Microperimetry is a subjective visual field testing method that enables the assessment of retinal function at various specific and focal locations. Two-photon microperimetry is an extension of this technique. In contrast to traditional microperimetry, which uses a visible stimulus, two-photon microperimetry utilizes pulsed infrared lasers as a source of stimulating radiation. The subject perceives such a stimulus as a color one due to the two-photon vision phenomenon .
The applicability of two-photon microperimetry depends largely on the parameters of the laser used for experiments. Therefore, in ICTER, we conduct extensive research on the influence of parameters of pulsed infrared laser, like pulse duration, pulse repetition rate, wavelength, on the perception by humans [2, 3]. Moreover, we perform a clinical assessment of two-photon microperimetry usefulness for earlier and more effective eye visual function abnormalities . We hope that a deeper understanding of the phenomenon of two-photon vision, optimization of visual field test procedures, and clinical tests enable us to provide a useful tool for ophthalmologists worldwide.
 Ruminski et al., BOE 10(9), pp. 4551-4567 (2019). DOI: 10.1364/BOE.10.004551
 Marzejon et al., BOE 12(2), pp. 462-479 (2021). DOI: 10.1364/BOE.411168
 Marzejon et al., Proc. SPIE 11623, 116231N (2021). DOI: 10.1117/12.2582735
 Komar et al., AOVS 62(8), 2009 (2021).
Text: Marcin Marzejon, MSc
Two-photon microperimetry: sensitivity of human photoreceptors to infrared light
Daniel Ruminski, Grazyna Palczewska, Maciej Nowakowski, Agnieszka Zielińska, Vladimir J. Kefalov, Katarzyna Komar, Krzysztof Palczewski, and Maciej Wojtkowski
Microperimetry is a subjective ophthalmologic test used to assess retinal function at various specific and focal locations of the visual field. Historically, visible light has been described as ranging from 400 to 720 nm. However, we previously demonstrated that infra-red light can initiate visual transduction in rod photoreceptors by a mechanism of two-photon absorption by visual pigments. Here we introduce a newly designed and constructed two-photon microperimeter. We provide for the first time evidence of the presence of a nonlinear process occurring in the human retina based on psychophysical tests using newly developed instrumentation. Since infra-red light penetrates the aged front of the eye better than visible light, it has the potential for improved functional diagnostics in patients with age-related visual disorders.
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