Dry eye disease: A review of diagnostic approaches and treatments

Dry eye (DE) is a common ocular disease that results in eye discomfort, visual disturbance and substantially affects the quality of life. It has a multifactorial etiology involving tear film instability, increased osmolarity of the tear film and inflammation of the ocular surface with potential damage to the ocular surface. This review discusses the classification, diagnostic approaches and treatments of DE.

The International Dry Eye WorkShop (DEWS) classifies dry eye mainly into aqueous deficient dry eye (ADDE) and evaporative dry eye (EDE). ADDE is primarily caused by insufficient tear production, while EDE occurs when tear production is normal but excessive evaporation of tear film occurs. Both types can coexist.

Diagnostic Assessment:

Subjective Evaluation: Symptoms and medical history vary greatly. Although questionnaires help, the correlation between symptoms and disease severity is weak, which complicates diagnosis, disease assessment, and treatment evaluation.

Objective Evaluation: There is no gold standard test or established cutoff values. Common diagnostic tests include tear breakup time (TBUT), corneal staining, tear film assessment, conjunctival staining, and Schirmer test. Emerging evaluation techniques include:

Tear Osmolarity: Osmolarity above 308mOsms/l suggests mild dry eye, and above 312mOsms/l suggests moderate to severe dry eye.

Tear Film Stability: TBUT is commonly used; non-invasive tear breakup time (NIBUT) can be measured by corneal topography and interferometry.

Tear Film Particles: Measured by tracking the movement of reflective particles in the tear film to assess tear film spreading and stability.

Corneal Topography: Systems like TMS-116 and high-speed video corneal topography assess corneal surface regularity and tear film stability.

Interferometry: Measures lipid layer thickness and NIBUT.

Wavefront Aberrometry: Assesses visual disturbance caused by tear film instability and disruption.

Functional Vision: Assesses visual acuity under simulated gaze conditions, reflecting actual vision in dry eye patients.

Optical Coherence Tomography (OCT): Measures tear film thickness and parameters, and can also assess meibomian gland structure.

Non-contact Confocal Microscopy: Observes the tear film and helps in imaging.

Meibomian Gland Evaluation: Through slit-lamp, meibography, and other techniques.

Corneal and Conjunctival Staining: Evaluates ocular surface damage but is subjective with poor reproducibility.

Conjunctival Cytology: Provides information on dry eye diagnosis through flow cytometry analysis of cytokines and immune cells.

Treatment:

Anti-inflammatory Treatment: Cyclosporine A reduces ocular surface inflammation and increases tear production but may have side effects. Topical steroids are often combined with Cyclosporine A but have risks like increased intraocular pressure and cataracts. Hormonal therapies like androgen and estrogen can improve tear production. Antibiotics like macrolides and tetracycline derivatives have immunomodulatory effects, particularly for blepharitis and rosacea-related dry eye.

Supplementary Treatments: ω-3 fatty acids, nerve growth factor (NGF), and autologous serum show potential. Acupuncture may affect lacrimal gland function by regulating the autonomic and immune systems, but its effectiveness needs further study.

Surgical Treatment: Punctal plugs are effective for patients not responding to medication, reducing tear drainage. Salivary gland surgeries, such as parotid duct transposition or submandibular gland transplantation, can alleviate symptoms in severe cases. Artificial tear pumps and reservoirs can be used for severe dry eye.

Conclusion: A deeper understanding of the pathogenesis and cellular response of dry eye will help develop new treatment strategies. The role of inflammation provides new directions for therapy, and developing drugs targeting the epithelial barrier, corneal nerves, goblet cells, immune cells, and cytokines may lead to better outcomes for dry eye patients.

journal homepage: https://pubmed.ncbi.nlm.nih.gov/25278793/