Dry eye – an increasingly common challenge?

Since the relatively recent acceptance of the seingly increasing prevalence of dry eye, researchers with the interest and necessary skills have commenced in-depth studies of the condition.Research commenced in earnest probably only within the past 20–30 years and reached its peak in just the past 10–15 years. The results of those studies and the predictable creation of novel instrumentation, or the evolution of existing instrumentation, to address the clinical and laboratory needs of those researchers has resulted in the founding of a growing industry dedicated to equipping those interested in dry eye. Some of those same results also gave rise to novel or evolved in-eye preparations to address at least the symptoms of the disease.Many solutions, literally and figuratively, were released by companies who either already had similar products, sometimes intended as an adjunct treatment for contact lens wearers, or who had the manufacturing capabilities to enter the evolving dry eye-specific market. Some startups also entered the fray, and the situation today amounts to an established and expanding dry eye ‘industry’ populated by many old faces and several new ones.{{image2-a:r-w:400}}A significant milestone was the TFOS (Tear Film and Ocular Surface society) 2007 DEWS I (Dry Eye WorkShop I) report which, perhaps more than any other single ‘event’ ever, put dry eye on the ophthalmic professions’ map. While DEWS II (2017) addressed much of what has transpired since the foundations of the 2007 milestone and answered many of the perceived shortcomings of the landmark original, it ses that the professions involved perceive it almost as an anti-climax.The greatest contributions made by DEWS II centre on the acceptance of dry eye being a multifactorial disease, and that dry eye itself represents a continuum between two extres believed previously to be separate types – namely aqueous deficient dry eye and evaporative dry eye. The central pathophysiological concept now is a loss of homeostasis of the tear film.Importantly, the concept of ocular symptoms has been broadened to encompass ocular discomfort or visual disturbance. In the new definition, all aspects of dry eye are now related to the key aetiologies of tear film instability, hyperosmolality, and ocular surface inflammation and consequent damage. New data has also resulted in neurosensory abnormalities, including neurotrophic conditions (e.g., neurotrophic keratitis) being included in the definition for the first time.While the prevalence has not been confirmed to be increasing, there are good reasons to believe that it might be, e.g., the greying of the western world’s population, the pervasive invasion of digital devices into the working and leisure lives of people of all ages but most especially those younger than 40 years of age, the greater awareness of the condition among the general population and the relevant professions, and the activities of all the branches of the dry eye ‘industry’.The success of the latter can be measured by the release of graded palliative in-eye solutions for the spectrum of dry eye severity; the release of a few, and the research of many, therapeutic treatments for dry eye, including devices to treat contributors to the disease, e.g. MGD; and our ability to assess and quantify aspects of dry eye, especially tear film osmolality, albeit often expensively.The ability to assess factors that might indicate the presence of dry eye can mean earlier detection of either the condition or the likelihood that the condition will present itself sooner rather than later. Confounding all of those issues is the perplexing disconnect between signs and symptoms, i.e., some have few or no signs but significant symptoms, while others have obvious signs but few symptoms.To date, no single dry eye diagnostic factor has been identified – the nearest parameter to defining dry eye is tear film osmolality, but it is fallible. Rather, a cluster of signs and/or symptoms collectively might result in a ‘diagnosis’ of dry eye, which dovetails well with the acceptance of a multifactorial definition and a complex aetiology.Whereas in the past dry eye has been viewed as a probl affecting mostly older fales that might affect Asian races disproportionately, DEWS II has also confirmed that dry eye is present in those under 40, does affect Asians more commonly, but whose prevalence is hard to determine reliably (figures range from 5–50%, but can reach 75% in some populations). Few reliable epidiological studies, even from the past 10 years, have surfaced, hence the true prevalence rains unknown still.Given the current level of dry eye activity in acadic and clinical circles, the supporting instrument and device industries, and the pharmaceutical and quasipharmaceutical conglomerates already participating, it is unlikely that dry eye will prove to be a passing fad – rather it is more likely to become an expanding and increasingly influential pursuit by many entities.Image courtesy: Flickr | Kamil Porbinski