Perceptual learning leads to long lasting visual improvement in patients with central vision loss.

BACKGROUND

Macular Degeneration (MD), a visual disease that produces central vision loss, is one of the main causes of visual disability in western countries. Patients with MD are forced to use a peripheral retinal locus (PRL) as a substitute of the fovea. However, the poor sensitivity of this region renders basic everyday tasks very hard for MD patients.

OBJECTIVE

We investigated whether perceptual learning (PL) with lateral masking in the PRL of MD patients, improved their residual visual functions.

METHOD: Observers were trained with two distinct contrast detection tasks: (i) a Yes/No task with no feedback (MD: N = 3; controls: N = 3), and (ii) a temporal two-alternative forced choice task with feedback on incorrect trials (i.e., temporal-2AFC; MD: N = 4; controls: N = 3). Observers had to detect a Gabor patch (target) flanked above and below by two high contrast patches (i.e., lateral masking). Stimulus presentation was monocular with durations varying between 133 and 250 ms. Participants underwent 24- 27 training sessions in total.

RESULTS

Both PL procedures produced significant improvements in the trained task and learning transferred to visual acuity. Besides, the amount of transfer was greater for the temporal-2AFC task that induced a significant improvement of the contrast sensitivity for untrained spatial frequencies. Most importantly, follow-up tests on MD patients trained with the temporal-2AFC task showed that PL effects were retained between four and six months, suggesting long-term neural plasticity changes in the visual cortex.

CONCLUSION

The results show for the first time that PL with a lateral masking configuration has strong, non-invasive and long lasting rehabilitative potential to improve residual vision in the PRL of patients with central vision loss.