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Effects of periocular botulinum toxin injection on ocular surface parameters and pupillary dynamics: a prospective
Caner Karakaya1, Isik Yildirim2
1Department of Ophthalmology, Esenler Hospital, Istanbul Medipol University, Birlik Mahallesi, Bahceler Caddesi, No: 5, Esenler, Istanbul, Turkey. dr-karakaya@hotmail.com.
Purpose:
To evaluate the effects of periocular botulinum toxin injection on ocular surface parameters and pupillary dynamics, and to explore its potential neuro-autonomic implications.
Methods:
In this prospective interventional study, 26 eyes from 13 patients undergoing cosmetic periocular botulinum toxin injection were evaluated. Ocular surface parameters, including tear breakup time (TBUT) and Schirmer test, and pupillometric measurements (dynamic and static) were assessed before injection and at 20 days post-treatment under standardized conditions.
Results:
Following botulinum toxin injection, both TBUT and Schirmer test values decreased significantly (P < 0.001 for both), indicating deterioration of ocular surface function. Dynamic pupillometry revealed a significant increase in minimum pupil diameter (P = 0.001), while maximum pupil diameter showed a non-significant change (P = 0.318). Mesopic pupil diameter increased significantly (P = 0.046), whereas photopic pupil diameter did not reach significance (P = 0.557). Notably, pupil constriction velocity increased significantly (P = 0.030), suggesting enhanced pupillary responsiveness, while dilation velocity increased but did not reach statistical significance (P = 0.107). All analyses were performed using generalized estimating equations to account for inter-eye correlation.
Conclusion:
Periocular botulinum toxin injection was associated with significant deterioration in ocular surface parameters and measurable alterations in pupillary dynamics, including increases in minimum and mesopic pupil diameters and constriction velocity, supporting combined mechanical and neuro-autonomic effects. These findings highlight the importance of considering both ocular surface and autonomic effects when evaluating the safety profile of cosmetic botulinum toxin applications.
