New Microscopy Technique Successfully Images Conjunctival Goblet Cells

Researchers in South Korea have developed a high-performance and non-invasive microscopy system to examine cells involved in protecting the ocular surface.

Conjunctival goblet cells (CGCs) secrete mucins that form a protective mucus layer that spreads tear film on the ocular surface. Dysfunction and death of CGCs causes tear film instability and is associated with various ocular surface diseases including dry eye disease (DED). The ability to examine CGCs would help in diagnosis and effective treatment of ocular surface diseases, but a non-invasive device for such a test has not been available.

Research in 2019 discovered that moxifloxacin, an FDA-approved ophthalmic antibiotic, stains CGCs and demonstrated high-contrast CGC imaging by using moxifloxacin as a cell labeling agent. However, CGC imaging in humans was impossible due to various limitations of conventional microscopy techniques such as shallow depth-of-fields (DOFs) and slow imaging speeds.

A team at Pohang University of Science and Technology (POSTECH) has successfully overcome these limitations. They developed a high-speed extended DOF microscopy method that had a 1 mm DOF (25x DOF extension) and 10 frames per second imaging speed. A deformable mirror axially sweeps the imaging plane and captures CGCs on the arbitrary tilted conjunctiva in single frames.

The acquired images contained both in-focus and out-of-focus information, and the deconvolution was used to filter the in-focus information only. Using the new system, the researchers were able to demonstrate real-time, large-area CGC imaging in live mouse and rabbit models. Their findings are reported in IEEE Transactions on Medical Imaging.

“The newly developed imaging system can obtain high-resolution in-focus images of CGCs in live animal models and is also applicable to humans,” says POSTECH professor Ki Hean Kim . “Going forward, we will develop a device for imaging patients and then run clinical trials to test the feasibility of non-invasive CGC examination in the diagnosis and treatment of ocular surface diseases.”