The pathophysiology, diagnosis, and treatment of dry eye disease

Abstract

Background: Dry eye disease (DED) is common; its prevalence around the world varies from 5% to 34%. Its putative pathogenetic mechanisms include hyperosmolarity of the tear film and inflammation of the ocular surface and lacrimal gland. Dry eye is clinically subdivided into two subtypes: one with decreased tear secretion (aqueous-deficient DED), and one with increased tear evaporation (hyperevaporative DED).

Methods: This review is based on pertinent publications retrieved by a selective PubMed search and on the authors' own clinical and scientific experience.

Results: The diagnostic evaluation of dry eye disease should include a detailed patient history, thorough split-lamp examination, and additional tests as indicated. Few randomized controlled therapeutic trials for dry eye have been published to date. Artificial tears of various kinds are recommended if the symptoms are mild. Lid hygiene is helpful in the treatment of hyperevaporative dry eye, while collagen or silicon plugs can be used for partial occlusion of the efferent lacrimal ducts to treat severe hyposecretory dry eye. The benefit of long-term topical anti-inflammatory treatment of moderate or severe dry eye disease with corticosteroids or cyclosporine A eye drops has been documented in clinical trials on a high evidence level. Orally administered tetraycycline derivatives and omega-3 or omega-6 fatty acids are also used.

Conclusion: The treatment of dry eye has evolved from tear substitution alone to a rationally based therapeutic algorithm. Current research focuses on pathophysiology, new diagnostic techniques, and novel therapies including secretagogues, topical androgens, and new anti- inflammatory drugs.

Figure 1

Meibomian gland dysfunction a) Meibomian gland orifices on the eyelid margin blocked by thickened meibomian secretion b) Appearance of healthy meibomian glands on meibography

Figure 2

Lid-parallel conjunctival folds (grade 1 according to Höh et al. [22])

Figure 3

Vital staining of the ocular surface in a patient with dry eye disease a) Fluorescein staining of the cornea b) Lissamine green staining of the conjunctiva

Figure 4

Semiquantitative assessment of surface staining. The van Bijsterveld Index divides the ocular surface into three regions: cornea, nasal conjunctiva, and temporal conjunctiva. Each zone is scored for severity on a scale of 0 to 3. The sum of the three zone scores gives the overall score. Values >3.5 are regarded as pathological (1)

Figure 5

Measuring tear film break-up time to assess tear film stability. a) Invasive method, using fluorescein and the slit lamp with a cobalt blue filter b) Noninvasive method, without fluorescein, using a keratograph. The exact time and area of break-up are determined

Figure 6

Schirmer test to measure tear secretion