group (dark gray) and the Cyclosporine A group (light gray) at 12 weeks. (A) tear break-up time (TBUT), (B) staining score by National Eye Institute (NEI) scale, and (C) Schirmer Test I without anesthesia. HA = Hyaluronic acid 0.15%; CsN = Cyclosporine Nanoemulsion 0.05%; *p < 0.05, **p < 0.001

The MMP-9 tests showed no significant difference between baseline and any follow-up period (Table 1). Only two patients in the HA group (13.33%) and one in the CsN group (6.67%) showed positivity for MMP-9, and all remained negative after the fourth week.

Table 2 Comparison of changes in TBUT, staining score (NEI scale), and unanesthetized Schirmer Test I between the hyaluronic acid and cyclosporine nanoemulsion groups

	HA 0.15%
(n = 15)	CsN 0.05%
(n = 15)	P value	
TBUT (s)				
Base line	4.68 ± 1.30	4.15 ± 1.62	0.328	
Week 4	5.44 ± 1.69	5.61 ± 1.91	0.793	
Baseline vs. Week 4	0.76 ± 1.39

(p = 0.052)

	1.47 ± 1.63

(p = 0.004)*

	0.212	
Week 8	5.57 ± 1.49	6.21 ± 1.97	0.321	
Baseline vs. Week 8	0.89 ± 2.00

(p = 0.108)

	2.07 ± 2.01

(p = 0.001)*

	0.119	
Week 12	5.72 ± 1.33	7.34 ± 1.94	0.012*	
Baseline vs. Week 12	1.04 ± 1.18

(p = 0.004)*

	3.20 ± 2.26

(p < 0.001)*

	0.004*	
Staining score

(NEI scale)

				
Base line	3.33 ± 2.35	3.27 ± 2.19	0.936	
Week 4	2.80 ± 2.57	2.07 ± 1.62	0.358	
Baseline vs. Week 4	-0.53 ± 2.47

(p = 0.418)

	-1.20 ± 1.47

(p = 0.007)*

	0.378	
Week 8	2.33 ± 2.16	2.07 ± 2.12	0.735	
Baseline vs. Week 8	-1.00 ± 2.51

(p = 0.145)

	-1.20 ± 1.32

(p = 0.003)*

	0.787	
Week 12	2.13 ± 2.07	1.40 ± 1.88	0.318	
Baseline vs. Week 12	-1.20 ± 2.34

(p = 0.067)

	-1.87 ± 1.68

(p < 0.001)*

	0.378	
Schirmer Test I (mm)				
Base line	6.00 ± 1.73	5.93 ± 1.03	0.899	
Week 4	7.07 ± 3.08	6.47 ± 1.55	0.508	
Baseline vs. Week 4	1.07 ± 2.84

(p = 0.168)

	0.53 ± 1.46

(p = 0.178)

	0.525	
Week 8	7.33 ± 2.85	7.33 ± 3.42	1.000	
Baseline vs. Week 8	1.33 ± 2.32

(p = 0.043)*

	1.40 ± 3.40

(p = 0.133)

	0.950	
Week 12	6.80 ± 2.08	9.07 ± 3.77	0.054	
Baseline vs. Week 12	0.80 ± 1.97

(p = 0.138)

	3.13 ± 3.68

(p = 0.005)*

	0.042*	
* Statistically significant (p < 0.05).

HA = Hyaluronic acid 0.15%; CsN = Cyclosporine Nanoemulsion 0.05%; TBUT = Tear Break-up Time; NEI = National Eye Institute.

Subjective parameters

Both groups showed significant improvement in SANDE score from baseline at all time-points except for the HA group at week 4 (4, 8, and 12 weeks: p = 0.354, < 0.001 and 0.002, respectively, in the HA group; p = 0.040, < 0.001 and < 0.001, respectively, in the CsN group). However, no significant change was observed according to the DEQS at any time point (Table 3).

Table 3 Comparison of changes in SANDE and DEQS (ocular symptom and impact on daily life) between the hyaluronic acid and cyclosporine nanoemulsion groups

	HA 0.15%
(n = 15)	CsN 0.05%
(n = 15)	P value	
SANDE				
Base line	70.13 ± 24.96	72.70 ± 20.43	0.761	
Week 4	63.67 ± 27.67	63.65 ± 17.81	0.999	
Baseline vs. Week 4	-0.42 ± 15.09

(p = 0.354)

	-8.95 ± 14.66

(p = 0.040)*

	0.425	
Week 8	56.75 ± 23.20	56.54 ± 18.99	0.979	
Baseline vs. Week 8	-13.38 ± 12.45

(p < 0.001)*

	-16.06 ± 11.17

(p < 0.001)*

	0.548	
Week 12	53.09 ± 28.09	47.13 ± 24.89	0.543	
Baseline vs. Week 12	-17.04 ± 16.96

(p = 0.002)*

	-25.57 ± 20.37

(p < 0.001)*

	0.224	
DEQS

(Ocular symptom)

				
Base line	41.67 ± 23.68	47.12 ± 12.54	0.459	
Week 4	40.77 ± 27.45	48.72 ± 16.35	0.375	
Baseline vs. Week 4	-0.89 ± 10.61

(p = 0.758)

	-1.74 ± 15.84

(p = 0.711)

