From the Guidelines
Diagnosing dry eye and related conditions involves a comprehensive evaluation, including a thorough medical history, slit-lamp examination, and specialized tests such as the Schirmer test and tear film break-up time assessment 1. The diagnosis of dry eye is typically confirmed by the presence of symptoms, including ocular irritation and blurred vision, in conjunction with objective findings of reduced tear production, often defined as a Schirmer test value of less than 5.5 mm 1.
Diagnostic Tests
- Aqueous tear production (Schirmer test): measures both basic and reflex tearing, with a value of less than 5.5 mm considered diagnostic of aqueous tear deficiency 1
- Fluorescein dye disappearance test/tear function index: compares test results with a standard color scale, with less than 10 seconds considered abnormal 1
- Fluorescein tear break-up time: assesses the stability of the tear film, with a rapid break-up time indicating an unstable tear film 1
- Ocular surface dye staining: indicates decreased tear lactoferrin concentration, with staining of the inferior cornea and bulbar conjunctiva within the palpebral fissure being typical 1
- Tear osmolarity: indicates the presence of inflammation, with a cutoff of 312 mOsms/L having 73% sensitivity and 92% specificity for diagnosing dry eye 1
- Matrix metalloproteinase-9: a point-of-care test that can aid in the diagnosis of dry eye, although it does not differentiate dry eye from other inflammatory ocular surface diseases 1
Classification of Dry Eye Disease
Dry eye disease can be classified into mild, moderate, and severe based on symptoms and signs, with an emphasis on symptoms over signs 1. It can also be categorized into aqueous tear deficiency and evaporative forms, with the majority of patients having a combination of both 1.
Treatment
Treatment may involve the use of artificial tears, such as preservative-free sodium hyaluronate 0.1% or carboxymethylcellulose 0.5%, administered 2-4 times daily, and in severe cases, may require the addition of anti-inflammatory medications, such as loteprednol etabonate 0.5% ophthalmic suspension, dosed 2-4 times daily for a duration of 2-4 weeks 1.
Special Considerations
Patients with dry eye syndrome considering keratorefractive and lens-based surgery should be cautioned that the dry eye symptoms could become worse after surgery, and pre-existing factors contributing to dry eye syndrome should be improved preoperatively to reduce the chance of worsened dry eye syndrome 1. Approximately 10% of patients with clinically aqueous tear deficiency dry eye have underlying Sjögren’s syndrome, which should be suspected if intrinsic tear-production deficiency is detected in nonelderly women, especially if it is rapid in onset and/or marked in severity 1.
From the Research
Diagnostic Methods for Dry Eye
- Slit-lamp-based techniques, such as direct palpebral lobe and tear flow assessment, Schirmer test, meibum quality and expressibility, and evaluation of tear meniscus height, can be used to diagnose dry eye disease (DED) 2
- Non-invasive tear meniscus height (TMH), tear break-up time (TBUT), lipid layer thickness (LLT), and meibography are machine-based diagnostic tests that can be used to evaluate DED 2
- The recommended sequence of tests for diagnosing DED is a dry eye questionnaire, TMH, LLT, NIBUT (FBUT if non-invasive test is unavailable but should be performed after osmolarity), tear osmolarity, meibography, and ocular surface staining 2
- Blinking tolerance time (BTT) is a new diagnostic test that can be used for self-evaluation of tear-film stability, and it has been validated against the tBUT test 3
Evaluation of Tear-Producing Glands
- The structure-function correlation of the tear-producing glands gives more comprehensive details than either information alone 2
- Meibography can be used to evaluate the meibomian glands, and it is a non-invasive diagnostic test 2
- Schirmer test can be used to evaluate the lacrimal gland function, but it is an invasive test and should be performed after non-invasive tear film diagnostic testing 2