Imaging Studies
CT scan of the orbits - Aplastic/hypoplastic lacrimal glands
Procedures
Neostigmine testing
Neostigmine testing can be performed as a challenge to evaluate for the presence of secondary tear production.
Dosages vary but can be calculated with this formula: [Weight (kg)/70] X 1.5 mg = dose
The patient may be reexamined 30-45 minutes later for evidence of tear production. Typically, no secondary tear production is seen in patients with alacrima.
Schirmer testing
This secretory test is used in the evaluation of patients with alacrima. Testing can be performed to test for basal secretors or for combined basal and reflex secretors. Schirmer test strips are specially prepared Whatman #41 paper, each measuring 35 mm in length and 5 mm in width. A notch is located 5 mm from the end to facilitate bending and placement in the conjunctival fornix. After placement in the fornix, tears advance via capillarity and reflect the tear production of the eye.
For basal secretor testing, a drop of topical anesthetic is placed in the conjunctival fornix. The inferior fornix should be dried with a cotton-tipped applicator. The Schirmer test strip is bent at the 5 mm notch and placed in the central lid of each eye. The strips are removed at 5 minutes, and a pen mark is placed at the junction of the wet test strip and the dry test strip. A measurement is made between the mark and the 5 mm notch. A normal value is 10 mm of wetting at 5 minutes, with lower values indicating a dry eye condition. Of asymptomatic patients, 15% have values of less than 3 mm.
For basal and reflex secretor testing, no topical anesthetic is used. The inferior fornix should be dried with a cotton-tipped applicator. The test is carried out as outlined above, and the normal median wetting approximates 15 mm, with a range of 10-30 mm. A value of less than 5 mm is abnormally low.
Conjunctival and lacrimal gland biopsy
Conjunctival and lacrimal gland biopsy specimens may be of value to identify underlying histopathologic findings.
Histologic Findings
Conjunctiva biopsy specimens reveal hydropic epithelial degeneration. Lacrimal gland biopsy specimens may reveal neuronal degeneration and depletion of dense core vesicles.
