Repetitive visual cortex transcranial random noise stimulation in adults with amblyopia

Area of Science:

• Neuroscience
• Ophthalmology
• Medical Devices

Background:

• Amblyopia, or 'lazy eye,' affects visual development and can persist into adulthood.
• Non-invasive brain stimulation techniques are being explored to enhance visual function in amblyopia.
• Transcranial random noise stimulation (tRNS) is a neuromodulation method applied to the scalp.

Purpose of the Study:

• To investigate the efficacy of daily visual cortex tRNS in improving visual functions in adults with amblyopia.
• To assess short-term and long-lasting effects of tRNS on contrast sensitivity and visual acuity.

Main Methods:

• Nineteen adults with amblyopia received either active or sham tRNS of the visual cortex over five consecutive days.
• Visual outcomes, including contrast sensitivity and crowded/uncrowded visual acuity, were measured before, during, and after stimulation sessions.
• A 28-day follow-up was conducted to assess sustained treatment effects.

Main Results:

• Active tRNS significantly improved contrast sensitivity and uncrowded visual acuity in both amblyopic and fellow eyes, with sham tRNS showing no effect.
• Initial improvements were observed within sessions, particularly on day 1, but these effects generally waned over subsequent days.
• A long-lasting improvement in uncrowded visual acuity of the amblyopic eye was noted at 28 days, though baseline differences complicate interpretation. No effects on crowded visual acuity were found.

Conclusions:

• Daily tRNS can induce short-term improvements in contrast sensitivity and uncrowded visual acuity in adult amblyopia.
• Repeated tRNS sessions did not yield enhanced or sustained benefits for most visual measures.
• While some long-term gains in uncrowded acuity were observed, further research is needed to optimize tRNS protocols for amblyopia treatment.