Study: Impact of Botox on tear production
This is another interesting reminder of the step-forward, step-backward reward/risk profile - or at least potential - of many medical treatments as well as cosmetic procedures when it comes to dry eye.
Botox has an unusual relationship to dry eye. It has been used extensively to treat blepharospasm, which can indirectly improve dry eye in those who have blepharospasm, and it has been used to treat at least ten other medical conditions as well. However, it can also cause or contribute to dry eye, and there is a growing body of literature on the ways it may be doing that. Click here for more.
The study below suggests that it may decrease tear quantity, but not quality.
Effect of Botulinum toxin A application in neuro-ophtalmologic indications on Schirmers test and tears osmolarity. Žiak P et al, Cesk Slov Oftalmol. 2019 Summer;75(2):74-77.
Botulinum toxin type A (BT-A) is used in the treatment of neuro-ophthalmologic disorders such as essential blepharospasm and facial hemispasm for more than 20 years. Although the long-term effect of repeated application of the BT-A was confirmed, the BT-A effect on tears production and retention is not clear. In our work we investigated whether applied BT-A in patients with blepharospasm and hemifacial spasm affect tears production. Tears quality was measured with Schirmers and tear osmolarity test during neuro-ophthalmologic diseases treatment, which was evaluated before and 14 days after application of BT-A (Botox inj, Allergan, Irvine, USA) into the orbicularis oculi muscle. BT-A doses of 16-18 U with unilateral and 32 to 36 U bilateral applications were used. The mean tear production in Schirmers test before BT-A application was 8.38 ± 0.63 mm, and 2 weeks after BT-A application was 7.12 ± 0,6 mm (n = 50). Tear osmolarity was 305.4 ± 9.2 mOsm before BT-A application, and 2 weeks after BT-A application it was 305.2 ± 8,6 mOsm (n = 13). We found significant difference between two groups in tear quantity (p < 0.012), but not quality (p > 0.05). Application of the BT-A reduced the amount of tears measured by Schirmers test. These results confirm rational basis of the empirical clinical experience where an artificial tears substitution is recommended for patients with neuro-ophthalmologic disorders treated by BT-A.