[Blink patterns in mild thyroid-associated ophthalmopathy-related dry eye and their association with tear film...

Objective: To analyze the differences in blink patterns among patients with mild thyroid-associated ophthalmopathy (TAO, with eyelid retraction<2 mm), patients with primary dry eye disease (DED), and non-dry-eye controls, and to explore the association between these patterns and tear film stability. Methods: The data of patients who were admitted to the Department of Ophthalmology at Ningbo Medical Center Lihuili Hospital between July and September 2025 were retrospectively collected. Based on clinical features, patients were classified into three groups: mild TAO group, primary DED group, and non-dry-eye control group. All subjects underwent standardized ocular surface assessments. Dry eye-related parameters were measured, and spontaneous blink frequency and incomplete blink ratio were quantified. Intergroup differences were compared, correlations between blink patterns and dry eye parameters were analyzed, and multiple linear regression was performed to identify factors associated with incomplete blink ratio. Results: A total of 140 patients (140 eyes) were included. The mild TAO group comprised 45 patients (45 eyes; 19 males and 26 females), with a median age of 45 (31, 50) years. The primary DED group comprised 45 patients (45 eyes; 18 males and 27 females), with a median age of 40 (32, 54) years. The non-dry-eye control group comprised 50 subjects (50 eyes; 19 males and 31 females), with a median age of 40 (30, 50) years. No significant differences were observed in age or sex among the three groups (all P>0.05). Between the mild TAO group and the primary DED group, no significant differences were found in Schirmer test results, tear meniscus height, ocular redness score, meibomian margin morphology score, lipid layer saturation, or lipid spread speed (all P>0.05). However, non-invasive tear film breakup time (NIBUT) was significantly shorter in the mild TAO group than in the primary DED group [2.0 (2.0, 2.5) s vs 4.2 (2.4, 6.0) s, P<0.001]. The meibomian gland area ratio was higher in the mild TAO group than that in the primary DED group (P<0.001), but was comparable to that in the non-dry-eye control group (P=0.051). Blink frequency was lower in the mild TAO group than those in both the primary DED group (P=0.026) and the non-dry-eye control group (P<0.001). The incomplete blink ratio in the mild TAO group [50.0% (31.7%, 70.7%)] was significantly higher than that in the primary DED group [16.7% (7.7%, 26.7%)] and the non-dry-eye control group [5.6% (0, 11.1%)] (both P<0.001). In the mild TAO group, the incomplete blink ratio was strongly negatively correlated with NIBUT (rₛ=-0.826, P<0.001) and positively correlated with ocular surface disease index (OSDI) score (rₛ=0.320, P=0.032). Multiple linear regression showed that shortened NIBUT (β=-0.061, 95%CI:-0.093--0.029, P<0.001) and reduced blink frequency (β=-0.042, 95%CI:-0.053--0.030, P<0.001) were independently associated with an increased incomplete blink ratio. Conclusion: In patients with mild TAO who have minimized mechanical exposure (eyelid retraction<2 mm), an abnormal blink pattern characterized by increased incomplete blink ratio and decreased blink frequency is observed, and this pattern is significantly correlated with reduced tear film stability.