Visual searching capabilities in Age-Related Macular Degeneration (AMD) subjects.

A decrease in visual perception with age was observed due to a decline in neurocognitive and visual functions. Previous studies showed that aging affects visual processes and contextual perceptual phenomena. The aim of our study was to explore the effect of age as well as the effect of Age-Related Macular Degeneration (AMD) on the visual searching task. Three groups of twenty-one subjects were recruited: AMD subjects (mean age 72.29 ± 4.83 years); healthy elderly (72.55 ± 4.95); and young healthy volunteers (28.38 ± 2.77). Visual perception functions were evaluated with a modified barrage test developed by Metrisquare. Our results showed that AMD patients and elderly do not differ in terms of time, omissions and errors. However both were slower to perform the visual perception tests when compared with young adults. Regarding the number of errors and omissions, we only found significant differences between the young and the AMD subjects, the later making more omissions and errors respect to young healthy volunteers. Despite AMD patients made more errors likely because to their poor fixation capability, we could conclude that AMD patients, as well as healthy elderly subjects, could compensate their altered visual strategies by taking more time to perform the visual searching tasks, probably due to cortical plasticity.HighlightsAMD patients and healthy elderly subjects do not differ in terms of time, omissions and errors.AMD patients, as well as healthy elderly subjects could compensate their visual difficulties by taking more time to perform the visual searching tasks when compared to young healthy volunteers. It is probably due to cortical plasticity.Note, however that AMD patients could make more errors when compared to young healthy volunteers, probably due to their poor fixation capability.The number of omissions and errors not different in healthy young and in elderly subjects.

Effect of Visual Search Training on Saccades in Age-related Macular Degeneration Subjects.

OBJECTIVE: To compare the impact of unilateral versus bilateral Age-related Macular Degeneration (AMD) on saccadic movements, and to show the effect of visual search training on these eye movement performances in AMD subjects. We hypothesized that unilateral and bilateral AMD subjects had abnormal saccadic performances, and that visual search training could improve their performances. METHODS: Three groups participated in visual search training: 13 elderly unilateral AMD subjects (mean age: 74.6 ± 1.6 years), 15 elderly bilateral AMD subjects (mean age: 74.2 ± 1.2 years), and 15 healthy age-matched control subjects (mean age: 70.9 ± 1.3 years). Horizontal saccadic performances were recorded before and after visual search training (Metrisquare®) with the Mobile Eye Tracker (Mobile EBT®). We analyzed the saccadic movement performances: latency, mean velocity and gain. We measured the training performances for each exercise: the time, the number of omissions and the number of errors. We analyzed the performances with Kruskal-Wallis and posthoc tests. RESULTS: The latency of saccades in AMD subjects is significantly longer compared to healthy elderly for 15° (p<0.03), 10° (p<0.003) and 5° (p<10-3). Unilateral and bilateral AMD subjects normalized their latency of saccades after training for small saccades (respectively p=0.30 and p=0.23 for 10°, and p=0.09 and p=0.52 for 5°). In elderly, performances depend on the saccade's amplitude. CONCLUSION: AMD subjects' saccadic movements are disrupted: the execution needs more time but is efficient. The visual search training improved the saccadic performances in AMD subjects. Further studies will aim to improve knowledge on such issues and to explore the benefit of training over time in unilateral AMD subjects.

Effects of Age-Related Macular Degeneration on Postural Sway.

Purpose: To compare the impact of unilateral vs. bilateral age-related macular degeneration (AMD) on postural sway, and the influence of different visual conditions. The hypothesis of our study was that the impact of AMD will be different between unilateral and bilateral AMD subjects compared to age-matched healthy elderly. Methods: Postural stability was measured with a platform (TechnoConcept®) in 10 elderly unilateral AMD subjects (mean age: 71.1 ± 4.6 years), 10 elderly bilateral AMD subjects (mean age: 70.8 ± 6.1 years), and 10 healthy age-matched control subjects (mean age: 69.8 ± 6.3 years). Four visual conditions were tested: both eyes viewing condition (BEV), dominant eye viewing (DEV), non-dominant eye viewing (NDEV), and eyes closed (EC). We analyzed the surface area, the length, the mean speed, the anteroposterior (AP), and mediolateral (ML) displacement of the center of pressure (CoP). Results: Bilateral AMD subjects had a surface area (p < 0.05) and AP displacement of the CoP (p < 0.01) higher than healthy elderly. Unilateral AMD subjects had more AP displacement of the CoP (p < 0.05) than healthy elderly. Conclusions: We suggest that ADM subjects could have poor postural adaptive mechanisms leading to increase their postural instability. Further studies will aim to improve knowledge on such issue and to develop reeducation techniques in these patients.