Comparative Evaluation of 0.05% Cyclosporine A Plus Absorbable Punctal Plugs Versus 0.05% Cyclosporine A Monotherapy in Sjögren's Syndrome-Associated Dry Eye: A Paired-Eye Study

Participants meeting all eligibility criteria were enrolled and randomized to receive combined treatment (0.05% cyclosporine A plus absorbable punctal plug) in one eye and 0.05% cyclosporine A monotherapy in the contralateral eye. Eye allocation (left or right) was determined using block randomization with a fixed block size of two, implemented via an online randomization tool (www.sealedenvelope.com). The randomization sequence was generated in advance by an independent biostatistician who was not involved in patient care or data analysis.

Treatment allocation was concealed using sequentially numbered, opaque, sealed envelopes (SNOSE), which were prepared by an independent biostatistician not involved in patient care or outcome assessment. At the time of enrollment, a study coordinator opened the next envelope in sequence to determine which eye would receive the combined treatment. The contralateral eye automatically received cyclosporine A monotherapy.

To maintain masking, the ophthalmologists responsible for outcome assessment (including ocular surface staining, tear film measurements, and in vivo confocal microscopy) were blinded to the treatment allocation. Participants were informed that both eyes would receive active treatment and were not informed of the specific allocation. The investigators performing plug insertion and administering cyclosporine A were not involved in any clinical evaluations.

A total of 30 patients with Sjögren's syndrome-associated dry eye (SSDE) were planned for enrollment. The sample size calculation was based on a paired-eye design, in which each participant served as their own control. The calculation assumed a two-sided significance level of 0.05 (α = 0.05) and a statistical power of 95% (β = 0.05), aiming to detect a clinically meaningful difference in ocular surface parameters (e.g., tear breakup time or symptom scores) between the two eyes. The estimated required sample size accounted for potential dropouts and was deemed sufficient to identify within-subject differences while minimizing variability due to inter-individual factors such as disease severity, lifestyle, and systemic autoimmune status.