Comparative evaluation of aqueous solution and oil emulsion formulations of 0.05% cyclosporine eye drops in dry eye disease – A randomized clinical trial

Abstract

Purpose:

To compare the clinical response of patients with moderate-to-severe dry eye disease to treatment with 0.05% cyclosporine eye drops as an aqueous solution or oil emulsion.

Study Design:

Prospective randomized clinical trial.

Methods:

An institutional study where 88 patients with moderate-to-severe dry eye was enrolled after written informed consent and randomized to receive either aqueous solution (Group 1) or oil emulsion (Group 2) 0.05% cyclosporine eye drops in twice daily dosing in addition to lubricant eyedrop 0.5% carboxymethylcellulose six times/day in both eyes. Comprehensive eye examination and baseline parameters were recorded, and clinical assessment was repeated at 4, 8, and 12 weeks. Parameters evaluated included ocular surface disease index score (OSDI), Schirmer test, tear break-up time (TBUT), corneal fluorescein staining – National Eye Institute (NEI) scoring, lipid layer thickness (LLT), tear meniscus height (TMH), non-invasive tear break-up time (NIBUT), percentage loss of meibomian glands, and impression cytology (number of goblet cells/hpf).

Results:

The mean age was 39 ± 15.6 years and 42 ± 17.7 years, and the M:F ratio was 26:19 and 20:24 in Groups 1 and 2, respectively. Both the groups showed comparable values at baseline. After treatment, there was statistically significant improvement over baseline values in both groups at 4, 8, and 12 weeks. At 12 weeks for the following parameters, there was no significant difference between the groups, though there was an improvement over baseline in Groups 1 and 2, respectively, as follows: OSDI score – 30.89, 33.28 (P < 0.001), Schirmer test – 5 mm, 4 mm (P < 0.001), TBUT – 2.65 sec, 3.07 sec (P < 0.001), NEI score – 2, 2 (P < 0.001) and the number of goblet cells/hpf – 1.5,9 (P = 0016, P = 0.001). A higher number of patients, by a value of 9, in Group 2 showed an increase in the number of goblet cells/hpf. The NIBUT value showed statistically significant improvement in Group 2 compared to Group 1 (P = 0.011). Group 2 also showed statistically significant improvement in TMH by the 8^th week (P = 0.015) and in LLT by the 12^th week (P < 0.001). Group 1 comparatively showed earlier improvement in LLT by the 4^th week (P = 0.027).

Conclusion:

Both aqueous solution and oil emulsion 0.05% cyclosporine formulations appear to be equally effective in the management of dry eye disease with a comparatively better response with oil emulsion formulations.

Dry eye disease (DED), alternatively termed keratoconjunctivitis sicca, stands as a prevalent ocular surface ailment impacting millions of individuals globally. The prevalence of DED among adults worldwide ranges from 5% to 50%.[1]

According to the DEWS 2 (Dry Eye Workshop 2) report of 2017 – “Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.”[2]

The main management modality for DED is the use of ocular lubricants. From numerous studies, we already know that tear hyperosmolarity plays a central mechanism in the pathophysiology of DED.[3] This in turn is said to damage the ocular surface by initiating inflammation (directly as well as indirectly). Thus, the primary focus for the management of DED lies in addressing the relentless inflammatory cycle. However, the use of topical steroids for a long period can be harmful because of the large number of adverse effects associated with it. Hence, the treatment of DED also entails the utilization of topical non-glucocorticoid immunomodulatory drugs like cyclosporine eyedrops which target the T cells and produce anti-inflammatory action by inhibiting the nuclear factor κB (NFκB) activation and also by inhibiting calcineurin thereby blocking the release of interleukin 2.

Different concentrations of topical cyclosporine are available in the market. For this study, we specifically selected a concentration of 0.05% of cyclosporine eye drops. This choice was based on previous research by Stevenson et al.,[4] who concluded that increasing the concentration of cyclosporine did not provide any additional therapeutic benefits. They suggested that future clinical studies should instead focus on formulations containing cyclosporine at concentrations of 0.05% and 0.1%. Notably, in their study, cyclosporine 0.05% consistently produced the most significant improvements in patient symptoms, such as a reduction in sandy or gritty feeling and ocular dryness.

