Immediate cortical adaptation in visual and non-visual areas functions induced by monovision

Area of Science:

• Neuroscience
• Ophthalmology
• Visual Science

Background:

• Monovision is a common contact lens correction for presbyopia, offering unbalanced vision correction for near and far sight.
• The underlying brain mechanisms of monovision adaptation remain poorly understood despite its widespread use.
• Monovision creates an acquired anisometropia, superimposing in-focus and blurred images.

Purpose of the Study:

• To investigate the brain's adaptation mechanisms to monovision using high-density electroencephalography (EEG).
• To analyze the spatiotemporal cortical activity following short-term adaptation to monovision contact lenses.
• To elucidate the neural basis of successful monovision correction in presbyopia.

Main Methods:

• Utilized a 64-channel high-density electrode array to measure visual evoked potentials (VEPs) in presbyopic observers.
• Compared VEPs under monovision correction with those under balanced eye near correction.
• Performed detailed spatiotemporal analysis of cortical activity.

Main Results:

• Monovision significantly reduced the amplitude of early VEP components (C1 and N1), indicating reduced feed-forward activity in the primary visual cortex and feedback activity in extrastriate areas.
• Observed a notable increase in the amplitude of later VEP components (P1 and pP1).
• The P1 component increase suggests compensatory activity in extrastriate visual areas, while the pP1 increase points to engagement of the anterior insula.

Conclusions:

• Monovision induces significant changes in early visual processing, reducing activity in primary and extrastriate visual areas.
• Increased activity in extrastriate and prefrontal regions (pP1) suggests attentional compensatory mechanisms are engaged to manage the degraded visual signal.
• These findings demonstrate the brain's remarkable adaptability to monovision, involving both visual and non-visual cortical areas.