Abstract
Purpose :
Congenital nystagmus (CN) is an ocular-motor disorder that presents at birth or early infancy. At present, the main surgical treatments for CN are null zone shifting and tenotomy-reattachment surgery. Until now, there has been no effective and curative approach for diminishing involuntary oscillations of CN without ocular muscle injury.
Methods :
We enrolled 6 patients with CN (all of whom had been diagnosed with a mutation in FERM domain containing 7 (FRMD7)). Vagus nerve stimulation (VNS) electrodes mimicking an ocular muscle stimulator were placed such that they encircled both the lateral and medial recti of the right eye. Ocular muscles received different levels of energy stimulation based on each patient’s clinical data. Preoperative and postoperative clinical data were recorded for both eyes, including nystagmus amplitude, nystagmus frequency and foveation time. Repeated measures analysis of variance was used to assess the study data.
Results :
After stimulation, decreases in both mean nystagmus frequency (2.75±0.53 Hz vs. 4.27±1.81 Hz, P<0.05) and mean nystagmus amplitude (1.46±1.31° vs. 3.02±2.44°, P<0.05) were observed. Mean foveation time was 0.12±0.13 ms before stimulation but was prolonged to 0.37±0.24 ms after stimulation (P<0.05). All 3 of these main clinical efficacy indices varied with different stimulation parameters. No adverse effects were observed.
Conclusions :
The electrical stimulation of ocular muscles is a novel reversible therapeutic option for effectively diminishing involuntary oscillations of CN by minimizing the side effects of traditional surgical therapy.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.