Keratoconus progression is not inhibited by reducing eyelid muscular force with botulinum toxin A treatment: a randomized trial

Purpose:: To evaluate whether reducing eyelid muscular force through the administration of botulinum toxin type A (BTX-A) to the orbicularis oculi muscles of patients with keratoconus affected corneal parameters indicative of disease progression. Methods:: In this prospective parallel randomized clinical trial, 40 eyes of 40 patients with keratoconus were randomized into equally sized control and BTX-A groups. Patients in the BTX-A group received subcutaneous BTX-A injections into the orbicularis muscle. The control group received no intervention. Palpebral fissure height, best spectacle-corrected visual acuity (BSCVA), and corneal topographic parameters were evaluated at baseline and at 3-, 6-, 12-, and 18-month follow-ups. Results:: The mean ± standard deviation vertical palpebral fissure heights were 9.74 ± 1.87 mm and 9.45 ± 1.47 mm at baseline in the control and BTX-A groups, respectively, and 10.0 ± 1.49 mm and 9.62 ± 1.73 mm at 18 months, with no significant difference between the groups (p=0.337). BSCVA values were 0.63 ± 0.56 and 0.60 ± 0.27 at baseline in the control and BTX-A groups (p=0.643), and 0.52 ± 0.59 and 0.45 ± 0.26 at 18 months, again with no significant difference between the groups (p=0.452). In addition, there were no statistical differences between the groups at 18 months for the three keratometry topographic parameters: flattest (K1), steepest (K2), and mean (Km) keratometry (p=0.562). Conclusion:: BTX-A inhibition of eyelid force generation did not result in detectable changes in corneal parameters in keratoconic patients during 18 months of follow-up.