Abstract
Two-photon (2P) microscopy is a powerful tool for imaging and exploring label-free biological tissues at high resolution. Although this type of microscopy has been demonstrated in ex vivo ocular tissues of both humans and animal models, imaging the human eye in vivo has always been challenging. This work presents a novel compact 2P microscope for non-contact imaging of the anterior part of the living human eye. The performance of the instrument was tested and the maximum permissible exposure to protect ocular tissues established. To the best of our knowledge, 2P images of the in vivo human cornea, the sclera and the trabecular meshwork are shown for the very first time. Acquired images are of enough quality to visualize collagen arrangement and morphological features of clinical interest. Future implementations of this technique may constitute a potential tool for early diagnosis of ocular diseases at submicron scale.
Highlights
The eye is the sense organ responsible for vision
This might cause thermal damage in the tissues when the laser power density is above the maximum permissible exposure (MPE) for a given exposure time
To the best of our knowledge, we have demonstrated 2P imaging in the intact human eye for the first time
Summary
Among its physiological complex elements, two of them are rich in collagen: the cornea and the sclera The former is transparent and contributes to approximately two-thirds of the eye’s refractive power[1]. Different clinical instruments are used to image corneal structures These include specular microscopy (or reflectance confocal microscopy) and optical coherence tomography (OCT)[2,3]. Stromal structure can be imaged with OCT, but micrometric resolution is not achievable These constraints have been overpassed by using two-photon (2P) microscopy[4]. Its capability to image the eye’s structures with sub-micron resolution provide potential advantages compared to other “classical” clinical imaging techniques, such as OCT, fluorescence microscopy or confocal reflectance. Much effort and interest were put on the cornea since www.nature.com/scientificreports/
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