Reaction time during semi-automated kinetic perimetry (SKP) in patients with advanced visual field loss

This study aimed to evaluate reaction time (RT) in patients with advanced visual field (VF) loss using semi-automated kinetic perimetry (SKP).

Seventy-eight patients with advanced VF loss caused by glaucoma (31) or retinitis pigmentosa (19), homonymous VF loss caused by post-chiasmal lesions (18) and unilateral anterior ischaemic optic neuropathy (AION) (10) were examined with SKP (Octopus 101 perimeter). One eye in each patient was enrolled. Additionally, VFs in the 10 healthy fellow eyes of the patients with AION were compared with those in the 10 affected eyes. Reaction time was assessed during the SKP session by presenting kinetic stimuli (III4e) with constant angular velocities of 3 degrees /second moving linearly along so-called 'RT vectors' at four different locations inside the III4e isoptre. Each stimulus presentation was repeated four times in randomized order.

The geometric mean RT was 794 ms (95% reference interval [RI] 391-1615 ms) in patients with glaucoma, 702 ms (95% RI 306-1608 ms) in patients with retinitis pigmentosa and 675 ms (95% RI 312-1460 ms) in patients with hemianopia. Increases in RT for every 1 degree of eccentricity were 1%, 0.9% and 0.4%, respectively. The geometric mean RT in the 10 patients with unilateral optic neuropathy was 644 ms in affected eyes and 435 ms in unaffected eyes, reflecting an increase of 51% (95% confidence interval 42-62%).

We found substantial inter-subject variability in RT in patients with advanced VF loss. It is possible to correct the position of the isoptres by assessing individual RT. There were no relevant differences in RT between the disease groups. Reaction time increases with eccentricity. In monocular disease (AION), RT is prolonged, compared with in healthy fellow eyes. However, in clinical routine the RT-related displacement of isoptres is negligible in the vast majority of cases.