Original articleDiagnosis of Dry Eye
Section snippets
Symptom Questionnaires
Schein and colleagues27, 28 developed and validated a dry eye symptom questionnaire for a large population study in Maryland, USA.3 The questionnaire consisted of questions relating to six symptoms:
- 1.
Do your eyes ever feel dry?
- 2.
Do you ever have a gritty or sandy sensation in your eyes?
- 3.
Do your eyes ever have a burning sensation?
- 4.
Are your eyes ever red?
- 5.
Do you notice much crusting on your lashes?
- 6.
Do your eyes ever get stuck shut in the morning?
Patients who indicated the presence of a symptom were asked
Ocular Surface Staining
Epithelial damage to the exposed surface of the eye can be demonstrated with vital and supra-vital stains. Staining of the cornea occurs preferentially over its lower part, often more nasally than temporally and frequently in continuity with the bulbar conjunctival stain. Staining of the bulbar conjunctiva occurs over a wedge-shaped zone nasally and temporally, and in advanced dry eye may become confluent. Staining on the conjunctiva may be present in the absence of corneal stain, in milder
Fluorescein tear break-up test (but)
The tear break-up test is the standard clinic test for estimating tear film stability.18, 25 It is a provocative test in the sense that the instillation of fluorescein shortens the normal break-up time.22 Break-up is best observed with use of a blue exciter and yellow barrier filter, while the patient refrains from blinking. The yellow filter, however, is not essential. The break-up time is the time that elapses from the last blink to the first appearance of a dark spot in the
Assessment of Tear Osmolarity
Considerable evidence suggests that tear hyperosmolarity is a primary mechanism for ocular surface damage in all forms of dry eye.10, 11 In the rabbit, deficiency of the aqueous or lipid layer of the tear film results in a rise in tear osmolarity and associated squamous metaplasia and loss of goblet cells.12, 13
To assess tear osmolarity clinically, nanolitre samples are taken from the lower tear meniscus and measured with a Clifton depression of freezing point osmometer or an Advanced
Tear Turnover
Studies by Pflugfelder et al 26 have shown that tear turnover is reduced in various forms of dry eye. This can be assessed using the fluorescein clearance test. A standard Schirmer strip is placed over the lateral lower lid margin for a period of 1 minute at 10, 20, and 30 minutes after instillation of 5 μl of sterile fluorescein into the conjunctival sac. After removal, each strip is examined under a blue light for the presence or absence of fluorescein. In these studies, in all normal
Characterizing Dry Eye Disease
The classification of dry eye disease into tear-deficient or evaporative dry eye requires further diagnostic tests. Several tests are available in the clinic to demonstrate reduced tear flow or volume.
Sequence of Testing
The diagnosis of dry eye depends on the results of several of the above tests, which ideally could be performed at a single clinic visit. It is important, therefore, to carry out the tests in an appropriate order, to avoid one test interfering with another. Table 1 suggests a suitable order of diagnostic tests, although there are no formal data to justify a particular sequence of tests or the intervals between them. Not all tests will be available in every clinic and some of the tests listed
Acknowledgements
The author is a consultant to Allergan, Ltd., and co-inventor of the Meniscometry technique.
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