	0.873	
Week 8	42.31 ± 24.64	45.24 ± 17.28	0.722	
Baseline vs. Week 8	-0.32 ± 18.28

(p = 0.951)

	-3.53 ± 12.60

(p = 0.333)

	0.607	
Week 12	39.88 ± 24.05	39.88 ± 20.33	1.000	
Baseline vs. Week 12	-1.79 ± 13.04

(p = 0.617)

	-9.62 ± 20.08

(p = 0.110)

	0.238	
DEQS

(Impact on Daily life)

				
Base line	39.68 ± 27.49	38.66 ± 10.89	0.899	
Week 4	38.09 ± 26.99	42.66 ± 21.53	0.625	
Baseline vs. Week 4	-1.594.36

(p = 0.686)

	4.17 ± 19.15

(p = 0.467)

	0.390	
Week 8	42.09 ± 25.96	33.73 ± 15.97	0.319	
Baseline vs. Week 8	4.27 ± 18.13

(p = 0.412)

	-4.40 ± 10.76

(p = 0.184)

	0.164	
Week 12	41.66 ± 27.64	38.10 ± 20.83	0.703	
Baseline vs. Week 12	1.98 ± 20.25

(p = 0.720)

	-1.16 ± 15.42

(p = 0.800)

	0.665	
* Statistically significant (p < 0.05).

HA = Hyaluronic acid 0.15%; CsN = Cyclosporine Nanoemulsion 0.05%; SANDE = Symptom Assessment in Dry Eye; DEQS = Dry Eye-related Quality of life Score Questionnaire.

Furthermore, there was no significant difference in ODAS1-7 within the groups at weeks 4, 8, and 12 compared with baseline and no significant differences between the two groups were observed. Additionally, no significant difference in ODAS8 was found at any time point; however, the onset time of ocular discomfort significantly increased in the CsN group at 12 weeks (p = 0.036; Table 4).

Table 4 Comparison of changes in ODAS (1–7) and ODAS8 (time the symptom started) between the hyaluronic acid and cyclosporine nanoemulsion groups

	HA 0.15%
(n = 15)	CsN 0.05%
(n = 15)	P value	
ODAS (1–7)				
Base line	31.67 ± 16.17	25.46 ± 15.59	0.313	
Week 4	31.80 ± 19.08	28.15 ± 18.71	0.607	
Baseline vs. Week 4	0.133 ± 8.87

(p = 0.954)

	2.69 ± 14.69

(p = 0.521)

	0.255	
Week 8	31.47 ± 16.29	25.92 ± 15.46	0.451	
Baseline vs. Week 8	-0.20 ± 9.19

(p = 0.934)

	-0.50 ± 11.74

(p = 0.885)

	0.524	
Week 12	32.13 ± 16.44	25.50 ± 16.04	0.282	
Baseline vs. Week 12	0.47 ± 9.26

(p = 0.848)

	-2.58 ± 11.02

(p = 0.434)

	0.442	
ODAS8 (minutes)				
Base line	51.43 ± 44.83	41.08 ± 32.64	0.502	
Week 4	43.08 ± 26.02	60.36 ± 81.54	0.513	
Baseline vs. Week 4	-10.00 ± 35.65

(p = 0.332)

	20.00 ± 59.81

(p = 0.318)

	0.148	
Week 8	52.69 ± 32.83	57.27 ± 55.69	0.805	
Baseline vs. Week 8	0.38 ± 42.60

(p = 0.975)

	13.00 ± 36.83

(p = 0.293)

	0.464	
Week 12	42.31 ± 20.06	82.08 ± 89.78	0.159	
Baseline vs. Week 12	-8.46 ± 43.51

(p = 0.497)

	44.50 ± 69.70

(p = 0.074)

	0.036*	
* Statistically significant (p < 0.05).

HA = Hyaluronic acid 0.15%; CsN = Cyclosporine Nanoemulsion 0.05%; ODAS = Ocular Discomfort Analog Scale.

Correlation between symptomatic questionnaires

Pearson’s correlation coefficient revealed a significant correlation between SANDE and DEQS scores (R = 0.672; p < 0.001; Fig. 2A), between SANDE and ODAS1-7 scores (R = 0.796; p < 0.001; Fig. 2B) and between DEQS and ODAS1-7 scores (R = 0.756; p < 0.001; Fig. 2C). However, there was no significant correlation between ODAS8 and SANDE or DEQS scores.

Fig. 2 Scatterplots showing the correlation between Symptom Assessment in Dry Eye (SANDE), Dry Eye-related Quality of life Score questionnaire (DEQS), and Ocular Discomfort Analog Scale (ODAS). (A) Pearson’s correlation coefficient analysis revealed a significant correlation between SANDE and DEQS scores (R = 0.672; p < 0.001) (B) Correlation between SANDE and ODAS1-7 scores (R = 0.796; p < 0.001) (C) Correlation between DEQS and ODAS1-7 scores (R = 0.756; p < 0.001)

Discussion

In this prospective, randomized, double-masked, and placebo-controlled study including a cohort of patients with mild-to-moderate dry eyes, treatment with 0.05% CsN rapidly improved the associated signs and symptoms, as well as the objective and subjective parameters. The ocular surface findings were significantly better in the CsN group than in the HA group across all follow-up periods. These results demonstrate the superiority of 0.05% CsN over 0.15% HA treatment for dry eye, consistent with the findings from previous studies [7, 10, 22].

