CGC examination of live rabbit eyes for improved diagnosis of diseases in ocular surfaces

Chester Mendoza, Clinical Director Ophthalmology, Asklepios

Successfully demonstrating the non-invasive CGC examination in live rabbit eyes. . The researchers have taken a step further in this study by imaging CGCs in live rabbits whose eyes are similar to those of humans.

In collaboration with Professor Chang Ho Yoon (Department of Ophthalmology) of Seoul National University Hospital and Professor Young-Ho Jung (Department of Ophthalmology) of Eulji Hospital, a Korean research team led by Professor Ki Hean Kim, Ph.D. candidates Seonghan Kim and Jungbin Lee (Department of Mechanical Engineering) at POSTECH successfully demonstrated the non-invasive CGC examination in live rabbit eyes.

Goblet cells are specialized epithelial cells in the conjunctiva of the eyes that secrete mucins to form the mucus layer of the tear film. By spreading the tear film, the mucus layer protects the ocular surface. Tear film instability is caused by choroidal ganglion cell(CGC) malfunction and death, which is linked to a variety of ocular surface disorders, including dry eye disease (DED).

As a result, CGC examination is critical for the effective diagnosis and treatment of ocular surface disorders. However, due to a lack of non-invasive devices, it has not been possible until now. The researchers had recently developed non-invasive high-contrast CGC imaging methods that used moxifloxacin, an FDA-approved ocular antibiotic, as a cell labeling agent. The researchers took a step further in this study by imaging CGCs in live rabbits whose eyes are similar to those of humans.

The researchers initially examined normal rabbits to ensure that CGC pictures with the new imaging technology matched those captured with traditional histological photos using periodic-acid Schiff (PAS) staining.The researchers then imaged DED rabbit models. DED was induced with topical instillation of povidone-iodine (brand name: Betadine), a disinfectant used in ophthalmic surgery that is known to cause temporary DED after ophthalmic surgeries.

CGC density decreased in the first and second weeks of DED induction, then recovered to normal in the third and fourth weeks, according to the researchers. The results of standard DED evaluations, such as the corneal staining score, tear volume measurement (Schirmer's test), and tear break-up time measurement, as well as conventional histology with PAS staining, were consistent with the changes in CGC density observed with this technology in live rabbits.

The study's findings were recently published in The Ocular Surface, an ophthalmology journal with a prestigious reputation. This technique is safely used in patients since it uses an FDA-approved antibiotic called moxifloxacin.