Light sensation relies on photoisomerization of chromophores in rod and cone photoreceptor cells. Spectral sensitivity of these photoreceptor cells in the retina is determined by the absorption spectra of their pigments which covers a range from 400 nm to above 700 nm. Regardless the mechanism leading to visual pigment isomerization, light sensation is triggered every time visual pigment molecules change their conformation. Thus, two-photon absorption (TPA) should produce the same result (visual sensation) as single photon absorption of light. This observation was positively verified and published by our group. During human psychophysics experiments, we found that humans can perceive light in the infrared (IR) range as colors that match half of the wavelength of the applied laser beam. Other experiments and theoretical research, such as mouse electrophysiology, biochemical studies of TPA in rhodopsin or molecular modeling studies, confirmed that visual sensation can be triggered by TPA. There are few publications describing human near infrared (NIR) perception and no formal proposals to use this phenomenon to improve ophthalmic diagnosis and monitor treatment. Here we report that the use of novel instrumentation revealed that the sensitivity threshold for NIR vision depends on age.
Maciej Wojtkowski, Katarzyna Komar, Grazyna Palczewska, Agnieszka Zielinska, Patrycjusz Stremplewski, and Krzysztof Palczewski, "Age dependent sensitivity of two-photon isomerization of rhodopsin chromophores in the human retina
(Conference Presentation)," Proc. SPIE 9693, Ophthalmic Technologies XXVI, 969312 (Presented at SPIE BiOS: February 14, 2016; Published: 26 April 2016); https://doi.org/10.1117/12.2211643.4848636519001.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the proceedings. They include the speaker's narration with video of the slides and animations. Most include full-text papers. Interactive, searchable transcripts and closed captioning are now available for most presentations.
Search our growing collection of more than 29,500 conference presentations, including many plenaries and keynotes.