There are two main topical formulations of 0.05% cyclosporine available for the treatment of DED – aqueous solution and oil emulsion. But both these formulations possess their sets of merits and drawbacks. Cyclosporine is a lipophilic molecule and hence better formulated as oil emulsion preparations. The oil droplet encasing cyclosporine may merge with the tear film lipid layer, act as a drug reservoir, and allow a sustained release of cyclosporine.[5] However, studies indicate that oil emulsion cyclosporine formulations have poor bioavailability due to the greater attraction of the molecule to the lipophilic vehicle than the tissues.[6] Aqueous solutions, on the other hand, use micellar technology which facilitates drug penetration and thereby improves the bioavailability of cyclosporine.

So, the main aim of this study is to compare the clinical outcome of both these formulations of 0.05% cyclosporine eye drops in the treatment of moderate-to-severe DED.

Methods

This prospective, randomized clinical trial, with two parallel arms, was started after obtaining ethical clearance from the Institute Ethics Committee and was conducted by the Declaration of Helsinki. CTRI registration was also done before the study. All the participants were provided with a participant information sheet and were included in the study after obtaining written informed consent from the patients.

Patients who fulfilled the selection criteria were recruited for the study. The inclusion criteria included the following – Patients in the age group between 18 and 65 years with moderate-to-severe DED not resolving by treatment with lubricant eyedrops, one or more dry eye symptoms (dryness, burning, photophobia, tearing, and foreign body sensation), TBUT ≤10 seconds, National Eye Institute (NEI) staining score of >3 out of 15, Schirmer test ≤ 10 mm/5 min, and OSDI score >23. The exclusion criteria were as follows – Any patient who disagreed to participate in the trial, any history of the active stage of any other ocular disease, history of ocular trauma, blepharitis, infection, or inflammation not associated with DED during the 3 months preceding the screening visit, any ocular surgery within the last 3 months, history of hypersensitivity or any contraindications, patients taking any medication, topically or by any other route, which could interfere with the study’s results, contact lens users, legally disqualified or mentally disabled patients who cannot sign an informed consent and patients who cannot comply with medical appointments or with all the protocol requirements.

A total of 88 patients, both eyes included in the study, were enrolled and randomized into two groups with the help of a computer-generated randomization table. The sample size was determined by considering the power of the study to be 90%. Group 1 patients received aqueous solution 0.05% cyclosporine eye drops – cyclomune eyedrop 0.05% by Sun Pharmaceutical Industries Ltd (88 eyes), and Group 2 patients received oil emulsion 0.05% cyclosporine eye drops – Restasis eyedrops 0.05% by Allergan (88 eyes). All patients were prescribed cyclosporine eyedrops in twice daily dosing along with a lubricant eyedrop carboxymethylcellulose 0.5% eyedrops six times/day. This was an institutional study, and all the patients were followed up for 3 months. The patients enrolled underwent comprehensive eye examination, and the following parameters were assessed at baseline, 4, 8, and 12 weeks – Schirmer test, tear break-up time (TBUT), corneal fluorescein staining (using NEI scoring), ocular surface disease index (OSDI) score, impression cytology (the number of goblet cells/high power field), lipid layer thickness (LLT), tear meniscus height (TMH), non-invasive tear break-up time (NIBUT), and percentage loss of meibomian glands (Meibography of both the upper lid and lower lid). LLT, TMH, NIBUT, and percentage loss of meibomian glands were evaluated using the ocular surface analyzer (OSA) device.

All the data were compiled in an Excel sheet, and the statistical analysis was performed by SPSS 23.0 version. Categorical variables were described by taking percentages (analyzed using the Chi-square test). Continuous variables were described as mean and variation of each observation from the mean value (standard deviation) represented as mean ± SD (analyzed using independent t-test) – if they followed a normal distribution and were described as median (IQR) – if they followed a non-normal distribution (analyzed using Mann Whitney U test). Continuous paired data were analyzed using paired t-test (for normal distribution) and Wilcoxon signed rank test (for non-normal distribution). Variables with P value < 0.05 were considered statistically significant.

Results

The mean age of the patients in Group 1 was 39 ± 15.6, and in Group 2, it was 42 ± 17.7. There was no statistically significant difference between the two groups (P = 0.546). The M: F ratio was 26:19 and 20:24 in Groups 1 and 2, respectively. The gender distribution was comparable among the two groups (P = 0.245).

