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. 2025 May;69(3):460-468.
doi: 10.1007/s10384-024-01151-6. Epub 2025 Jan 18.

Visualization of porcine and human aqueous humor outflow tract anatomies with transparency enhancement

Yuichi Asahina  1 , Makoto Aihara  2 , Takashi Miyai  2 , Asami Tanaka  3 , Hiroshi Onodera  4
Affiliations

Visualization of porcine and human aqueous humor outflow tract anatomies with transparency enhancement

Yuichi Asahina et al. Jpn J Ophthalmol. 2025 May.

Abstract

Purpose: There is no established method for visualizing the three-dimensional (3D) structure of the aqueous humor outflow tract. This study attempted to visualize the 3D structures of porcine and human ocular tissues, particularly the aqueous humor outflow tract using a transparency reagent composed of 2, 2-thiodiethanol.

Study design: Clinical and experimental.

Methods: The porcine eyes were collected in Japan, and the human eyes were imported from the United States. The human eyes were obtained from a 64-year-old Caucasian woman, arriving 7 days after her death. The specimens were formalin-fixed upon arrival, fluorescently labeled, optically cleared using a transparency-enhancing reagent, and visualized using a confocal microscope.

Results: Both porcine and human eyes were visualized to the extent that the choroidal vessels were observed on gross examination. The aqueous humor outflow tract was clearly observed as a luminal structure in the porcine eye, mainly depicted by autofluorescence, and in the human eyes as a luminal structure continuing from the trabecular meshwork without fluorescence.

Conclusion: Observations using transparency-enhancing technology enabled us to obtain 3D images useful for visualizing ocular tissues, especially the aqueous humor outflow tract.

Keywords: Aqueous humor outflow tract; Three-dimensional imaging; Transparency enhancement.

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Conflict of interest statement

Declarations. Conflict of interest: Y. Asahina, None; M. Aihara, None; T. Miyai, None; A. Tanaka, None; H. Onodera, None.

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