Dry eye is induced by the aqueous deficiency or hyper-evaporative state of the tear film, resulting in hyperosmolarity [23]. Hyperosmolarity triggers mitogen-activated protein kinase or nuclear factor kappa beta that promote secretion of inflammatory cytokines, which damage epithelial cells and mucin-secreting goblet cells in the conjunctiva. The tear film then becomes unstable, increasing ocular surface damage and undesirable ocular symptoms [23]. The anti-inflammatory effects of cyclosporine A have been demonstrated through various mechanisms, including inhibition of T-cell activation and cytokine production, and reduction of the expression of epithelial cell apoptosis marker, thereby increasing conjunctival goblet cell density and decreasing squamous metaplasia [24–26]. Meanwhile, topical cyclosporine A used in the present study uses a self-nanoemulsifying drug delivery system, which has a larger surface area and improved homogeneity and stability compared to the conventional anionic oil-in-water emulsions. In an animal study using a murine model of dry eye, the anti-inflammatory effect was confirmed within 2 weeks when CsN was used, and corneal epithelium and conjunctival goblet cell protection were more efficiently achieved than conventional agent [6]. In a clinical study conducted on patients with Sjögren’s syndrome, CsN also showed faster improvement compared to conventional agent, suggesting that the induction time of the agent could be reduced by enhancing the physicochemical properties [22].

HA is a form of artificial tears that has been extensively used to treat dry eye disease for a long time. HA’s abundance of hydroxyl groups attracts water molecules, thickening and stabilizing the tear film, and its lubricating properties reduce mechanical trauma to the ocular surface [11, 13]. Additionally, HA contributes to re-epithelization of the corneal epithelium and prevents hyperosmolality of the tear film, thereby reducing ocular surface inflammation [11, 12]. Besides HA, mucin secretagogues such as diquafosol and rebamipide are increasingly used in South Korea to stabilize the tear film [27]. They stimulate mucin secretion from conjunctival goblet cells, increase the number of these cells, and improve mucosal epithelium [28]. However, achieving a sufficient anti-inflammatory effect using HA or mucin secretagogues alone is challenging. Topical cyclosporine is a single potent treatment tool targeting anti-inflammatory effects compared with other treatments for dry eye disease. Although comparisons between HA or mucin secretagogues and cyclosporine have been reported, data to prove a specific treatment’s superiority are insufficient, and follow-up studies are required.

Compared with baseline, TBUT and fluorescein staining scores at weeks 4, 8, and 12 significantly improved in the CsN group. Previous studies have shown that the effects of cyclosporine A typically begin after approximately 1 month, and the CsN group in this study has showed significant improvements in TBUT and fluorescein staining score from week 4, unlike the HA group, which is consistent with previous results [25, 29]. In Schirmer I test without anesthesia, a significant increase from baseline was observed at week 12 in the CsN group, and there was a statistically significant difference in the amount of change between the two groups at week 12. The Schirmer I test reflects improvement in sensory-stimulated reflex tearing associated with lacrimal gland tear production responses to ocular damage and is, therefore, appropriate for identifying long-term therapeutic effects [21]. A previous study demonstrated that eyes with detectable MMP-9 expression had significantly decreased tear production over time compared with those without detectable MMP-9 expression [30]. However, in the present study, all eyes remained negative for MMP-9 after 4 weeks of treatment. Tear production improved as shown in the Schirmer I test after 12 weeks.

Given the lack of association between the signs and symptoms of dry eye, various specific questionnaires have been developed. For example, some questionnaires evaluated the impact of dry eye on patient’s quality of life, whereas others focused on diagnosis, severity assessment, or screening [31]. In our study, both groups showed gradual, significant improvement in the SANDE score compared with baseline. The CsN group showed significant improvement in the SANDE score at 4 weeks, and both groups significantly improved at weeks 8 and 12. Although the Ocular Surface Disease Index (OSDI) is the most widely used questionnaire in dry eye clinical trials, it measures only the frequency, but not the severity, of dry eye symptoms, and shows poor correlation with the objective parameters in previous studies [19, 29]. However, SANDE as a short questionnaire based on VAS quickly reflected an improvement in the objective parameters, although it is not well refined. As a short and easily understandable questionnaire, SANDE has shown good reproducibility, repeatability, sensitivity, and specificity in assessing patients with symptoms of dry eye [19]. However, DEQS and ODAS did not show significant changes throughout the treatment period, which might reflect the differences in the characteristics of the questionnaires. DEQS was developed to assess the relationship between dry eye and quality of life in Japan [20]. Although it was based on the evaluation of quality of life and the multifaceted impact on patient daily life, the correlations between clinical parameters and questionnaire scores were low in a previous study [20].

Among the various questionnaires used in this study, SANDE, DEQS, and ODAS1-7 scores all showed significant correlations with each other, except for ODAS8 related to the onset time of dry eye symptoms. Although not developed for evaluating dry eye disease, the ocular discomfort analog scale during digital media usage correlated with other dry eye questionnaires and was related to decreased blinking rate and tear film instability [32]. The discrepancy between subjective symptoms and objective parameters in diagnosis and treatment assessment of dry eye can be explained by the natural variability of disease pathophysiology, symptom subjectivity, and the variability of cornea sensation [33–35]. According to the increasing importance of subjective and objective factors for dry eye treatment, various symptomatic questionnaires have been developed, while the patient-reported outcome guidance of FDA questionnaires recommends that they include objective indicators, subjective symptoms, and psychological feasibility. However, increasing the number of items in questionnaires may lead to a reduced response rate or recall bias due to patient input requirements [14]. Appropriate questionnaires with proper evaluating items should therefore be used according to their proper assessment; the impact of dry eye on quality of life, screening or diagnosis for dry eye disease, and severity assessment of dry eye disease should be evaluated.

