Dry Eyes - TESTS to Evaluate??!
Question:
Dry Eyes - TESTS to Evaluate??
I have read there are some type of diagnostic tests to evaluatie if you have the condition of "dry eye". I'd appreciate any information on this.
Answers:
Well really there are a few different tests..
1) Schirmer test without anesthesia- test is done by placing strips of special paper on the lower conjunctiva and measuring the amount of paper moistened in 5 minutes. (Less then 10mm of wetting without anesthesia is considered abnormal)
2) Tear Break Up Time- Useful to estimate the mucin content of tear fluid. This test is done by applying a slightly moistened fluorescein strip to the eye. Viewed through a slit lamp (cobalt blue illumination) the patient is asked to blink and the amount of time it takes for a dry spot to appear is the "tear break up time" or TBUT. Normal break up time is over 15 seconds.
3) Ocular ferning test- Drying conjunctival scrapings on a clean glass slide. Microscopic aborization is observed (ferning) is observed in normal eyes
4) Impression Cytology- is a method in which the goblet cell densities on the conjunctival surface are counted. In a normal person the goblet cell population is the highest in the infranasal quadrant.
5) Fluroscein Staining- Touching the conjunctiva with a dry strip of fluorescein is a good indicator of wetness, and the tear meniscus can be seen easily. Fluorescein will stain the eroded and denuded areas as well as microscopic defects of the corneal epithelium
6) Rose Bengal Staining- More sensitive then fluorescein. This will stain all desiccated non vital epithelial cells of the cornea as well as the conjunctiva
7) Tear Lysozyme- Tears are collected on Schirmer strips and assayed
8) Tear film osmolality- Hyperosmolality of tears has been documented in dry eyes. It can occur with a normal Schirmer test and normal rose bengal staining
9) Tear lactoferrin- Tear fluid lactoferrin is low in patients with hyposecretions of the lacrimal gland. Testing kits are commercially available
Depending on the doctor and the suspected cause of your dry eyes they may use one or a combination of these diagnostic tests for dry eyes (keratoconjunctivitis sicca)
EDIT** that video that princeidoc posted of TBUT is a great demonstration of how the process works... I would agree that it is the most commonly used test