The superior lacrimal gland (SLG) is an exocrine gland responsible for secreting lacrimal fluid, which lubricates and protects the eye. This article details the surgical techniques for excising both the orbital and palpebral parts of the SLG in a rabbit model.
The superior lacrimal gland or SLG is an exocrine gland located above the eyeball in the lacrimal fossa - a cavity in the frontal bone. This gland secretes lacrimal fluid, which lubricates and protects the eye from bacterial infections.
This gland consists of two connected components; the larger orbital part or OSLG is located lateral to the skull's midline, while the smaller palpebral part or PSLG is present above the upper eyelid. To excise SLGs, take an anesthetized rabbit and prep it by shaving its fur on the head.
Locate a site near the midline of the skull and infiltrate it with local anesthesia. Use a specialized electrosurgery needle that uses electric current-induced burning to incise the skin and muscle layers while controlling bleeding by coagulation. Retract the overlaying muscles to visualize the OSLG. Apply pressure to elevate the gland from the incision site.
Cauterize with the electrosurgery needle to truncate the gland at the incision site. For harvesting PSLG, evert the upper eyelid to locate the bulbous portion of the gland. Sever the connections of PSLG from the tarsus muscle of the eyelid removing the gland from the eye. Store both the compartments of the superior lacrimal glands till further use.
To remove the orbital superior lacrimal gland, or OSLG, infiltrate the incision sites with a 50:50 mixture of 2% lidocaine and 1:100,000 epinephrine with 0.5% bupivacaine. Then, use a Colorado needle connected to an electrosurgical unit to make the skin incisions along the surgical markings. Typical settings are between 10 and 15 units for both cut and coagulation, but can vary depending on clinical response. Apply opposing tension across the skin incision to separate the tissues and expose the underlying frontoscutularis muscle fibers.
Then, apply medial pressure on the globe to aid visualization of the OSLG, which is seen as bulging tissue located just medial or deep to the frontoscutularis muscle fibers. If necessary, move the muscle fibers to the side to expose the underlying incisure, and use toothed forceps with capsulotomy scissors to gently retract and cut the fibrous capsule over the OSLG.
Using forceps, grasp the OSLG gland tissue and gently pull it through the superior incisure using a hand-over-hand technique. Cut small fibrous bands with the capsulotomy scissors to free the gland from its position in the orbit. When the gland has been removed, use generous cautery with the Colorado needle to create tissue char, truncating the gland within the incisure as deeply as possible. This will later serve as a confirmatory landmark during the removal of the palpebral superior lacrimal gland, or PSLG.
To remove the PSLG, evert the upper eyelid with a cotton-tipped applicator, which will make the bulbous end of the PSLG visible. Engage the PSLG with toothed forceps, and retract it from the eyelid surface while using capsulotomy scissors to cut around its base, and separate it from the underlying tarsus. Control moderate bleeding with the monopolar cautery. Apply continuous traction on the separated tissue plane for dissection, which will allow the main excretory duct of the superior lacrimal gland, or SLG, to be removed as well.
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