Treatment-related adverse events following the use of 0.05% cyclosporine included burning eye, foreign body sensation, conjunctival hyperemia, visual disturbance, and eye pain [36]. In the present study, two participants (10.5%) discontinued CsN due to ocular discomfort after administration. Although the discontinuing rate in the present study was relatively high compared to the 2.2% in previous reports, further investigation of adverse effects was necessary considering the small number of participants in this study [37].

Our study has several limitations. First, the duration may not be sufficient to prove the long-term effects of cyclosporine A. Cyclosporine A eye drops may affect conjunctival inflammation by preventing recruitment of T cells, which may require between 3 and 6 months. However, previous studies have already revealed the long-term safety and efficacy outcomes of cyclosporin A treatment [38]. Second, commonly used questionnaires such as OSDI and Standard Patient Evaluation of Eye Dryness Questionnaire (SPEED) were not utilized for symptomatic evaluation. However, OSDI is copyrighted by Allergan Inc., which can limit its use for other industry concerns in clinical trials. SANDE scores correlated with those of the OSDI in patients with mild-to-moderate dry eyes [19]. Third, this study comprised relatively young patients (47.9-years-old in the HA group, 41.1-years-old in the CsN group), who were predominantly female, and exclusively Korean. To generalize these findings, data should be collected from patients of diverse age groups, sexes, and races.

In conclusion, both 0.05% CsN and 0.15% HA administration effectively improved the objective signs and subjective symptoms of dry eye. However, patients treated with 0.05% CsN improved more rapidly and effectively than patients treated with HA.

Acknowledgements

None.

Author contributions

Conceptualization, H.L., H.T., and J.Y.K.; Data curation, S.Y.M., H.S.C., H.T., and J.Y.K.; Formal analysis, S.Y.M., H.S.C., J.H.L., H.L., H.T., and J.Y.K.; Funding acquisition, J.Y.K.; Investigation, S.Y.M., H.S.C., J.H.L., H.L., H.T., and J.Y.K.; Software, S.Y.M., H.S.C., and J.Y.K.; Supervision, H.L., H.T., and J.Y.K.; Visualization, S.Y.M.; Writing – original draft, S.Y.M., H.S.C., and J.Y.K.; Writing – review & editing, S.Y.M., H.S.C., J.H.L., H.L., H.T., and J.Y.K. All authors have read and approved the final manuscript.

Funding

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (MEST) (NRF-2022R1F1A1073895), and by a grant (2024IP0069) from the Asan Institute for Life Sciences, Seoul, Korea.

Data availability

The dataset used during current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This study was conducted according to the ethical guidelines outlined in the Declaration of Helsinki and the Good Clinical Practice Guidelines. Written informed consent was obtained from all patients before the start of the study, and power analysis was performed to justify the number of enrolled patients. The study protocol and informed consents were reviewed and approved by the institutional review board of Asan Medical Center at the University of Ulsan in Seoul (Approval number: 2019 − 0884).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Abbreviations

CsN Cyclosporine nanoemulsion

TBUT Tear film break-up time

MMP-9 Matrix metalloproteinase 9

SANDE Symptom Assessment in Dry Eye

DEQS Dry Eye-Related Quality-of-Life Score

ODAS Ocular Discomfort Analog Scale

VAS Visual analog scale

QOLS Quality-of-Life Scale

OSDI Ocular Surface Disease Index

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Su Young Moon and Ho Seok Chung contributed equally to this work.
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References

