Diagnostic tests in dry eye

ABSTRACT

Introduction: Dry Eye (DE) is a multifactorial condition with a variable clinical presentation. This highly prevalent disease has multiple symptoms and signs that often do not correlate with one another. As such, the diagnosis of DE can be challenging to make, and a systematic approach must be taken.

Areas covered: We review the different methods commonly utilized to evaluate a patient complaining of DE symptoms. Included in this review are clinical examination techniques, point of care tests, and imaging techniques.

Expert opinion: DE is an umbrella term that encompasses different etiologies and pathophysiological mechanisms. The current definition recognizes tear instability, high osmolarity, inflammation, and neuro-sensory dysfunction as causative entities. The approach to DE begins with a systematic assessment of symptoms and signs, evaluating for both nociceptive and neuropathic sources of symptoms. Future research is needed to develop tests that assess neurosensory status in DE and couple point of care tests with therapeutic algorithms.

KEYWORDS:

• Aqueous tear deficiency
• corneal imaging techniques
• corneal stains
• dry eye
• evaporative deficiency
• inflammatory biomarkers
• meibomian gland dysfunction
• neuropathic
• nociceptive
• point of care tests

Article highlights

• The definition of dry eye (DE) encompasses multiple etiologies and pathophysiologies that lead to variable clinical manifestations.

• Diagnosing DE can be challenging, and a systematic approach is needed that includes a medical and ocular history, symptom severity questionnaires, and a slit lamp examination. Point of care tests and imaging techniques can be used to supplement the clinical evaluation.

• The slit lamp examination starts externally by inspecting the facial skin, eyelashes, and eyelids and then moves inward to evaluate the tear film, conjunctiva and cornea.

• Corneal stains assist in the evaluation of the ocular surface.

• Point of care tests include tear osmolarity and inflammatory biomarkers (matrix metalloproteinase-9 and lactoferrin) and can help identify contributing mechanisms in DE.

• Different imaging techniques are available to assess various aspects of the ocular surface including lipid layer thickness, meibomian gland anatomy, and corneal nerve morphology.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

A reviewer on this manuscript has disclosed that they were part of a team which developed the TearLab osmometer, however, they are no longer financially attached to the company and only possess a small amount of company stock. Peer reviewers on this manuscript have no other relevant financial relationships or otherwise to disclose.

Additional information

Funding

This paper was supported by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Clinical Sciences Research EPID-006-15S (A Galor), R01EY026174 (A Galor), NIH Center Core Grant P30EY014801 and Research to Prevent Blindness Unrestricted Grant.