Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment

Abstract

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

FIGURE 1

Overlap of symptoms in dysfunctional tear syndrome (DTS) subtypes. There is a substantial overlap in the patient-reported symptoms of the types of DTS. Patients with subtypes of aqueous deficiency, blepharitis/meibomian gland dysfunction (MGD) – evaporative and nonevaporative – goblet cell deficiency/mucin deficiency, and exposure-related forms of DTS, including exposure keratopathy, may report symptoms of ocular discomfort, dryness, burning/stinging, grittiness or a foreign body sensation, photophobia, and blurred/fluctuating vision. Clinical evaluation with a battery of assessments and diagnostic techniques are needed for a differential diagnosis.

FIGURE 2

Flow chart of the DTS Panel clinical approach. A differential diagnosis is achieved through the DTS Panel clinical approach through examination of patients via a series of clinical assessments and diagnostic techniques. Patients with dysfunctional tear syndrome (DTS) are classified to one or more of the four DTS subtypes: aqueous deficiency, blepharitis/meibomian gland dysfunction, goblet cell deficiency/mucin deficiency, and exposure-related DTS. Treatment options are determined on the basis of the specific DTS subtype(s) identified, thus allowing for a directed treatment approach.

FIGURE 3

Meibomian gland orifices and expression of the meibomian glands. Image from a patient with posterior blepharitis/meibomian gland dysfunction (MGD). Obstruction of the orifices of the meibomian glands and alterations in the meibum, leading to turbid, thickened secretions, can occur in patients with blepharitis/MGD. © 1994 American Academy of Ophthalmology.

FIGURE 4

Corneal fluorescein staining. Image from a patient with aqueous deficiency. The disruption in the integrity of the corneal epithelium is highlighted by the application of fluorescein staining to the ocular surface. Moderate-to-severe staining with fluorescein is depicted in the photograph. Image courtesy of Karl Stonecipher, MD.

FIGURE 5

Staining of the conjunctiva with lissamine green. Image from a patient with aqueous deficiency. Vital dyes, such as lissamine green, may be used to visualize debris in the tear film and regions of the conjunctiva that are deficient in mucin. Moderate-to-severe lissamine green staining of the temporal aspect of the conjunctiva is shown. Image courtesy of Elizabeth Yeu, MD.

FIGURE 6

Staining of the conjunctiva with rose bengal. Image from a patient with aqueous deficiency. Rose bengal may be used to highlight areas of the conjunctiva that are abnormal or unhealthy in patients with dysfunctional tear syndrome (DTS). Moderate staining of the conjunctiva is shown with a classic pattern for keratoconjunctivitis sicca. © 1994 American Academy of Ophthalmology.

FIGURE 7

Schirmer strip test. Illustration of a patient undergoing Schirmer strip testing. Abnormalities in the production of the aqueous component of the tear film may be diagnosed using Schirmer strip testing. The Schirmer strip is placed in the inferior cul-de-sac near the lateral canthus.

FIGURE 8

Evaluation of the tear film meniscus with optical coherence tomography (OCT). Image of the cross-sectional area of the tear film meniscus with OCT. Evaluation of the tear film with a high-resolution OCT allows for the characteristics of the tear film to be quantified. The area of the inferior meniscus was calculated to be 0.05 mm² in this patient, which was within the normal range [77]. Image courtesy of Elizabeth Yeu, MD.

FIGURE 9

Visualization of the meibomian glands, tear film lipid layer, and partial blinking. Image of a patient with meibomian gland dysfunction (MGD) and exposure-related dysfunctional tear syndrome (DTS). Diagnostic systems designed for visualization of the meibomian gland (meibography) are also capable of providing an analysis of the thickness of the tear film lipid layer and an assessment of partial blinking. Note a decrease in lipid layer thickness of 46 nm in the right eye and 43 nm in the left eye; increased partial blinking OU; and meibomian gland truncation OD greater than OS. Image courtesy of Mark Milner, MD.