1. Craig JP Nichols KK Akpek EK Caffery B Dua HS Joo C-K Liu Z Nelson JD Nichols JJ Tsubota K TFOS DEWS II definition and classification report Ocul Surf 2017 15 3 276 83 10.1016/j.jtos.2017.05.008 28736335
Craig JP, Nichols KK, Akpek EK, Caffery B, Dua HS, Joo C-K, Liu Z, Nelson JD, Nichols JJ, Tsubota K, et al. TFOS DEWS II definition and classification report. Ocul Surf. 2017;15(3):276–83.28736335 10.1016/j.jtos.2017.05.008
2. Pflugfelder SC De Paiva CS Villarreal AL Stern ME Effects of sequential artificial tear and cyclosporine emulsion therapy on conjunctival goblet cell density and transforming growth factor-beta2 production Cornea 2008 27 1 64 9 10.1097/ICO.0b013e318158f6dc 18245969
Pflugfelder SC, De Paiva CS, Villarreal AL, Stern ME. Effects of sequential artificial tear and cyclosporine emulsion therapy on conjunctival goblet cell density and transforming growth factor-beta2 production. Cornea. 2008;27(1):64–9.18245969 10.1097/ICO.0b013e318158f6dc
3. Kunert KS Tisdale AS Gipson IK Goblet cell numbers and epithelial proliferation in the conjunctiva of patients with dry eye syndrome treated with cyclosporine Arch Ophthalmol 2002 120 3 330 7 10.1001/archopht.120.3.330 11879137
Kunert KS, Tisdale AS, Gipson IK. Goblet cell numbers and epithelial proliferation in the conjunctiva of patients with dry eye syndrome treated with cyclosporine. Arch Ophthalmol. 2002;120(3):330–7.11879137 10.1001/archopht.120.3.330
4. Tsubota K Fujita H Tadano K Takeuchi T Murakami T Saito I Hayashi Y Improvement of lacrimal function by topical application of CyA in murine models of Sjögren’s syndrome Invest Ophthalmol Vis Sci 2001 42 1 101 10 11133854
Tsubota K, Fujita H, Tadano K, Takeuchi T, Murakami T, Saito I, Hayashi Y. Improvement of lacrimal function by topical application of CyA in murine models of Sjögren’s syndrome. Invest Ophthalmol Vis Sci. 2001;42(1):101–10.11133854
5. Moore CP McHugh JB Thorne JG Phillips TE Effect of cyclosporine on conjunctival mucin in a canine keratoconjunctivitis sicca model Invest Ophthalmol Vis Sci 2001 42 3 653 9 11222523
Moore CP, McHugh JB, Thorne JG, Phillips TE. Effect of cyclosporine on conjunctival mucin in a canine keratoconjunctivitis sicca model. Invest Ophthalmol Vis Sci. 2001;42(3):653–9.11222523
6. Bang SP Yeon CY Adhikari N Neupane S Kim H Lee DC Son MJ Lee HG Kim JY Jun JH Cyclosporine A eyedrops with self-nanoemulsifying drug delivery systems have improved physicochemical properties and efficacy against dry eye disease in a murine dry eye model PLoS ONE 2019 14 11 e0224805 10.1371/journal.pone.0224805 31738791
Bang SP, Yeon CY, Adhikari N, Neupane S, Kim H, Lee DC, Son MJ, Lee HG, Kim JY, Jun JH. Cyclosporine A eyedrops with self-nanoemulsifying drug delivery systems have improved physicochemical properties and efficacy against dry eye disease in a murine dry eye model. PLoS ONE. 2019;14(11):e0224805.31738791 10.1371/journal.pone.0224805
7. Kim HS Kim TI Kim JH Yoon KC Hyon JY Shin KU Choi CY Evaluation of clinical efficacy and safety of a Novel Cyclosporin A Nanoemulsion in the treatment of Dry Eye Syndrome J Ocul Pharmacol Ther 2017 33 7 530 8 10.1089/jop.2016.0164 28759302
Kim HS, Kim TI, Kim JH, Yoon KC, Hyon JY, Shin KU, Choi CY. Evaluation of clinical efficacy and safety of a Novel Cyclosporin A Nanoemulsion in the treatment of Dry Eye Syndrome. J Ocul Pharmacol Ther. 2017;33(7):530–8.28759302 10.1089/jop.2016.0164
8. Chen M Gong L Sun X Xie H Zhang Y Zou L Qu J Li Y He J A comparison of cyclosporine 0.05% ophthalmic emulsion versus vehicle in Chinese patients with moderate to severe dry eye disease: an eight-week, multicenter, randomized, double-blind, parallel-group trial J Ocul Pharmacol Ther 2010 26 4 361 6 10.1089/jop.2009.0145 20698799
Chen M, Gong L, Sun X, Xie H, Zhang Y, Zou L, Qu J, Li Y, He J. A comparison of cyclosporine 0.05% ophthalmic emulsion versus vehicle in Chinese patients with moderate to severe dry eye disease: an eight-week, multicenter, randomized, double-blind, parallel-group trial. J Ocul Pharmacol Ther. 2010;26(4):361–6.20698799 10.1089/jop.2009.0145
9. Petrochenko PE Pavurala N Wu Y Yee Wong S Parhiz H Chen K Patil SM Qu H Buoniconti P Muhammad A Analytical considerations for measuring the globule size distribution of cyclosporine ophthalmic emulsions Int J Pharm 2018 550 1–2 229 39 10.1016/j.ijpharm.2018.08.030 30125649
