New advancements in diagnosing dry eye disease
What is a biomarker? A biomarker is a naturally occurring molecule, gene, or characteristic by which we can identify a particular pathological or physiological process (i.e. dry disease).
Biomarkers for Dry Eyes
Inflammatory biomarkers, such as MMP-9, Matrix metalloproteinase, is an endopeptidase and an inflammatory biomarker. The levels of MMP-9 correlate well with dry eye disease because inflammation of the ocular surface correlates with dry eye disease.
Meibomian gland imaging
When we know dry eye disease is present, we can further identify the subtype.
New advances in meibomian gland imaging are helping to determine the subtypes of dry eye disease. I use the slit-lamp to assess the degree of inspissation and telangiectasia of the lid margin. I make a subjective assessment of the percentage of meibomian gland openings and the meibum quality; whether it is oily, clear and fluid or more milky and opaque.
Looking at the integrity of the glands within the tarsus has recently been imaged with infrared-based non-contact techniques which can provide valuable objective information about the integrity of the meibomian glands. Researchers are investigating Spectral Domain Optical Coherence Tomography (OCT) for gland examination.
Tear film stability and volume
We can assess the tear film stability and volume by the fluorescein tear break-up time (TBUT) and by Schirmer’s testing. These are essential components of ocular surface examination by the ocular plastic surgeon.
They are subjective, and many factors influence them including the volume of fluorescein and the length of time observed.
Non-invasive techniques are becoming available to examine tear break-up time and also for examining the lipid layer thickness and the tear meniscus height.
Anterior segment OCT provides a non-invasive measure of the tear volume by quantifying the tear meniscus height. It correlates well with tear break-up time, corneal fluorescein staining and diagnosis of dry eye disease and is non-invasive.
Currently, anterior segment OCT is not part of routine ocular examination with DED, but may well become so, and it is also useful for assessing the degree of conjunctivochalasis which is a looseness of the conjunctiva which we commonly observe in patients with ocular surface disease and dry eye disease.
Advances in treatment for dry eye disease
We base treatment of dry eye on minimising the inflammation and optimising the various components of the tear film, with artificial tears being an essential part of patient comfort. Many lipid and oily based formulations look promising to help stimulate a healthy balanced ocular surface.
Anti-inflammatory therapies, polysaturated fatty acids, antibiotics of anti-inflammatory action, meibomian gland heating and expression are all therapies which contribute to the treatment of dry eyes and are mainline treatments.
Therapies for refractive cases of dye eye include autologous serum, amniotic membrane, bandage contact lenses and the additional treatment of punctual plugs.