NECSUS-Neuroadaptation after Cataract and Refractive Surgery Study

Summary: Important causes of dissatisfaction after cataract surgery are dysphotopsia (glare, halos, starbursts) requiring IOL exchange in 5.7% of cases. Optical parameters per se cannot explain why symptoms are different among patients,as no differences have been found in light scatter, aberrations, residual sphere and cylinder. Attempts to link optical outcomes and dysphotopsia have not proven an association between measurable aberrations and symptoms. This suggests the involvement of other mechanisms, at the neural level.

Because these symptoms tend to improve overtime, it is thought that the brain adapts to those unwanted stimuli (neuroadaptation). In fact, our vision is determined by how the brain processes incoming retinal input, as vision involves “constructive” perception and not merely the analysis of an optically perfect image.

Neuroplasticity is the ability of the brain to reorganize its connections in response to the changing patterns of inputs from the environment. We hypothesize that multifocal IOLs engaged different forms of plasticity. Functional magnetic resonance imaging (fMRI) has opened an unprecedented opportunity for studying brain activity.

This study aims, for the first time, to identify changes in neural activity patterns after multifocal IOL implantation overtime and their relation with objective and qualitative aspects of visual function. Such information will provide valuable knowledge on the identification of therapeutic targets and of intraocular lens characteristics that are more likely to trigger neuroadaptation circuits effectively and, hence, lead to practical clinical use.