Ultrasound-Guided Concanavalin A Injection Into Inferior Lacrimal Gland: A Technique to Inoculate Inferior Lacrimal Gland With Concanavalin A to Induce Dry Eye Disease in Rabbit Model

In rabbits, the inferior lacrimal gland or ILG occupies the inferior-posterior aspect of the orbital margin and aids in tear fluid secretion necessary to maintain a healthy ocular surface. Impaired ILG function can compromise the ocular surface to inflammatory damage, causing dry eye disease or DED.

To create a DED model, first, prep an anesthetized rabbit, removing all the fur from its scalp and the area around the orbit for ultrasound localization of anatomical landmarks. Next, locate a bone projection, the 'ILG head', along the lower orbital margin. The ILG head rests over the zygomatic or cheekbone and extends posteriorly to form the 'ILG tail', occupying a more medial position in the orbit. Mark this region of ILG head-to-tail transition.

Sweep an ultrasound probe across the marking to identify a change from a bright hyperechoic signal representative of zygomatic bone to a 'no bone echo' signal, indicating the transition of ILG head to tail. Now, inject concanavalin A, a T-cell mitogen, at this site, inserting the needle deep enough to inoculate the ILG tail.

Post-injection, repeat the ultrasound. A dark hypoechoic space indicating the presence of fluid confirms successful concanavalin A delivery. Inside the ILG, concanavalin A induces T-cell infiltration and activation, triggering a proinflammatory response that disrupts ILG functioning, reducing tear fluid secretion. Eventually, the ocular surface also suffers damage, leading to DED.