The Brain Works as a “Cyclops”

By Sondra Forsyth

Although the eyes differ in their optical properties, the visual system calibrates itself. Research performed by the Spanish National Research Council has discovered that when each eye separately has a different level of blur, the brain uses the image projected through the less aberrated eye as the reference for sharpness. The study was published in March 2015 in Current Biology.

A release from the council quotes researcher Susana Marcos of the Instituto de Óptica Daza de Váldes as saying, “Our impression about what is sharp is . . .  determined by the sharper image [of] those [that] are projected through both eyes.” The research reveals that, despite these blur differences, the perception of each eye separately about the sharper image is the same, regardless of the eye we use to make the test.

The nature of these visual calibrations is important in order to understand the different consequences referred to the refractive errors between both eyes. For instance, an available solution to correct presbyopia is monovision, in which different refractive corrections are provided for each eye. The dominant eye is corrected for distance viewing and the other one is corrected for close viewing. “It is essential to understand the visual calibration with different levels of blur to understand the visual processing of the patients, the main objective is to provide the best possible correction”, concludes the researcher.