MOTION PERCEPTION IN DRY AGE-RELATED MACULAR DEGENERATION

Abstract

 

Purpose

 

To investigate the speed discrimination performance in peripheral fields of patients with dry age-related macular degeneration (AMD).

 

Methods

 

Fifty-two participants were recruited for this prospective cross-sectional study; 18 AMD patients, 18 age-matched controls and 16 young controls. Initial clinical assessment included the measure of best-corrected visual acuity (BCVA) with ETDRS chart. The contrast sensitivity (CS) was also evaluated with sine-wave gratings chart for five spatial frequencies (1.5, 3, 6, 12 and 18 cycle per degree). Optic coherence tomographic (OCT) scans and visual field (VF) examinations were performed for all participants to exclude presence of other ocular diseases. At the time of the study, all participants held a valid driver’s license. Speed discrimination performance was assessed by a two-alternative forced choice paradigm. Random dot cinematograms used as speed stimuli moved from the center to the periphery.

 

Results

 

Patients with AMD had significant worse BCVA and CS outcomes than age-matched and young controls. On average, the AMD group showed lower speed discrimination thresholds compared with age-matched control (p=0.04). The spread and the bias of the resulting psychometric function were not significantly different between the study groups (p>0.05). A tendency to overestimate speeds in both control groups and to underestimate speeds in AMD group was also observed.

 

Conclusions

 

This study presents psychophysical evidence for better speed discrimination in peripheral fields of patients with AMD compared to their age-matched controls. In addition, these data highlight the importance of peripheral vision in AMD even for mild to moderate central visual loss.

 

Keywords: 412 age-related macular degeneration • 760 visual search • 466 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials