Ocular vestibular evoked myogenic potentials in different types of amblyopia

The visual system plays an important role in the development of the vestibular-ocular reflex (VOR). In clinical practice, the ocular vestibular evoked myogenic potential (oVEMP) test is used to assess contralateral VOR.

This study sought to compare the oVEMP in patients with anisometropic, strabismic, and mixed amblyopia using unilateral and bilateral (simultaneous binaural) stimulation.

Forty-two amblyopic patients (20 males and 22 females) with a mean age of 10.48 ± 4.00 years (range: 5 - 20 years) were examined. The Titmus stereopsis test, alternate cover test, and best-corrected visual acuity were evaluated. Patients were divided into three groups: anisometropic, strabismic, and mixed amblyopia. The oVEMP responses including the amplitude of electrical activity (n1-p1 complex) and the latencies (n1 and p1) of the VOR responses were recorded under unilateral and bilateral stimulations.

In the anisometropic and strabismic group, n1 latency was significantly faster in the non-amblyopic eyes compared to amblyopic eyes (Z = -2.04, p = 0.042, andZ = -2.54, p = 0.024 respectively). Mean p1 latency was significantly faster in the non-amblyopic eyes compared to the amblyopic eyes of the strabismic group (Z = -2.31, p = 0.011)In all groups, the p1 latency was faster in the non-amblyopic eye compared to bilateral stimulation (all, p < 0.05). In all groups, the n1-p1 amplitude was not significantly different between the two eyes, and between each eye and bilateral stimulation (all, p > 0.05). No significant correlation was found between the depth of amblyopia and n1 and p1 responses (all, p > 0.05). In all groups there was no significant difference in the latency of n1 and p1 between the amblyopic eye and bilateral stimulation (all, p > 0.05).

Regardless of its type, amblyopia affects vestibular-ocular reflex responses. Further research is warranted to clarify the effect of the disease and its treatment on the ocular-vestibular system.