In the blink of an eye

July 1, 2009

How to retain mositure on the ocular surface

Key Points

There is ample evidence in the literature1-11 indicating that VDT use is associated with a reduced blink rate, a more widely exposed ocular surface and a thinning of the lipid layer. These alterations reduce tear film stability, which instigates ocular blurring, burning, stinging and photophobia. People describe these symptoms as ranging anywhere from bothersome to visually debilitating depending on various circumstances such as their average daily length of VDT use, whether or not they wear contact lenses, and other environmental influences - such as air conditioning and pollution exposure.

Wetting agents can be helpful, but the more frequent eye drop instillation in required, the less likely people are to consistently follow-through. In many cases, contact lens wearers who experience ocular dryness assume the problem is with the lenses. In cases such as this, contact lens users often forgo wearing their lenses, when something as simple as the right lubricating eye drop could mean the difference between CL intolerance and comfort.

Study outcomes

The entire study cohort comprised 40 subjects who used VDTs for a daily average of six hours. Participants were randomized into two groups; group one included 20 male (12) and female (8) non contact lens wearers ranging in age from 28 to 53 and group two included 20 male (10) and female (10) contact lens wearers ranging in age from 25 to 36. The non-contact lens wearers used blink Intensive Tears (10 mL) unit dose twice daily in the morning and the afternoon; and the contact lens wearers used blink Contacts (10 mL) unit dose twice daily in the morning and afternoon.

The Ocular Surface Disease Index (OSDI) was among the tools used to measure signs and symptoms of ocular dryness at baseline and after three weeks. OSDI is a questionnaire that quantifies the specific impact of ocular dryness or feelings of dry eye on quality of life. The OSDI is assessed on a scale from 0 to 100, with higher scores representing greater ocular discomfort13,14 . At baseline, there was no significant difference in symptoms between the two groups according to results of the OSDI questionnaires. Participants from both groups described their symptoms at baseline as those that are associated with feelings of moderate dry eye - stinging, itching, blurring and foreign body sensation. At baseline, non-contact lens wearers' OSDI average was 35; after three weeks of twice daily blink Intensive the average OSDI dropped by 10 pointes to 25 in this group. Results were the same among contact lens wearers; the OSDI average was 35 at baseline and 25 after three weeks of twice daily blink Contacts.

We also performed the evaluation of the stability of tear film measuring the Non Invasive tear film Break Up Time with a keratometer (Tear Thinning Time)22 at baseline and after three weeks. In the non-contact lens group TTT was 20 at baseline and 25 after three weeks of twice daily of blink Intensive Tears; and in the contact lens group TTT was 17.5 at baseline and 25 after three weeks of twice daily blink Contacts.

We concluded that blink Intensive Tears and blink Contacts represent an effective support to the management of the feeling of dry eyes during the use of VDTs.

Other studies12,15,16 suggest that blink Lubricating Eye Drops' hyaluronic acid (HA) component is responsible for replenishing the tear film and helping retain moisture on the ocular surface for a longer period of time than some other lubricating eye drops. HA thins during blinking and thickens between blinks. This process facilitates quick, smooth spreading over the lens and ocular surface without blurring, and provides a resistance to drainage for longer ocular lubrication. The viscosity enhanced formula has been shown to hold moisture in the eye for more than 60 minutes.

Tolerant contact lens wearers have been shown17 to have an average 7 second longer T-BUT than intolerant lens wearers, and tolerant contact lens wearers have 50% less dryness symptoms than intolerant contact lens wearers. Clinical analysis12,18 indicates that blink Contacts Lubricant Eye Drops increases tear film breakup time by 3 seconds. This effect suggests that blink Contacts Lubricant Eye Drops can bring contact lens wearers from mid tolerance to high tolerance, and this capability has been demonstrated in clinical trials. My anecdotal experience suggests that a 3 second increase in T-BUT can mean the difference between successful contact lens patient care and failure to keep a patient in contact lenses. Contact lens tolerance is typically considered the ability to wear CLs nine or more hours per day.