# Short-Term Effects on Tear Film Following Cosmetic Botulinum Toxin Injections in Healthy Individuals

## TL;DR

This study examines how cosmetic botulinum toxin injections affect tear film and eye health in the short term.

## Contribution

The study reveals time-dependent changes in tear production and dry eye symptoms following botulinum toxin injections.

## Key findings

- Tear production increased shortly after injection but decreased later.
- Dry eye symptoms worsened in the months following treatment.
- Tear film stability declined in the 1-3 and 3-6 month post-injection periods.

## Abstract

Purpose: Botulinum toxin-A (BoNT-A) injections have become increasingly popular for cosmetic treatments in the upper face region, particularly for reducing wrinkles and achieving aesthetic improvements. While the cosmetic benefits are well-documented, the potential effects of these injections on ocular surface health and tear film dynamics remain incompletely understood. This study aimed to comprehensively investigate the impact of BoNT-A injections on tear film parameters and ocular surface health across different time intervals following treatment.

Materials and methods: This cross-sectional study evaluated 80 participants divided into four groups of 20 each. Three groups consisted of patients who had received upper face BoNT-A injections within the previous six months, evaluated at different time intervals: group 1 (0-1 month post-injection), group 2 (1-3 months post-injection), and group 3 (3-6 months post-injection). The fourth group served as an age- and gender-matched control group with no history of BoNT-A treatment. A comprehensive assessment of ocular surface health was conducted using three standardized parameters: the Schirmer test (without anesthesia) for tear production, the tear break-up time (TBUT) for tear film stability, and the Ocular Surface Disease Index (OSDI) for symptom evaluation. All participants underwent standardized BoNT-A injection protocols, receiving a total of 50 units administered by the same experienced cosmetic surgeon.

Results: Significant differences in tear production were observed, with the 0-1 month post-injection group exhibiting the highest mean Schirmer score (18.35±7.63 mm), compared to 12.9±3.64 mm in the control group (p<0.01). TBUT measurements revealed greater tear film stability in the control (11.35±2.92 seconds) and 0-1 month (11.05±2.97 seconds) groups compared to the 1-3 and 3-6 month groups (p<0.05). OSDI scores indicated increased symptom severity in the 1-3 month (18.62±7.04) and 3-6 month (18.82±6.08) post-injection groups compared to the control group (11.82±2.67) (p<0.001).

Conclusions: Cosmetic BoNT-A injections can lead to alterations in tear film dynamics and ocular surface health, with effects varying across different post-injection time periods. The findings suggest an initial increase in tear production followed by potential alterations in tear film stability and increased dry eye symptoms in the months following treatment. These effects appear to vary over time following injection. Further research is now needed to fully elucidate the long-term impact of cosmetic BoNT-A injections on the ocular surface.