Differences in Corneal Parameters Between Affected and Normal Contralateral Eyes in Patients With Hemifacial Spasm Treated With Botulinum Toxin-A: Outcomes During One Complete Treatment Cycle.

Abstract

To investigate possible temporary differences in corneal topographic parameters between affected and normal eyes in patients with hemifacial spasm (HFS) treated with botulinum toxin-A (BTX-A), over the course of 1 treatment cycle. This prospective study evaluated corneal topographic differences between affected and normal contralateral eyes during a 4-month period in patients with HFS treated with BTX-A (the duration of action of BTX-A for HFS ranges from 2 to 4 months). Corneal topographic analysis was performed using a conventional topographer (Atlas; Carl Zeiss Meditec, Dublin, CA). Steep K and astigmatism measurements were evaluated before BTX-A application and after 15 days and 2, 3, and 4 months. Twenty-four patients (16 women and 8 men) were evaluated. Steep K [46.9 ± 3.6 diopters (D)] and astigmatism values (2.6 ± 2.5 D) were significantly higher in affected eyes of HFS patients than in nonaffected eyes (45.0 ± 1.4 D and 0.9 ± 0.6 D) before treatment (P = 0.001 for steep K and P = 0.0003 for astigmatism). Astigmatism values also showed significant differences between the affected eye (1.4 ± 0.8 D) and nonaffected eye (0.9 ± 0.6 D) at 4 months (P = 0.006), whereas steep K showed significant differences between both eyes at 15 days (affected eye: 45.6 ± 1.5 D, nonaffected eye: 45.0 ± 1.4 D, P = 0.008), 3 months (affected eye: 45.6 ± 1.8 D, nonaffected eye: 45.1 ± 1.3 D, P = 0.03) and 4 months (affected eye: 45.8 ± 1.2 D, nonaffected eye: 45.1 ± 1.4 D, P = 0.003) after treatment. The differences in steep K, and especially in astigmatism values, between eyes tended to reduce during the period of action of BTX-A. At 4 months, when the BTX-A effect is considered to be over or very reduced, a significant difference between eyes for both parameters was noted again.