Clinical Trial: Visual Activity Evoked by Infrared in Humans After Dark Adaptation
Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title: Visual Activity Evoked by Infrared in Humans After Dark Adaptation
Brief Summary:
This pilot study will evaluate the visual response to infrared (IR) in humans after dark adaptation. The investigators plan to determine which wavelength and intensity the human eye is most sensitive too, using a broad spectrum light source and wavelength-specific bandpass filters. The investigators will then evaluate the electrophysiologic response in healthy humans to IR, followed by studies in those with specific retinal diseases.
The long-term goal of this research is to better understand the role that IR plays in visual function, and whether this can be manipulated to allow for vision in certain retinal pathologies that result from loss of photoreceptor cells. The investigators central objective is to test the electrophysiologic response to IR in the dark-adapted retinal and visual pathways. The investigators central hypothesis is that IR evokes a visual response in humans after dark adaptation, and the characteristics of this response suggest transient receptor potential (TRP) channel involvement. The investigators rationale is that a better understanding of how IR impacts vision may allow for an alternative mechanism for vision in a number of diseases that cause blindness from the degradation or loss of function of photoreceptor cells. The investigators will test the investigators hypothesis with the following Aims:
Aim 1: To determine the optimal IR wavelength for visual perception in dark-adapted human participants. The investigators hypothesize that the healthy human eye will detect IR irradiation, with a maximum sensitivity at a specific wavelength. Using a broad-spectrum light source with wavelength-specific bandpass filters, the spectral range of visual perception to IR will be evaluated. The same will be done on colorblind participants.
Aim 2: To test the elec
Detailed Summary:
BACKGROUND: Visual impairment affects 285 million people worldwide. The prevalence of visual impairment in the US is expected to rise from 3.3 million in 2000 to 5.5 million in 2020. This will exacerbate the current economic burden of vision loss, which is already $38.2 billion per year in direct and indirect costs. The leading cause of blindness in high income countries is due to age-related macular degeneration (AMD), a disease that leads to gradual loss of the photoreceptor cell layer. An estimated 1.75 million people have AMD in the US and another 7.3 million are at risk. Importantly, despite the loss of photoreceptor cells in AMD, the other cellular layers in the retina remain largely intact.
The retina lines the back of the eye and is composed of structural layers. The outer nuclear layer contains photoreceptors called rods and cones. The inner nuclear layer includes bipolar, horizontal, and amacrine cells. Most anteriorly, the ganglion cell layer has axons that exit the eye as the optic nerve. Visual image formation begins when a photon of light enters the eye, passes through all retinal layers, and is absorbed by the photoreceptor cells. These cells transduce the photon of light into an electrochemical signal, which is communicated to bipolar cells, followed by the ganglion cells. Here, an action potential is generated and propagated via the optic nerve to the area of the brain where vision perception occurs. When the eye is dark adapted, the cells in this pathway are potentially more sensitive to other types of stimuli, such as IR. The investigators believe cation channels called TRP channels in ganglion cells are activated by IR in this dark adapted state, creating the visual response to IR. Heat is a known activator of certain subtypes these channels elsewhere in the body. TRP channels are also responsible for IR vision in pit vipers and vampire bats.
Sponsor: University of New MexicoCurrent Primary Outcome: Visual perception to infrared [ Time Frame: Up to one year ]
Original Primary Outcome: Same as current
Current Secondary Outcome: Description of color [ Time Frame: Up to one year ]
Original Secondary Outcome: Same as current
Information By: University of New Mexico
Dates:
Date Received: May 6, 2016
Date Started: September 2015
Date Completion:
Last Updated: September 16, 2016
Last Verified: September 2016
