Dry Eyes, Are We Getting Anywhere?
Dry eye syndrome is one of the most common diagnoses encountered in ophthalmology. It is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. The prevalence of dry eye symptoms increases with age and it affects 80% of the population over the age of 80. Patients usually complain of gritty, sandy foreign body sensation and visual blurry vision that clears temporarily upon blinking which is attributed to tear film disruption over the cornea. Conventional non-invasive techniques for the diagnosis of dry eye include quantitative assessment of tear volume, tear film stability, tear dynamics and integrity of ocular surface epithelium.

Evolving current knowledge on different aspects of dry eye will certainly improve future diagnostic abilities leading to more effective therapeutic options. Various diagnostic tests are being used for recognising dry eye. More recently, video-meibography and meibometry have been used for screening meibomian gland dysfunction which has improved our understanding about pathophysiology of the dry eye. Although there is increasing quest for diagnosis of dry eye, it is equally important to make efforts to develop tools to quantify effects of dry eye on quality of life. Compromised visual function in dry eye can be quantified by measuring optical aberrations, serial videokeratographic/topographic analysis as well as by a functional visual acuity device which relies on rapid presentation of optotypes. An improved understanding of dry eye disease has increased our awareness that patients suffering from this disease experience significant impairments of daily living. Although not sight threatening, dry eye symptoms become progressively bothersome and exert an increasing burden on the patients. Studies have shown significant impact of dry eye on vision-related daily activities like reading, watching television and driving. Among these difficulty in reading is the most common complaint of these patients and also significantly lowers the quality of life. Most of the studies have evaluated impact of dry eye on reading using mainly interviewer-administered questionnaire. However, objective assessment combined with administration of questionnaire is probably the best way to evaluate reading disability in these patients.

The Salisbury Eye Evaluation is a population-based study designed to assess the impact of eye disease and physical impairment on disability. Landingham et al not only evaluated dry eye disability among these subjects using six-item questionnaire pertaining to dry eye symptoms, also did comprehensive assessment of their reading which included self-reported reading difficulty, reading habits and reading speed. In this study, dry eye was not associated with slower reading speed but associated with a greater likelihood of not reading newsprint and self-reported reading difficulty. It is crucial to know the impact of dry eye on quality of life and have objective way of assessing the same as this is highly prevalent condition in the population. Moreover, treatment of dry eye has been associated with improvements in ocular surface disease index scores and enhancement of patients' ratings regarding their ability to perform activities of daily living. So, objective tools of evaluation are important to evaluate vision-related quality of life and effect of treatment on improving it as dry eye results in a larger burden on the society through direct costs for care and treatment and indirect costs associated with decreased visual function and quality of life. Study by Landingham et al points in the direction of new metrics and opens further avenue of research on dry eye assessment. Future studies are required to further develop tools to objectively assess quality of life in dry eye patients.