In office testing for external disease: Dry eye, adenoviral infection

From EyeWiki
Original article contributed by: Erica Bernfeld M.D.
All contributors: Brad H. Feldman, M.D., Erica Bernfeld M.D., Maria A. Woodward, MD and Vatinee Bunya, MD
Assigned editor:
Review: Assigned status Up to Date by Vatinee Bunya on October 13, 2017.


Various diagnostic tests for signs associated with Dry Eye Disease include: ocular staining, tear break-up time (TBUT), tear osmolarity, Schirmer's Test and Meibomian grading. [1] Additional tests for tear inflammatory biomarkers or systemic diseases like Sjögren’s syndrome may be also helpful in early detection.

Diagnostic Tests:

  1. Corneal and Conjunctival Staining: This is often part of a routine eye exam. The ocular surface is most commonly stained with fluorescein dye. The fluorescein is applied on a moistened sterile strip of paper to the inner lining of the lower eyelid or applied in an eye drop mixed with a topical anesthetic. The ophthalmic strips might be mildly irritating and the drop may briefly burn. When abnormal or missing epithelial cells are stained with fluorescein and observed under a blue light, they appear bright green. Bright green areas of the cornea may indicate dry eye as well as other conditions. Other less commonly utilized stains are lissamine green and rose bengal. Lissamine green and rose bengal have similar staining characteristics for evaluating the conjunctiva. Lissamine green is less toxic and better tolerated than rose bengal.
  2. Tear break-up time (TBUT): The TBUT test is easily and quickly performed after fluorescein is instilled as described above. After the fluorescein is instilled, the patient is asked to stare without blinking. The cornea is observed under a blue light and time is counted in seconds, from the time of the last blink until a pocket of cornea appears that is no longer covered with fluorescein stained tears. The longer the TBUT, the more stable the tear film. A TBUT > 8-10 seconds is usually considered normal. 5-10 seconds is borderline and < 5 seconds suggests an unstable tear film and "dry" eye.
  3. Schirmer's Test: To perform the anesthetized Schirmer's test, a small paper strip with rulers printed along their length are placed inside the lower eyelids (inside the inferior conjunctival fornices) after the eyes are numbed with a topical anesthetic drop. The strips are removed after 5 minutes and the amount of tears produced in that time is read off of the strips (and measured in millimeters). Interpretations can vary but usually < 10mm of tear production in 5 minutes is suggestive of some form of dry eye. Of note, the Schirmer's test can also be performed without anesthesia. The unanesthetized Schirmer's test is required when evaluating a patient for possible Sjogren's syndrome.
  4. TearLab: This in office test measures tear osmolarity. The test is a relatively painless and quick (seconds) and can be performed by an ophthalmic technician. Increased osmolarity indicates dry eye. A score over 300 mOsm/L or an intereye difference greater than 8 mOsm/L indicates dry eye. [2]
  5. LipiView: An interferometer is a noninvasive instrument that measures the amount of oil in the tear film. The measurements are obtained through images of the tear film that are captured over a 5 minute period. [3]
  6. Sjo®: Diagnostic testing panel for detection of novel and classic protein, antibody and factor biomarkers associated with early symptoms of Sjögren’s syndrome which can present as dry eye. Finger prick blood sample is collected to saturate 18 3mm punches on specimen filter paper and sent to the lab. It is important to note that a positive Sjo test does not necessarily mean that a patient has Sjogren's syndrome. Patients with a positive Sjo test should be referred to a rheumatologist for a full Sjogren's syndrome work-up. [4]
  7. InflammaDry® - A rapid 4 step test that measures the inflammatory marker, MMP-9 found to be elevated in tears of patients with dry eye. Test is performed prior to other tear testing, instillation of ocular anesthesia or topical dyes. A tear sample is collected from the palpebral conjunctiva and combined with test buffer. Color coded results are read after 10 minutes. It is important to be aware that the test can be falsely positive in certain settings such as allergic conjunctivitis and infection. [5]

References

  1. Am J Ophthalmol. 2011 May;151(5):792-798.e1. doi: 10.1016/j.ajo.2010.10.032. Epub 2011 Feb 18. "Tear Osmolarity in the diagnosis and management of dry eye disease." Lemp MA1, Bron AJ, Baudouin C, Benítez Del Castillo JM, Geffen D, Tauber J, Foulks GN, Pepose JS, Sullivan BD.
  2. TearLab. https://www.tearlab.com/ Accessed October 9, 2017.
  3. TearScience System with LipiView® / Lipiflow®. http://tearscience.com/en/ Accessed October 9, 2017.
  4. http://www.bausch.com/ecp/our-products/diagnostics/sjo Accessed October 9, 2017.
  5. InflammaDry®. A Simple 4-Step Process to Aid in Dry Eye Diagnosis. https://www.quidel.com/immunoassays/inflammadry https://www.quidel.com/sites/default/files/product/documents/HT1024000EN01.pdf Accessed October 9, 2017.