Repeatability and reproducibility of visual field tests in people with established visual field loss

Abstract

The thesis investigated the repeatability of the Esterman Visual Field Test (EVFT) on the Humphrey Field Analyser (HFA), and the reproducibility of the EVFT on the HFA and Henson Pro 5000 Perimeter. The reproducibility of the Ring of Sight (ROS) 24-2 full threshold (FT) examination was also evaluated. These were investigated with participants with established visual field loss (VFL) using case control studies. The reduced sensitivity that influences test-retest variability in those with VFL and differences within the perimeter methodologies, including the influence of background luminance were considered. Agreement in sensitivity threshold values or the Esterman Efficiency Scores (EES) between perimeters were analysed and pointwise analysis was undertaken. Any change in fitness-to-drive status or ability to determine/rule out disease was investigated. Principal Findings: The EVFT possesses poor repeatability and reproducibility for individuals with VFL with significant change in EES on test-retest at different sessions and significant lack of agreement when comparing EES on the HFA and the Henson Pro 5000 Perimeter. The EVFT possesses good repeatability and reproducibility in fitness-to-drive status. The significant variation in EES and location of defect in those with VFL does not impact upon on an individual’s fitness-to-drive status. It is recommended that a repeat examination is performed on the HFA for those with VFL who fails the EVFT on initial examination to account for variability of test-retest and the significantly lower EES recorded by the Henson Pro 5000 Perimeter. There is a large proportion of those with VFL (33.33%) who are unable to see a target, which is required to be seen, in order to conduct a visual field test on the ROS. There is significant lack of agreement in defect depth, defect location, mean deviation and sensitivity threshold values found on the ROS 24-2 FT examination compared to the SITA Standard 24-2 examination performed on the HFA. The ROS possesses a sensitivity value of 33.33%.