Oscillatory thresholds and foveal and macular thickness using coherence tomography

Abstract

Background: Technology is evolving and advancing rapidly as is evident in the ophthalmic and optometric fields with the development of new equipment and software programs that assist in the examination of patients and diagnoses of ocular diseases. The new vision psychophysical software for measurements of oscillatory sensitivity (OS) is a recently developed program that can be used to assess visual ability at the fovea by establishing oscillatory thresholds (OT) and it is therefore necessary to assess the reliability and repeatability of this new software.

Aim: The goal of this study was to assess the reliability and repeatability of the new vision psychophysical software for measuring OS with special focus on the macular and foveal area.

Setting: This study took place at the Department of Optometry at the University of Johannesburg between 2016 and 2017.

Methods: To measure OS, an ascending threshold method was used where a simple target was presented, with increasing oscillations until perception of movement occurred. Healthy participants (N = 37), with a mean age of 22.43 ± 2.57 years, were asked to indicate when the high contrast circular (2 mm) target began oscillating on a stationary black background. The target was used at nine points in the macular region to measure OT. Each macular map was measured twice per participant and only the right eyes were involved. Retinal thicknesses were also evaluated using the spectral-domain iVue 100 optical coherence tomography (OCT) from Optovue. Macular thickness and OS (along with OT) measurements were assessed using various graphical and statistical methods to establish test–retest reliability and repeatability.

Results: The study focused on OS and retinal thickness measurements of the macular and foveal regions. For retinal thickness measurements, repeatability and reliability were good, data was normally distributed and agreement between test–retest measurements was high, while OS measurements had good repeatability and reliability, were not normally distributed but had good agreement between test–retest measurements. With healthy participants, no correlations between OCT and OS measurements were found (r = −0.14, p = 0.49 and r = 0.03, p = 0.89 for test and retest samples).

Conclusion: The results for both procedures suggest that there is good reliability and repeatability within the macular region. Both methods can be used with confidence clinically and in future studies.