Evaluation of ocular surface and tear function - A review of current approaches for dry eye

Abstract

An increasing prevalence of dry eye disease in the past decade has resulted in a greater focus on diagnostic methods for this condition. There has been a proliferation of technologies that attempt to quantify various aspects of tear function and ocular surface health. However, a cost-effective, simple, and efficient method remains elusive. In the Indian context, the majority of these patients present to the general ophthalmologist, and a clinical approach that is quick and easy to perform would allow widespread usage for accurate diagnosis. This article reviews currently available methods and their relevance to the general ophthalmologist.

Keywords: Dry eye disease; ocular surface; tear film.

Figure 1

The criteria used by the Dry Eye Workshop II (DEWS II) and Asia Dry Eye Society (ADES) to diagnose dry eye disease. (Reprinted with permission from references 18 and 19)

Figure 2

Fluorescein staining of the ocular surface – the three steps (Images from “Fluorescein Gallery Book” with permission)

Figure 3

The use of a yellow filter allows assessment of conjunctival staining with fluorescein

Figure 4

Tear Film Oriented Diagnosis (TFOD) – the fluorescein breakup patterns and their significance in diagnosing different types of dry eye. (FL - fluorescein). (Reprinted with permission from reference 26 with modification)

Figure 5

The inter-relationships between the vicious cycles of dry eye disease, meibomian gland dysfunction, and inflammation. All three coexist in eyes with chronic dry eye disease and tend to be self-propagating, resulting in loss of ocular surface homeostasis and damage

Figure 6

An example of an automated device (a) that provides measurements of non-invasive breakup time - NIBUT (b), tear meniscus height (c), lipid layer assessment (d), scales to grade ocular redness score (e), and meibography (f). These results are presented in a composite report that also includes an assessment of the extent of meibomian gland dropout (g). Clinical assessment of the same parameters is performed by using the Schirmer test, fluorescein tear breakup time (FBUT), and slit-lamp assessment of meibomian gland architecture, secretions, and inflammation (h)