While automated perimetry has been the standard to track visual field loss, researchers from the UK and New Zealand report ocular motor reflex testing may be a reliable—and less demanding and time-consuming—alternative.
Since eyes constantly and reflexively track movement, this study, presented last week at ARVO 2019, found a reduction in eye movements consistently showed peripheral vision loss, indicating glaucoma.
Researchers tested 41 patients with asymmetric visual field loss from primary open-angle glaucoma. The ophthalmologic exam included static automated perimetry, biomicroscopy and optical coherence tomography. Investigators recorded eye movements during a visual stimulus that involved horizontal drift of fixation targets and measured optokinetic nystagmus during the test. They used fixation data to estimate optokinetic nystagmus gain (speed of slow-phase tracking eye-movements relative to target speed).
The study found optokinetic nystagmus gain was lower when patients used their more affected eye. This difference was pronounced at intermediate levels of contrast (between 6% and 25%). Researchers also reported the differences in optokinetic nystagmus gain across eyes correlated with the difference in visual field index across eyes in all but the lowest (3%) contrast condition.
Glaucomatous visual field loss was associated with slower tracking during optokinetic nystagmus: the greater the loss, the slower the tracking, researchers noted in their ARVO abstract. As a means of quantifying field loss, optokinetic nystagmus tests have the potential to overcome several shortcomings of perimetry, since they are not dependent on patients maintaining fixation or making reliable subjective judgments, they added.
|Dakin ST, Doustkouhi SM, Kersten H, et al. Measuring visual field loss in glaucoma using involuntary eye movements. ARVO 2019. Abstract 2468-A0632.|