Periodic Reporting for period 1 - TrackCycle.2P (Exploring Visual Processes with Two-Photon Ophthalmoscopy)
Reporting period: 2020-02-01 to 2021-07-31
Many retinal diseases that lead to blindness, such as age-related macular degeneration or the genetic disease retinitis pigmentosa, can only be detected at a late stage or with genetic testing. So far, there are hardly any imaging methods for early objective diagnosis. Pathological changes in the retina affect the visual cycle that is initiated at the visual pigment in the photoreceptors of the retina: the visual pigment captures photons of light and subsequently changes to an excited state. This triggers the conversion of the light energy into an electrical impulse, which is transmitted to the brain via the optic nerve and produces the actual visual impression. The visual pigment is then regenerated and can absorb photons again.
It is this process that will be studied with two-photon ophthalmoscopy, a highly accurate method for examining the fundus of the eye. We will establish the measurement method and advance it for application to the human eye. Ultra-short laser pulses are used to cast light onto the retina and measure the visual cycle with a special ophthalmoscope. This is done by taking advantage of the fact that during the course of the visual cycle a molecule is produced, which can be excited to fluoresce.
A major goal of this project is to measure the strength of the fluorescent light in both types of photoreceptors in the retina, the rods and cones, in subjects with healthy eyes in order to learn more about the kinetics of the visual cycles in the normal range. The measurements should enable the detection of attenuations or slowdowns of the visual cycle in the event of a pathological change in the retina. Moreover, the visual experience in people exposed to two-photon ophthalmoscopy will be investigated. This will allow a better insight into the first steps of vision.
Successful implementation of two-photon ophthalmoscopy and application to the human eye promises to broaden our knowledge of normal and abnormal visual cycle function and further our understanding of retinal biochemistry in health and disease.