All the clinical parameters are comparable at baseline in both groups as shown in Table 1 (P > 0.05).

Table 1.

Baseline parameters of both the groups (P>0.05)

Study parameters	Group 1 Aqueous solution Median (IQR)	Group 2 Oil emulsion Median (IQR)	P (Mann Whitney U Test)
SCHIRMER TEST (mm)	7 (3-11)	8 (3-10.5)	0.787
CORNEAL STAINING SCORE (NEI)	4 (3-6)	4 (4-7)	0.072
LIPID LAYER THICKNESS (nm)	30 (30-55)	30 (20-42.5)	0.057
% OF MEIBOMIAN GLAND LOSS – UPPER LID	18 (11-22)	18 (11-23)	0.794
% OF MEIBOMIAN GLAND LOSS – LOWER LID	14 (10-19.5)	13 (8-22.5)	0.971
Study parameters	Group 1 aqueous solution MEAN±SD	Group 2 oil emulsion MEAN±SD	P (Unpaired t-test)
TBUT (sec)	5.25±1.88	4.85±1.69	0.141
TEAR MENISCUS HEIGHT (mm)	0.29±0.12	0.26±0.09	0.063
NIBUT (sec)	6.62±2.3	6.25±2.31	0.3
OSDI Score	56.41±11.15	57.05±9.47	0.684

Schirmer test

The baseline Schirmer test value between the two groups is comparable (P = 0.787). In Group 1, at baseline, the median Schirmer value was 7 (3–11) mm which improved to 8 (6–15) mm at 4 weeks, 10 (5–15) mm at 8 weeks, and 12 (6–20) mm at 12 weeks. Significant improvement was noted from baseline at 4, 8, and 12 weeks (P < 0.001).

Similarly in Group 2, the median Schirmer value at baseline was 8 (3–10.5) mm, which improved to 10 (6–12) mm at 4 weeks, 10 (7.5–14) mm at 8 weeks, and 12 (7–15) mm at 12 weeks. Significant improvement was noted from baseline at 4, 8, and 12 weeks (P < 0.001).

However, a statistically significant difference between the two groups was not noted at any point in the follow-up period (P > 0.05).

TBUT

Baseline TBUT values in both groups were comparable (P = 0.141). In Group 1, the baseline mean TBUT was 5.25 ± 1.88 sec, which improved to 6.21 ± 2.4 sec, 6.79 ± 2.22 sec, and 7.9 ± 2.59 sec at 4, 8, and 12 weeks, respectively. There was significant improvement from baseline at all points of follow-up (P < 0.001).

Similarly in Group 2, the mean TBUT at baseline was 4.85 ± 1.69 sec which improved to 6.05 ± 1.93 sec, 6.84 ± 1.93 sec, and 7.92 ± 2.62 sec at 4, 8, and 12 weeks, respectively. There was significant improvement from baseline at all points of follow-up (P < 0.001).

However, there was no significant difference between the two groups in follow-up visits (P > 0.05).

Corneal fluorescein staining (using the NEI grading system)

The baseline median corneal fluorescein staining scores are comparable in both groups (P = 0.072).

In Group 1, from the median baseline corneal fluorescein staining score of 4 (3–6), it has decreased significantly (P < 0.001) to 2 (2–5), 2 (2–4), and 2 (1–4) at 4, 8, and 12 weeks follow-up visits, respectively.

Also in Group 2, from the median baseline corneal fluorescein staining score of 4 (4–7), it has decreased significantly (P < 0.001) to 3 (2–6), 2 (2–5), and 2 (2–4) at 4, 8, and 12 weeks follow-up respectively.

However, there is no statistically significant difference between the two groups at any point in the follow-up visits.

OSDI score

The mean OSDI score in Group 1 was 56.41 ± 11.15 at baseline. It decreased at 4, 8, and 12 weeks to 40.93 ± 12.98, 30.49 ± 13.35, and 25.52 ± 10.82, respectively. The improvement is significant from baseline in all follow-up visits (P < 0.001).

In Group 2, the mean OSDI score at baseline was 57.05 ± 9.47, and there was a significant decrease from baseline at follow-up visits (P < 0.001) – 4, 8, and 12 weeks mean OSDI score is 40.43 ± 10.34, 28.58 ± 8.66 and 23.77 ± 9.47, respectively.

