August 2018


News in brief

Need another reason to eat chocolate?

The health benefits of dark chocolate consumption now extend to visual acuity, according to research published in JAMA Ophthalmology.1 A randomized crossover clinical trial involving 30 adults evaluated the short-term visual effects of chocolate consumption—milk vs. dark. Rabin et al. found significantly higher small-letter contrast sensitivity and slightly better large-letter contrast sensitivity, measured within 1.75 hours after eating the candy, in the group that ate dark chocolate compared to the group consuming the lighter variety. Visual acuity improved slightly in both groups. Rabin et al. concluded that “contrast sensitivity and visual acuity were significantly higher 2 hours after consumption of a dark chocolate bar compared with a milk chocolate bar, but duration of these effects and their influence in real-world performance await further testing.”

Intraocular implant takes inspiration from nanostructures on butterfly wings

The glasswing butterfly’s wings are transparent, as its name implies. Radwanul Siddique, PhD, California Institute of Technology, Pasadena, California, several years ago sought to figure out how this effect was achieved, identifying that the wings were composed of biophotonic nanostructures, 100 nanometers in diameter and 150 nanometers apart, that redirected light in a way that there was almost no reflection. The concept—angle- independent antireflection—was picked up by Hyuck Choo, PhD, visiting associate in electrical engineering, California Institute of Technology, who began research to evaluate the application of these properties in a medical implant, specifically one that could allow for at-home IOP monitoring. According to the university’s press release, the intraocular implant is drum-shaped and the width of just a few strands of human air. The surface of the implant changes with fluctuating IOP, and these changes are measured with a handheld device. The nanostructures inspired by the glasswing butterfly allow the external device to take measurements of the implant’s changes from any angle. “The nanostructures unlock the potential of this implant, making it practical for glaucoma patients to test their own eye pressure every day,” Dr. Choo said in the university’s press release. The nanostructures, which in this case are hydrophilic and made from silicon nitride, are biocompatible and resist biodegradation. This sensor has been tested in a rabbit model, according to research published in Nature Nanotechnology.2

More insights on myopia

Two new studies add to the body of research regarding risk of myopia. One, published in Nature Genetics, announced the discovery of 161 genetic factors associated with myopia.3 The research from investigators at Johannes Gutenberg University Mainz, Germany, quadruples the number of previously known genetic factors associated with the risk of developing myopia, according to the university’s press release. Most of these genes are associated with light processing, which the researchers said supports the link between natural light exposure and myopia prevention. “Send your kids to play outside for 2 hours every day. And it’s not just their eyes that will benefit,” said Norbert Pfeiffer, MD, study co-author, Department of Ophthalmology, Johannes Gutenberg University Mainz. A second study published in the British Medical Journal sought to evaluate years of education and myopia risk.4 The research, which used publicly available genetic data, evaluated a cohort of nearly 68,000 people from the U.K., basing analysis on their gene variants for myopia, years of completed education, and refractive error. Mountjoy et al. concluded the “study shows that exposure to more years in education contributes to the rising prevalence of myopia. Increasing the length of time spent in education may inadvertently increase the prevalence of myopia and potential future visual disability.”

Eyes could aid in schizophrenia diagnosis

There is a growing body of research that is using the eye as a window to the brain for early diagnosis of various neurological disorders, such as Parkinson’s disease. Research published in the Journal of Abnormal Psychology by investigators from Rutgers University, New Brunswick, New Jersey, found that a handheld device that records electrical activity from the retina (RETeval, LKC Technologies, Gaithersburg, Maryland) might someday be useful in the diagnosis of schizophrenia.5 “Since the retina is part of the nervous system, what is happening in the retina is likely reflective of what is occurring in the brain,” Steven Silverstein, PhD, professor of psychiatry, Rutgers Robert Wood Johnson Medical School, said in a press release. “For example, we know that certain changes in the retina, like thinning tissue [due to cell loss] or weakening electrical activity, occur alongside loss of brain tissue and reduced brain activity in patients with neurological disorders like multiple sclerosis and Parkinson’s disease. We and other researchers are now investigating whether retinal changes are related to brain structure and function changes in schizophrenia.” At this stage, the research determined that the device could be used to differentiate between those who had schizophrenia and those who didn’t.

Vision loss related to stress

The stress of experiencing vision loss due to a degenerative, progressive disease could actually add to vision loss, research published in the European Association for Predictive, Preventative and Personalised Medicine Journal found.6 Sabel et al. performed a literature review and concluded that “stress is both consequence and cause of vision loss.”


1. Rabin JC, et al. Effects of milk vs. dark chocolate consumption on visual acuity and contrast sensitivity within 2 hours: A randomized clinical trial. JAMA Ophthalmol. 2018;136:678–681.
2. Narasimhan V, et al. Multifunctional biophotonic nanostructures inspired by the longtail glasswing butterfly for medical devices. Nat Nanotechnol. 2018;13:512–519.
3. Tedja MS, et al. Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error. Nat Genet. 2018;50:834–848.
4. Mountjoy E, et al. Education and myopia: assessing the direction of causality by mendelian randomisation. BMJ. 2018;361:k2022.
5. Demmin DL, et al. Electroretinographic anomalies in schizophrenia. J Abnorm
Psychol. 2018;127:417–428.
6. Sabel BA, et al. Mental stress as consequence and cause of vision loss: the dawn of psychosomatic ophthalmology for preventative and personalized medicine. EPMA Journal. 2018;9:133–160.

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