OCT errors identified

High myopes may yield inaccurate results when their discs are scanned by an OCT.

A study in this month's British Journal of Ophthalmology looked at the nerve fibre layer thickness around the discs of 255 myopes using the Cirrus HD-OCT. Results were compared to those produced by cross-sectional optic nerve imaging. In 17.6 per cent of cases there were neuro-retinal rim measurement errors. The presence of peripapillary atrophy, higher ametropia and greater axial length were all found to be associated with errors in detecting the margin.

The high rates of abnormal RNFL scans have led the authors to call for caution, particularly when attempting to diagnose glaucoma in myopic eyes using these devices.