However, there is no statistically significant difference between the two groups at any point in the follow-up visits.

LLT

The median lipid layer thickness (in nanometres) in Group 1 was 30 (30–55) nm at baseline. By 4 weeks follow-up, significant early improvement in LLT was noted in Group 1 compared to Group 2 (P = 0.013). At 8- and 12-week follow-up visits, in Group 1, the median LLT showed statistically significant improvement from baseline to 30 (30–55) nm (P = 0.008) and 55 (30–55) nm (P = 0.001), respectively.

In Group 2, the baseline median LLT value is 30 (20–42.5) nm. At 12 weeks follow-up, it improved to 30 (30–55) nm, which was statistically significant from baseline (P < 0.001), and showed a significant improvement compared to Group 1 also (P = 0.035).

TMH

Baseline mean TMH values are comparable between the two groups (P = 0.063). On follow-up, in Group 1, the values initially showed a decrease in TMH at 4 weeks (mean TMH–0.27 ± 0.09 mm), but later on, improvement from baseline was noted by 12 weeks, which was not statistically significant (P = 0.585).

However, in Group 2, mean TMH showed statistically significant improvement from baseline (0.26 ± 0.09 mm) at the 2^nd follow-up visit, that is, at 8 weeks (0.29 ± 0.09 mm) – P = 0.015 (depicted in Fig. 1). At 12 weeks, the mean TMH was 0.33 ± 0.17 mm and P = 0.005 which indicated a statistically significant improvement from baseline.

Figure 1.

Double bar graph depicting TMH value comparison between the two groups from baseline and follow-up visits

NIBUT

The mean NIBUT at baseline was comparable between the two groups (P = 0.3). Group 1 showed statistically significant improvement from baseline at each follow-up visit (P < 0.001). At baseline, the mean NIBUT was 6.62 ± 2.3 sec, which improved to 7.35 ± 2.56 sec, 7.86 ± 2.39 sec, and 8.34 ± 2.31 sec at 4, 8, and 12-week visits, respectively.

In Group 2, the mean NIBUT value showed significant improvement from baseline (P < 0.05). From the baseline mean TBUT of 6.25 ± 2.31 sec, it improved to 7.25 ± 2.47 sec, 7.9 ± 2.26 sec, and 9.41 ± 2.6 sec at 4, 8, and 12 weeks, respectively.

In the third follow-up visit (at 12 weeks), there was a statistically significant improvement in mean NIBUT in Group 2 compared to Group 1 (P = 0.011). Fig. 2 is a line graph depicting the improvement of NIBUT in Group 2 over Group 1.

Figure 2.

Line graph depicting NIBUT value comparison between the two groups from baseline and follow-up visits

Percentage loss of meibomian glands

Percentage loss of meibomian glands did not show any significant change from baseline during the follow-up visits.

Impression cytology

In Group 1, the median number of goblet cells showed statistically significant improvement from the baseline value of 10 (6.25–13.5) to 11.5 (7.25–15.75) at 12 weeks post-treatment (P = 0.016).

Similarly in Group 2, the median number of goblet cells showed statistically significant improvement from the baseline value of 3.5 (1–6.5) to 12.5 (5.75–22) at 12-week post-treatment (P = 0.001).

However, in Group 1, in many patients, the number of goblet cells/high power field remained unchanged at baseline and post-treatment (12 weeks) – hence, the delta value is 0. However, the increase in the number of goblet cells/high power field in Group 2 was significant in a greater number of patients – the delta value is 7 (P = 0.0035). Fig. 3 denotes the box whiskers plot showing the significant improvement in goblet cells in both groups.

Figure 3.

Box whiskers plot depicting the number of goblet cells per high power field before and after treatment in both groups. The green boxes represent the change in the number of goblet cells present following treatment compared to the baseline in each group

Figs. 4a and 5a are the light microscopic images showing impression cytology specimens in Group 1 and 2 patients at baseline, showing only a few goblet cells per high power field. The black arrows indicate the goblet cells visible as bulbous cells with eccentric nuclei and pale staining cytoplasm. Figs. 4b and 5b are the light microscopic images showing impression cytology specimens of patients in Group 1 and 2 at 12 weeks, respectively, showing an increase in the number of goblet cells per high power field post treatment with 0.05% cyclosporine eye drops.

