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Laboratory Sciences
February 2000

Tear Production After Unilateral Removal of the Main Lacrimal Gland in Squirrel Monkeys

Author Affiliations

From the Department of Ophthalmology, Lions Eye Research Laboratories, Laboratory for the Molecular Biology of the Ocular Surface, LSU Eye Center, Louisiana State University Health Sciences Center, New Orleans (Drs Maitchouk, Beuerman, Ohta, and Varnell); and Allergan Pharmaceuticals, Irvine, Calif (Dr Stern). None of the authors has any financial or proprietary interests in any of the products or instruments used in this study.

Arch Ophthalmol. 2000;118(2):246-252. doi:10.1001/archopht.118.2.246

Objective  To study the effects of lacrimal gland removal on basal and reflex tear production and on the ocular surface in the squirrel monkey.

Methods  Unilateral main lacrimal gland removal in 6 squirrel monkeys was followed by Schirmer testing, slitlamp examination with fluorescein, and collection of basal and reflex (stimulated) tears for analysis of tear protein spectra between 0 and 20 kd, as well as histological evaluation.

Results  Schirmer test results showed an 80% decrease in basal tears and a 90% decrease in reflex tears during week 1, and a 32.2% and 33.3% decrease, respectively, at week 20 after surgery, compared with the contralateral control side. However, no gross abnormalities or fluorescein staining were seen in 5 of the 6 monkeys, and the conjunctival surfaces remained normal. The main and accessory lacrimal glands appeared to secrete similar types of proteins. No histological changes were seen in corneal, conjunctival, or eyelid tissues 20 weeks after surgery.

Conclusions  Tears from accessory lacrimal glands were sufficient to maintain a stable tear layer on the cornea, suggesting that so-called basal tear flow is made up of fluid from both main and accessory lacrimal glands and that decreased tear production by the main lacrimal gland is not a causative factor in keratoconjunctivitis sicca.

Clinical Relevance  This study shows that total removal of the main lacrimal gland does not in itself lead to keratoconjunctivitis sicca. However, the nature of neural control of the accessory glands is not yet clear.