The effect of botulinum neurotoxin A injections on meibomian glands and dry eye.

[PURPOSE] To assess the influence of Botulinum neurotoxin A (BoNT-A) injection on meibomian gland function and dry eye in patients diagnosed with Blepharospasm (BPS) and Hemifacial spam (HFS).

[METHODS] Adult patients aged 18 years or older who suffer from periocular dystonia, and were treated with BoNT-A injections, were recruited in this interventional prospective study between 2023 and 2024. Each patient was followed up for a period of three months. The following parameters were compared at baseline, 14 and 90 days post BoNT-A injections: Visual acuity, meibography, tear break up time (TBUT), Schirmer test, meibum expression, tear meniscus height, fluorescein corneal staining, meibomian gland dysfunction (MGD) grading, and ocular surface disease index (OSDI). In addition, patients underwent subjective quality of life questionnaire for BPS and HFS.

[RESULTS] Thirty-six eyes of twenty-six patients were included in this study. The mean age ±SD was 59 ± 17.33 years. There was a significant statistical difference in vascular changes on the lid margin, TBUT, corneal and conjunctival fluorescein staining and meibum expression (P < 0.001 in all). The differences were statistically significant when compared to baseline vs visit 2, and visit 2 vs visit 3 (p-value<0.05). Jankovic rating scale and HFS score improved significantly between the time periods (P < 0.001 in both). There was no significant difference in meibomian gland loss, tear meniscus height, Schirmer test, and OSDI.

[CONCLUSION] BoNT-A injection is an effective treatment for periocular dystonia, but it worsens ocular surface and dry eye disease. Moreover, it affects the meibomian glands by disturbing their secretion.