Rationale for 24-hour management of dry eye disease: A review.

The symptom severity of patients with dry eye disease (DED) varies over a 24-hour period. It is typically worse upon waking than later in the morning and deteriorates towards the evening. Substantial differences in the characteristics and physical properties of the tear film, such as levels of inflammation, pH, osmolarity, volume and stability, also exist between night (sleeping) and day (waking), and over the course of the day itself. Data on diurnal variation in symptom severity and tear film characteristics have been reviewed to recommend a management strategy that supports the various needs of patients with DED over a full 24-hour period. Treatment strategies for DED must be matched to the variations in the severity of DED and to the environments that eyes are subjected to over a 24-hour period. While artificial tears are used to moisturise the ocular surface and reduce damage to the corneal epithelium during the day, gels are used at night-time; they are more viscous and have a longer ocular surface retention time than artificial tears. Several combinations of these products are currently available in tandem to support the 24-hour variation in tear film characteristics. The present review of published literature provides evidence that the approach of the daytime use of artificial tears to protect the eye from aggravating environmental factors in combination with the night-time use of gels to relieve more severe symptomatology. This, in turn, should provide optimal 'around-the-clock' DED management.