Neuroadaptation & its role in multifocal IOL outcomes

October 1, 2008

Dr George Beiko advises on how to prepare patients for the gradual postoperative changes

Key Points

Neuroadaptation. Ophthalmologists refer to this concept on a regular basis when discussing presbyopic correction with their cataract surgery candidates. As physicians, we are aware that this phenomenon exists and that it has the potential to impact quality of vision, but in truth, many of us have a difficult time describing the process in detail and its implications for refractive surgery.

Explaining the concept

So what exactly is neuroadaptation? Essentially, it is the ability of the adult nervous system to adapt to changes in the body or the environment. On a cellular level, this translates into neuroplasticity, which is the by-product of synapse and neuronal connection shifting. The process itself is variable and can take as little as a few weeks to as long as a year in certain individuals. Optically, neuroadaptation allows patients to perceive higher quality images than one might otherwise expect from an IOL.

This is especially pertinent in the use of multifocals for refractive surgery. With this type of lens, a new visual system is introduced to the brain, one for which the visual cortex contains no pre-wired circuitry. The brain is accustomed to seeing only one image, but with multifocal lenses, it must digest two or more pictures in order to maintain visual acuity. It has to learn how to suppress near vision when gazing at distant objects and to restrict distance vision when focusing close up; a task that is made possible by neuroadaptation.