In situ Observations of Porcine Ocular Surface Cells with Handheld 2K-pixel Microscope

Tatsuya Mimura1, *, Atsushi Mizota1, Toshihiro Hayashi2, Satoshi Nishimura3
1 Department of Ophthalmology, School of Medicine, Teikyo University, Tokyo, Japan
2 Department of Physiology, School of Medicine, Teikyo University, Tokyo, Japan
3 Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan.

© 2020 Mimura et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: Address correspondence to this author at Department of Ophthalmology, School of Medicine, Teikyo University, Tokyo, Japan; Tel: +81-3-3964-1211; Fax: +81-3-3964-1402; E-mail:



To present our findings of the porcine ocular surface that were obtained with an ultra-compact hand-held microscope that weighs less than 500 g, we examined the corneal epithelial cells with this hand-held microscope.


This device is equipped with an automatic focusing mechanism that enabled us to observe living cells in macro to micro magnifications with a series of operations. The focus is semi-automatically adjusted by the infrared and ultrasonic distance sensor. The instrument has a commercially-available microscope objective lens of 20x or 40x magnification and has a high-resolution 2K Complementary Metal-Oxide-Semiconductor (CMOS) camera. The theoretical spatial resolution is around 300 nm with a higher Numerical Aperture (high-NA) lenses. The widefield reflectance-based imaging system is equipped with three-color visible Light-Emitting Diodes (LEDs) for use in bright environments and an infrared LED for dark environments. Ten normal and two injured porcine corneas were examined with this hand-held microscope.


Our observations showed that the corneal and conjunctival epithelial cells could be continuously observed. The epithelial cells of the central cornea, limbus, and conjunctiva were clearly seen. The epithelial cells on the injured corneal surface were also easily and clearly observed.


This hand-held microscopic imaging device allows medical health care workers such as ophthalmologists and endoscopists to obtain real-time in vivo optical biopsies without collecting tissues and cells. Our system enables us to observe single cells in the superficial layers without any fluorescein or other dyes.

Keywords : Eye, Handheld microscope, In situ observation, In vivo imaging, Ocular surface, Porcine.