Petrochenko PE, Pavurala N, Wu Y, Yee Wong S, Parhiz H, Chen K, Patil SM, Qu H, Buoniconti P, Muhammad A, et al. Analytical considerations for measuring the globule size distribution of cyclosporine ophthalmic emulsions. Int J Pharm. 2018;550(1–2):229–39.30125649 10.1016/j.ijpharm.2018.08.030
10. Park CH Kim MK Kim EC Kim JY Kim TI Kim HK Song JS Yoon KC Lee DH Lee HK Efficacy of Topical Cyclosporine Nanoemulsion 0.05% compared with topical cyclosporine Emulsion 0.05% and diquafosol 3% in Dry Eye Korean J Ophthalmol 2019 33 4 343 52 10.3341/kjo.2018.0116 31389210
Park CH, Kim MK, Kim EC, Kim JY, Kim TI, Kim HK, Song JS, Yoon KC, Lee DH, Lee HK, et al. Efficacy of Topical Cyclosporine Nanoemulsion 0.05% compared with topical cyclosporine Emulsion 0.05% and diquafosol 3% in Dry Eye. Korean J Ophthalmol. 2019;33(4):343–52.31389210 10.3341/kjo.2018.0116
11. Hynnekleiv L Magno M Vernhardsdottir RR Moschowits E Tønseth KA Dartt DA Vehof J Utheim TP Hyaluronic acid in the treatment of dry eye disease Acta Ophthalmol 2022 100 8 844 60 10.1111/aos.15159 35514082
Hynnekleiv L, Magno M, Vernhardsdottir RR, Moschowits E, Tønseth KA, Dartt DA, Vehof J, Utheim TP. Hyaluronic acid in the treatment of dry eye disease. Acta Ophthalmol. 2022;100(8):844–60.35514082 10.1111/aos.15159
12. Yang YJ, Lee WY, Kim YJ, Hong YP. A Meta-analysis of the efficacy of Hyaluronic Acid Eye drops for the treatment of Dry Eye Syndrome. Int J Environ Res Public Health 2021, 18(5).
13. Johnson ME Murphy PJ Boulton M Effectiveness of sodium hyaluronate eyedrops in the treatment of dry eye Graefes Arch Clin Exp Ophthalmol 2006 244 1 109 12 10.1007/s00417-005-0028-1 15983814
Johnson ME, Murphy PJ, Boulton M. Effectiveness of sodium hyaluronate eyedrops in the treatment of dry eye. Graefes Arch Clin Exp Ophthalmol. 2006;244(1):109–12.15983814 10.1007/s00417-005-0028-1
14. Okumura Y, Inomata T, Iwata N, Sung J, Fujimoto K, Fujio K, Midorikawa-Inomata A, Miura M, Akasaki Y, Murakami A. A review of Dry Eye questionnaires: measuring patient-reported outcomes and Health-Related Quality of Life. Diagnostics (Basel) 2020, 10(8).
15. Hyon JY Kim HM Lee D Chung ES Song JS Choi CY Lee J Korean corneal Disease Study G: Korean guidelines for the diagnosis and management of dry eye: development and validation of clinical efficacy Korean J Ophthalmol 2014 28 3 197 206 10.3341/kjo.2014.28.3.197 24882952
Hyon JY, Kim HM, Lee D, Chung ES, Song JS, Choi CY, Lee J. Korean corneal Disease Study G: Korean guidelines for the diagnosis and management of dry eye: development and validation of clinical efficacy. Korean J Ophthalmol. 2014;28(3):197–206.24882952 10.3341/kjo.2014.28.3.197
16. Sambursky R Presence or absence of ocular surface inflammation directs clinical and therapeutic management of dry eye Clin Ophthalmol 2016 10 2337 43 10.2147/OPTH.S121256 27920494
Sambursky R. Presence or absence of ocular surface inflammation directs clinical and therapeutic management of dry eye. Clin Ophthalmol. 2016;10:2337–43.27920494 10.2147/OPTH.S121256
17. Lanza NL Valenzuela F Perez VL Galor A The Matrix metalloproteinase 9 point-of-care test in Dry Eye Ocul Surf 2016 14 2 189 95 10.1016/j.jtos.2015.10.004 26850527
Lanza NL, Valenzuela F, Perez VL, Galor A. The Matrix metalloproteinase 9 point-of-care test in Dry Eye. Ocul Surf. 2016;14(2):189–95.26850527 10.1016/j.jtos.2015.10.004
18. Messmer EM von Lindenfels V Garbe A Kampik A Matrix Metalloproteinase 9 testing in Dry Eye Disease using a commercially available point-of-care immunoassay Ophthalmology 2016 123 11 2300 8 10.1016/j.ophtha.2016.07.028 27665213
Messmer EM, von Lindenfels V, Garbe A, Kampik A. Matrix Metalloproteinase 9 testing in Dry Eye Disease using a commercially available point-of-care immunoassay. Ophthalmology. 2016;123(11):2300–8.27665213 10.1016/j.ophtha.2016.07.028
19. Amparo F Schaumberg DA Dana R Comparison of two questionnaires for Dry Eye Symptom Assessment: the ocular surface Disease Index and the Symptom Assessment in Dry Eye Ophthalmology 2015 122 7 1498 503 10.1016/j.ophtha.2015.02.037 25863420
Amparo F, Schaumberg DA, Dana R. Comparison of two questionnaires for Dry Eye Symptom Assessment: the ocular surface Disease Index and the Symptom Assessment in Dry Eye. Ophthalmology. 2015;122(7):1498–503.25863420 10.1016/j.ophtha.2015.02.037
20. Sakane Y Yamaguchi M Yokoi N Uchino M Dogru M Oishi T Ohashi Y Ohashi Y Development and validation of the Dry Eye-Related Quality-of-life score questionnaire JAMA Ophthalmol 2013 131 10 1331 8 10.1001/jamaophthalmol.2013.4503 23949096
