Dr. Chaokai Chang began his work in ophthalmology in 2001. He sought to non-invasively measure the amount of lutein and zeaxanthin (macular pigment) in a human retina. He found that best method was based on a psychophysical technique: a subject’s behavioral response to a visual stimulus. He found that macular pigment was influencing vision in a linear fashion.

Since macular pigment is a yellow filter anterior to the cone photoreceptors, Dr. Chang hypothesized that it protects the eyes from ultraviolet light,  like internal sunglasses. His hypothesis was confirmed in a series of randomized trials that showed that increasing macular pigment directly reduces visual disability due to glare, and speeds recovery from blinding flashes of intense light.

These studies, from our laboratory and others, show that macular pigment has a basic function in the normal operation of the retina. Hence, deficiency in lutein/zeaxanthin intake would have implications for vision and eye health. We are currently extending this work to look at additional roles of lutein within the central nervous system such as visual-motor function, processing speed, and brain function.