Dry Eye Diagnosis
Diagnosis tests and procedures used to determine the cause of your dry eyes include:
- A comprehensive eye exam - An eye exam that includes a complete history of your overall health and your eye health can help your doctor diagnose the cause of your dry eyes.
- By measuring the volume of your tears, the dry eye diagnosis can be done. The doctor may measure your tear production using the Schirmer test. In this test, blotting strips of paper are placed under your lower eyelids. After five minutes your doctor measures the amount of strip soaked by your tears.
- Determining the quality of your tears - Other tests use special dyes in eyedrops to determine the surface condition of your eyes. Your doctor looks for staining patterns on the corneas and measures how long it takes before your tears evaporate.
- Schirmer Test - The Schirmer test measures total tear secretion, including reflex and basal tears. Schirmer strips are inserted into the conjunctiva, and the length of wetting strips is recorded after 5 minutes. Another variation of this test, which uses anesthesia and only measures reflex tears using stimulation with a cotton tip applicator. The Schirmer test is more reproducible in more advanced cases of dry eye disease. Although the Schirmer test is one of the most widely used tools in diagnosing dry eye, the lengthy nature of the test, the fact that most patients find the test irritating and invasive, and its unreliable and largely irreproducible nature may explain a high risk of underdiagnosis.
- Fluorescein Staining - Fluorescein sodium can be used to identify layer defects and can be a useful tool in evaluating dry eye. The surface of cornea will stain whenever there is a disruption of cell-to-cell junctions. The staining can show corneal layers puncture epithelial jerks in patterns that are certain causes of dry eye.
- Rose Bengal Staining - Rose bengal staining occurs in areas on the cornea or conjunctiva that lack mucins. RB is an important tool in evaluating dry eye, but it is best used as an supplement due to its lack of sensitivity and specificity. RB without concurrent anesthesia can cause discomfort upon instillation and is therefore less commonly used than fluorescein.
- Lissamine Green Staining - Lissamine green (LG) is another dye similar to RB that stains the ocular surface of the eye. Both types of dyes have similar staining patterns and can be interchangeable. But unlike RB, LG is not toxic to the corneal epithelium, and is better tolerated.
- Tear Function Index - The tear function index is another method of analyzing tear production and is similar to the anesthetized Schirmer test. Five minutes after instilling a 10 μL drop of fluorescein, the length of the wetted area is measured and its intensity is compared with a standard color strip. The tear clearance rate is based on the rate at which the color of the fluorescein dye fades.
- Tear Break-up Time - The tear break-up time (TBUT) measures stability of the tear film. With fluorescein instilled, TBUT is the time interval after a patient blinks to the first appearance of dryness in the tear film. A patient is asked not to blink after instillation of fluorescein. The patient has dry eye if a dry area appears before 10 seconds.
- Functional Visual Acuity - A common complaint of patients who have dry eye is decreased visual acuity. Activities that require concentration, such as reading, driving, and computer work, cause the blinking rate to be decreased. Patients who have an unstable tear film can show decreased visual acuity especially at these times of prolonged concentration. Functional visual acuity reflects performance in relation to specific daily activities involving visual tasks. Eyes can become drier when normal blinking is suppressed during gazing activities.
Conclusion
As the dry eye basically depends on the problem of tears and its volume, so the dry eye syndrome can be diagnosed by various tests and procedures which somehow measures the volume and determines the quality of you tears. The various tests such as Schirmer test, Fluorescein sodium test, Lissamine green staining, Tear function index and functional visual activity.