Transcranial direct current stimulation improves visual acuity in amblyopic Long-Evans rats

Area of Science:

• Neuroscience
• Ophthalmology
• Neurostimulation

Background:

• Amblyopia, or 'lazy eye,' results from abnormal visual experience during critical developmental periods.
• Reduced visual cortex plasticity is a hallmark of amblyopia, impacting visual acuity.
• Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique known to enhance cortical plasticity.

Purpose of the Study:

• To investigate the therapeutic potential of anodal tDCS in an experimental rat model of amblyopia.
• To evaluate the impact of tDCS on visual function and acuity following early-life visual deprivation.

Main Methods:

• Long-Evans rats underwent monocular deprivation during a critical developmental window (postnatal days 12-75).
• The visual cortex contralateral to the deprived eye received anodal tDCS for 8 days (20 min/day).
• Visual acuity was assessed using the optomotor reflex in both monocular and binocular conditions.

Main Results:

• Monocular deprivation significantly reduced visual acuity in both monocular and binocular vision.
• Anodal tDCS treatment led to a near-complete recovery of visual acuity in amblyopic rats.
• In healthy control rats, the same tDCS protocol resulted in decreased binocular visual acuity.

Conclusions:

• Anodal tDCS demonstrates potential for reversing visual acuity deficits caused by monocular deprivation in an amblyopia model.
• Careful control and application are necessary due to potential adverse effects of tDCS on visual acuity in healthy individuals.