Sakane Y, Yamaguchi M, Yokoi N, Uchino M, Dogru M, Oishi T, Ohashi Y, Ohashi Y. Development and validation of the Dry Eye-Related Quality-of-life score questionnaire. JAMA Ophthalmol. 2013;131(10):1331–8.23949096 10.1001/jamaophthalmol.2013.4503
21. Kim H Kim HT Shin DH Lim HT Choi CY Cho WJ Kim JY Kim CY Tchah H Reduction of Blue Light Emission in internet-protocol television and its effect on ocular fatigue J Korean Ophthalmol Soc 2018 59 3 230 7 10.3341/jkos.2018.59.3.230
Kim H, Kim HT, Shin DH, Lim HT, Choi CY, Cho WJ, Kim JY, Kim CY, Tchah H. Reduction of Blue Light Emission in internet-protocol television and its effect on ocular fatigue. J Korean Ophthalmol Soc. 2018;59(3):230–7.10.3341/jkos.2018.59.3.230
22. Kang MJ Kim YH Chou M Hwang J Cheon EJ Lee HJ Chung SH Evaluation of the efficacy and safety of a novel 0.05% cyclosporin A topical nanoemulsion in primary Sjögren’s Syndrome Dry Eye Ocul Immunol Inflamm 2020 28 3 370 8 10.1080/09273948.2019.1587470 30986119
Kang MJ, Kim YH, Chou M, Hwang J, Cheon EJ, Lee HJ, Chung SH. Evaluation of the efficacy and safety of a novel 0.05% cyclosporin A topical nanoemulsion in primary Sjögren’s Syndrome Dry Eye. Ocul Immunol Inflamm. 2020;28(3):370–8.30986119 10.1080/09273948.2019.1587470
23. Bron AJ de Paiva CS Chauhan SK Bonini S Gabison EE Jain S Knop E Markoulli M Ogawa Y Perez V TFOS DEWS II pathophysiology report Ocul Surf 2017 15 3 438 510 10.1016/j.jtos.2017.05.011 28736340
Bron AJ, de Paiva CS, Chauhan SK, Bonini S, Gabison EE, Jain S, Knop E, Markoulli M, Ogawa Y, Perez V, et al. TFOS DEWS II pathophysiology report. Ocul Surf. 2017;15(3):438–510.28736340 10.1016/j.jtos.2017.05.011
24. Daull P Feraille L Barabino S Cimbolini N Antonelli S Mauro V Garrigue JS Efficacy of a new topical cationic emulsion of cyclosporine A on dry eye clinical signs in an experimental mouse model of dry eye Exp Eye Res 2016 153 159 64 10.1016/j.exer.2016.10.016 27777121
Daull P, Feraille L, Barabino S, Cimbolini N, Antonelli S, Mauro V, Garrigue JS. Efficacy of a new topical cationic emulsion of cyclosporine A on dry eye clinical signs in an experimental mouse model of dry eye. Exp Eye Res. 2016;153:159–64.27777121 10.1016/j.exer.2016.10.016
25. Wan KH Chen LJ Young AL Efficacy and safety of topical 0.05% Cyclosporine Eye drops in the treatment of Dry Eye Syndrome: a systematic review and Meta-analysis Ocul Surf 2015 13 3 213 25 10.1016/j.jtos.2014.12.006 26045239
Wan KH, Chen LJ, Young AL. Efficacy and safety of topical 0.05% Cyclosporine Eye drops in the treatment of Dry Eye Syndrome: a systematic review and Meta-analysis. Ocul Surf. 2015;13(3):213–25.26045239 10.1016/j.jtos.2014.12.006
26. Gao J Sana R Calder V Calonge M Lee W Wheeler LA Stern ME Mitochondrial permeability transition pore in inflammatory apoptosis of human conjunctival epithelial cells and T cells: effect of cyclosporin A Invest Ophthalmol Vis Sci 2013 54 7 4717 33 10.1167/iovs.13-11681 23778874
Gao J, Sana R, Calder V, Calonge M, Lee W, Wheeler LA, Stern ME. Mitochondrial permeability transition pore in inflammatory apoptosis of human conjunctival epithelial cells and T cells: effect of cyclosporin A. Invest Ophthalmol Vis Sci. 2013;54(7):4717–33.23778874 10.1167/iovs.13-11681
27. Jin Y Seo KY Kim SW Comparing two mucin secretagogues for the treatment of dry eye disease: a prospective randomized crossover trial Sci Rep 2024 14 1 13306 10.1038/s41598-024-63784-4 38858411
Jin Y, Seo KY, Kim SW. Comparing two mucin secretagogues for the treatment of dry eye disease: a prospective randomized crossover trial. Sci Rep. 2024;14(1):13306.38858411 10.1038/s41598-024-63784-4
28. Shimazaki J Seika D Saga M Fukagawa K Sakata M Iwasaki M Okano T A prospective, randomized trial of two mucin secretogogues for the treatment of Dry Eye Syndrome in Office workers Sci Rep 2017 7 1 15210 10.1038/s41598-017-13121-9 29123104
Shimazaki J, Seika D, Saga M, Fukagawa K, Sakata M, Iwasaki M, Okano T. A prospective, randomized trial of two mucin secretogogues for the treatment of Dry Eye Syndrome in Office workers. Sci Rep. 2017;7(1):15210.29123104 10.1038/s41598-017-13121-9
29. Chen D Zhang S Bian A Hong J Deng Y Zhang M Chen W Shao Y Zhao J Efficacy and safety of 0.05% cyclosporine ophthalmic emulsion in treatment of Chinese patients with moderate to severe dry eye disease: a 12-week, multicenter, randomized, double-masked, placebo-controlled phase III clinical study Med (Baltim) 2019 98 31 e16710 10.1097/MD.0000000000016710
