Can declining vision in the elderly be associated with cognitive decline? A recent article in the New York Times reported on a study published in JAMA Open Network indicating just that. The study used data from the Baltimore Longitudinal Study of Aging for 2003 to 2019. The more than 1,200 participants in the study were aged 60 to 94 years. Visual function was evaluated for acuity, contrast sensitivity, and stereo acuity. Cognitive function was evaluated for language, memory, attention, executive function, and visuospatial ability (the ability to identify visual and spatial relationships among objects). All participants had normal cognitive function at the initiation of the study, with standard deviations (SD) in visual acuity of 0.16, and contrast sensitivity of 1.9.
Light, or visible light, is but a small portion of the electromagnetic spectrum that our eyes can detect. The visible light spectrum consists of wavelengths of light (from shortest to longest) violet, indigo, blue, green, yellow, orange, red, and travels from the sun at 186,000/miles per second before it strikes an object. Depending on the object it strikes, it will either absorb, reflect, or refract the light. As an example, let's use a red apple. When sunlight, or white light, strikes the apple, the component colors are broken down and all the wavelengths of light are absorbed with the exception of the red wavelengths; they are being reflected. As our eyes process this information and fine-tune this data, our brain interprets this, and we see that all the colors except red are absorbed by the apple. The red wavelength is reflected, and therefore the apple appears red.
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