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New imaging system corrects for chromatic aberrations

A new imaging system capable of cancelling out the chromatic aberrations present in a person’s eye promises to provide more accurate assessments of both vision and eye health.

The system, developed by researchers from the University of Washington, also provides the first objective measurement of longitudinal chromatic aberrations (LCA). It is hoped that it could lead to new understandings of their relationship to visual halos, glare and colour perception.

“The previous methods of compensating the eye’s native LCA rely on population average estimates, without individualised correction on a person-by-person basis,” Dr Ramkumar Sabesan, research team leader, said.

“We demonstrate a modified filter-based Badal optometer that offers the capability to tune LCA across different wavelength bands and for each individual in a customised fashion.”

By changing the distance between the two lenses of a Badal optometer, focus can be changed with altering the size of the viewed image. The team behind the project modified a Badal optometer by adding two filters that transmit longer wavelengths, while refracting shorter ones.

In the modified system, when the distance between the two lenses is changed, the transmitted reflected wavelength bands have different levels of focus, which compensates for the eye’s native chromatic aberration.

By finely tuning factors such as filters, distances between lenses and colour illumination, the setup can be used to measure and compensate for LCA.

The team behind the project claim the technology could easily be deployed in either the clinic or laboratory for colour vision assessment and research. Potential applications include assessing changes in the eye associated with aging, as well as informing the design of new multifocal lens that could correct for chromatic aberrations.

“Our study establishes a flexible tool to compensate for chromatic aberration in different wavelength bands and in an individualised manner, thus facilitating future investigations into how we see colour in our environment, unimpeded by the native chromatic imperfections of the individual,” Sabesan said.

“Now equipped with the tools to control chromatic aberration, we plan to conduct studies on normal and deficient colour vision.”

The research was published in the Optical Society journal Optica.

IMAGE: Dr Ramkumar Sabesan from the University of Washington.

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