Chen D, Zhang S, Bian A, Hong J, Deng Y, Zhang M, Chen W, Shao Y, Zhao J. Efficacy and safety of 0.05% cyclosporine ophthalmic emulsion in treatment of Chinese patients with moderate to severe dry eye disease: a 12-week, multicenter, randomized, double-masked, placebo-controlled phase III clinical study. Med (Baltim). 2019;98(31):e16710.10.1097/MD.0000000000016710
30. Soifer M Mousa HM Stinnett SS Galor A Perez VL Matrix metalloproteinase 9 positivity predicts long term decreased tear production Ocul Surf 2021 19 270 4 10.1016/j.jtos.2020.10.003 33098983
Soifer M, Mousa HM, Stinnett SS, Galor A, Perez VL. Matrix metalloproteinase 9 positivity predicts long term decreased tear production. Ocul Surf. 2021;19:270–4.33098983 10.1016/j.jtos.2020.10.003
31. Shiraishi A Sakane Y Assessment of Dry Eye symptoms: current trends and issues of Dry Eye questionnaires in Japan Invest Ophthalmol Vis Sci 2018 59 14 Des23 8 10.1167/iovs.18-24570 30481802
Shiraishi A, Sakane Y. Assessment of Dry Eye symptoms: current trends and issues of Dry Eye questionnaires in Japan. Invest Ophthalmol Vis Sci. 2018;59(14):Des23–8.30481802 10.1167/iovs.18-24570
32. Argilés M Cardona G Pérez-Cabré E Rodríguez M Blink rate and incomplete blinks in six different controlled Hard-Copy and Electronic Reading conditions Invest Ophthalmol Vis Sci 2015 56 11 6679 85 10.1167/iovs.15-16967 26517404
Argilés M, Cardona G, Pérez-Cabré E, Rodríguez M. Blink rate and incomplete blinks in six different controlled Hard-Copy and Electronic Reading conditions. Invest Ophthalmol Vis Sci. 2015;56(11):6679–85.26517404 10.1167/iovs.15-16967
33. Ong ES Felix ER Levitt RC Feuer WJ Sarantopoulos CD Galor A Epidemiology of discordance between symptoms and signs of dry eye Br J Ophthalmol 2018 102 5 674 9 10.1136/bjophthalmol-2017-310633 28821553
Ong ES, Felix ER, Levitt RC, Feuer WJ, Sarantopoulos CD, Galor A. Epidemiology of discordance between symptoms and signs of dry eye. Br J Ophthalmol. 2018;102(5):674–9.28821553 10.1136/bjophthalmol-2017-310633
34. Bartlett JD Keith MS Sudharshan L Snedecor SJ Associations between signs and symptoms of dry eye disease: a systematic review Clin Ophthalmol 2015 9 1719 30 10.2147/OPTH.S89700 26396495
Bartlett JD, Keith MS, Sudharshan L, Snedecor SJ. Associations between signs and symptoms of dry eye disease: a systematic review. Clin Ophthalmol. 2015;9:1719–30.26396495 10.2147/OPTH.S89700
35. Nichols KK Nichols JJ Mitchell GL The lack of association between signs and symptoms in patients with dry eye disease Cornea 2004 23 8 762 70 10.1097/01.ico.0000133997.07144.9e 15502475
Nichols KK, Nichols JJ, Mitchell GL. The lack of association between signs and symptoms in patients with dry eye disease. Cornea. 2004;23(8):762–70.15502475 10.1097/01.ico.0000133997.07144.9e
36. Kymionis GD Bouzoukis DI Diakonis VF Siganos C Treatment of chronic dry eye: focus on cyclosporine Clin Ophthalmol 2008 2 4 829 36 10.2147/OPTH.S1409 19668437
Kymionis GD, Bouzoukis DI, Diakonis VF, Siganos C. Treatment of chronic dry eye: focus on cyclosporine. Clin Ophthalmol. 2008;2(4):829–36.19668437 10.2147/OPTH.S1409
37. Sall K Stevenson OD Mundorf TK Reis BL Two multicenter, randomized studies of the efficacy and safety of cyclosporine ophthalmic emulsion in moderate to severe dry eye disease. CsA Phase 3 Study Group Ophthalmology 2000 107 4 631 9 10.1016/S0161-6420(99)00176-1 10768324
Sall K, Stevenson OD, Mundorf TK, Reis BL. Two multicenter, randomized studies of the efficacy and safety of cyclosporine ophthalmic emulsion in moderate to severe dry eye disease. CsA Phase 3 Study Group. Ophthalmology. 2000;107(4):631–9.10768324 10.1016/S0161-6420(99)00176-1
38. Baudouin C Figueiredo FC Messmer EM Ismail D Amrane M Garrigue JS Bonini S Leonardi A A randomized study of the efficacy and safety of 0.1% cyclosporine a cationic emulsion in treatment of moderate to severe dry eye Eur J Ophthalmol 2017 27 5 520 30 10.5301/ejo.5000952 28362054
Baudouin C, Figueiredo FC, Messmer EM, Ismail D, Amrane M, Garrigue JS, Bonini S, Leonardi A. A randomized study of the efficacy and safety of 0.1% cyclosporine a cationic emulsion in treatment of moderate to severe dry eye. Eur J Ophthalmol. 2017;27(5):520–30.28362054 10.5301/ejo.5000952