Figure 4.

Light microscopic slide image (H and E staining, 40X magnification) showing the impression cytology specimen of a patient in Group 1. (a) Pre-treatment, (b) post-treatment at 12 weeks

Figure 5.

Light microscopic slide image (H and E staining, 40X magnification) showing impression cytology specimen of a patient in Group 2. (a) pre-treatment, (b) post-treatment at 12 weeks. The black arrows indicate the goblet cells which are visible as bulbous cells with eccentric nuclei and pale staining cytoplasm

Discussion

The success of topical cyclosporine eyedrops in the management of DED has already been established by various studies. Specifically, an oil emulsion containing 0.05% cyclosporine A (Restasis; Allergan) received approval from the US Food and Drug Administration (FDA) in 2003 for the treatment of moderate-to-severe DED.

There exists a dearth of literature regarding comparative studies assessing the effectiveness of aqueous solution versus oil emulsion formulations of topical 0.05% cyclosporine in treating moderate-to-severe DED. While numerous studies have examined the use of cyclosporine eye drops for treating DED, the direct comparison between these two formulations has not been extensively investigated in clinical trials. So, this is the first study to compare the two formulations and assess the clinical outcome.

To date, only one study has been conducted that examines the use of aqueous-based cyclosporine eye drops (solution formulation) for the treatment of DED. Baiza-Durán et al.[7] conducted this study, which found that an aqueous solution of cyclosporine can have therapeutic effects on both symptoms and signs of DED. The study concluded that the use of a 0.05% cyclosporine aqueous solution is safe and results in statistically significant improvements in the Schirmer test (P = 0.031) and corneal fluorescein staining test (P = 0.016) by day 21. These findings align with our study, which also showed statistically significant improvements from baseline in the Schirmer test (P < 0.001) and corneal fluorescein staining (P < 0.001) after 4 weeks of follow-up in Group 1, that is, patients on treatment with aqueous solution 0.05% cyclosporine eye drops.

In contrast, numerous studies in the literature have investigated the use of oil-based cyclosporine formulations (emulsions) for the treatment of moderate-to-severe DED. In 2000, Stevenson et al.[4] examined the efficacy, safety, formulation tolerability, and optimal dose of the cyclosporine oil-in-water emulsion formulation. Their observations demonstrated that treatment with the topical cyclosporine oil emulsion formulation significantly improved the ocular manifestations of moderate-to-severe DED.

Furthermore, the study by Stevenson et al.[4] suggested that the formulation itself contributed to the therapeutic benefits observed in all treatment groups. One possible contributing factor to the beneficial effects of oil-based formulations may be the sustained presence of the vehicle on the ocular surface, which may last between 3 to 4 hours. This prolonged presence on the ocular surface could potentially reduce the evaporation of the limited volume of natural tears in individuals diagnosed with DED.

In a recent meta-analysis conducted by Gao et al.[8] in 2022, seven different formulations of cyclosporine eye drops were compared for the treatment of DED. Additionally, the study revealed that Restasis characterized as an oil emulsion formulation of 0.05% cyclosporine eye drop and demonstrated superior efficacy in diminishing the OSDI score. These findings are consistent with our study, which demonstrated a significant improvement in OSDI scores from baseline at 4, 8, and 12 weeks of follow-up visits (P < 0.001) in patients receiving oil-based 0.05% cyclosporine eye drops as a treatment for DED.

Conclusions

In our study, it has been found that both formulations have led to an improvement in DED parameters from baseline like – the Schirmer test, tear break-up time, corneal fluorescein staining, and OSDI score (P < 0.001).

However, the oil-based emulsions exhibited a better improvement in terms of NIBUT (P = 0.011), TMH (P = 0.05), and the increase in goblet cells at the end of the treatment period. This could point toward a better supremacy of oil-based formulations in the treatment of moderate-to-severe DED.

Given the relatively shorter duration of our study, which included a follow-up period of 3 months, it is important to acknowledge the need for longer-term investigations with a larger sample size. This would provide more robust evidence and enable us to draw more conclusive and reliable conclusions regarding the comparative effectiveness of these formulations.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.