Posterior ocular structural changes and glaucoma susceptibility in patients with hemifacial spasm

To evaluate the changes in the posterior ocular structures and glaucoma susceptibility in patients with hemifacial spasm (HFS).

Prospective observational clinical study.

This study included 46 long-standing HFS patients with a minimum follow-up of 12 months. The participants' eyes were divided into three groups: (1) 46 affected eyes of patients with clinical HFS; (2) 46 unaffected fellow eyes and, (3) 46 eyes of healthy sex and age-matched controls. All participants were assessed by a detailed clinical examination and optical coherence tomography (OCT) with enhanced depth imaging (EDI). EDI-OCT images were binarized using ImageJ software. Peripapillary retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), choroidal thickness (CT), and choroidal vascularity index (CVI) were used to compare the structural characteristics of the affected eyes with fellow and control eyes. The CT measurements were performed from the subfoveal and locations at 750 μm and 3000 μm intervals from the foveal center, and the average of CT measurements at 5 locations was accepted as mean CT.

The demographic and clinical characteristics among the groups were similar (for all, P > 0.05). Mean peripapillary RNFL thickness of the inferior quarter was significantly lower in affected eyes, compared to fellow eyes (P = 0.023) and control eyes (P = 0.040). Mean GCC thickness significantly decreased in affected eyes, compared to fellow eyes (P = 0.019) and healthy controls (P = 0.008). Mean CT thickness significantly decreased in affected eyes, compared to fellow eyes (P = 0.002) and healthy controls (P < 0.001). Mean subfoveal CVI (65.94% ± 1.46) was found to be significantly thinner than the unaffected fellow (68.19% ± 1.84, P = 0.011) eyes and control eyes (67.23% ± 0.84, P = 0.044).

This study's outcomes show that long-standing HFS is associated with glaucoma-associated morphological OCT findings and decreased both CT and subfoveal choroidal vascularity. These findings may be related to the fact that the posterior ocular structures are affected by long-lasting paroxysmal orbicularis contractions.