Tears of an office worker

Systane Lubricating Eye Drops (Figure 1) are supplied by many eye care practitioners to help to relieve such symptoms. As of June 1 this year, they are also available from general practitioners on prescription. Although this may seem a double-edged sword to those who currently supply the drops privately from their practice and who fear a loss of revenue, the counter argument is that this will establish the Systane brand in the market to an extent which will likely lead to more patients asking about it in practice.

What is Systane?

Systane ingredients are listed in Table 1. Polyquad (polydronium chloride) serves as a preservative after the solution has been steam and filtration sterilised. Systane is available in multidose bottles of 5-15ml. There is also a preservative-free single dose vial formulation for those instances where Polyquad intolerance is suspected or predicted. The active ingredient is hydroxypropyl guar (HPG) which has an interesting origin. There are also two demulcents, polyethylene glycol and propylene glycol. A demulcent (derived from the Latin demulcere, ‘caress’) is an agent that forms a soothing film over a mucous membrane, relieving minor pain and inflammation of the membrane.

Hydroxypropyl guar gum is synthesised by the etherification reaction of non-ionic propylene oxide reagent with guar gum. Guar gum is a polysaccharide extracted from the seeds of the guar bean, grown in southern Asia for centuries. This modification can significantly improve the important properties of unmodified gum such as alkaline stability, hydrophobicity, solubility, biostability and so on. The degree of molar substitution in HPG gives it excellent water retention properties, and for this reason the compound is found in many modern applications, from building construction materials to shower gels.

Systane acts as a mucomimetic, the HPG serving to act in a way not dissimilar to the mucous layer of the tear film which, formed by the goblet cells of the surface tissues, allows better ‘wettability’ of the ocular surface. The HPG in the fluid drop binds to the hydrophobic surface of the cornea to form a gel. This gel is then able to maintain the position of the demulcents over the surface for longer so enhancing the lubricant activity.

Does it work?

As with any eye drop there have been many clinical trials published about the effectiveness of Systane since its launch five years ago. One study, a randomised controlled trial by Christensen et al,1 monitored 87 dry eye suffering volunteers and found HPG to have a measurable therapeutic benefit expressed both in terms of reduced symptoms and signs (such as desiccation staining on the cornea and conjunctiva). The therapeutic effects were demonstrated on rabbit corneas by first inducing surface changes by exposure to 0.01 per cent benzalkonium chloride. Exposure to three separate lubricants for one and a half hours followed. The Systane was the only drop to protect completely from desiccation and also to allow recovery of the compromised surface. Similar studies found similar findings.2

Clinical trials on humans have found the drop to be effective. Gifford et al3 assessed 32 patients in the general community by monitoring changes in subjective ocular irritation scores, conjunctival injection, tear meniscus height, and total conjunctival and corneal staining scores with use of Systane. The drop was used four times a day over a four-week period and there was a statistically significant improvement in all variables except for meniscus height. Its safety and prolonged activity have also made it a useful agent to relive discomfort following Lasik refractive surgery.4

Optician office trial

The publishing offices where this journal is produced are typical of the sort of modern working environment where patients may develop dry eye symptoms (Figure 2). There is constant air conditioning, no open windows available, and each office space has a multitude of computer terminals each being viewed for long periods by staff. We asked for volunteers to come forward who had had any history of dry eye type symptoms at all. We had 32 volunteers. Each was asked a series of questions and then given a supply of Systane eye drops to use for four times a day over a four-week period (Figure 3). Due to the non-clinical setting, the post-trial period was compared to the initial presentation in terms of a subjective rating score. Individuals were also asked for comments on the drop and its use.

Of the 32 participants, 30 (94 per cent) were female compared to around 70 per cent of the office population as a whole. Whether this reflects anything significant regarding a propensity towards dry eye symptoms or rather a willingness to take part in a subjectively rated trial on the part of women, it will be left to the reader to decide! The youngest volunteer was 24 and the oldest 56 with an average age of 36 years. Every participant reported having suffered some form of dryness of grittiness in the past 24 hours. They were then asked to describe when they most noticed their symptoms. Out of a choice of morning, afternoon, evening or all day, five participants (16 per cent) described their symptoms as being present all day, two (6 per cent) as in the morning, while the remaining 25 noticed their symptoms most markedly in the afternoon or evenings or both (78 per cent). This is typical of evaporative dry eye symptoms, increasing exposure throughout the day, enhancing tear disruption and therefore aggravating any symptom.

Participants were asked about their computer use and this ranged from three hours up to 10 hours per day. The average was 6.5 hours per working day. Most managed at least a 30-minute midday break and most were familiar with, if not fully adherent to, advice about regular breaks from the screen. 20 (62.5 per cent) had previously consulted a doctor or optometrist about their symptoms, the majority of these (18 of the 20) going for the latter rather than the doctor. Previously recommended products that had been tried were noted and a large range was cited, but the commonest type of preparation included a hyaluronate ingredient. Each participant was then asked to rate the severity of their symptoms based on a score of 1 for least severe up to 10 for very severe. The scores ranged from 1 to 9 with the average being 4.5.

The score was then reassessed at the end of the period. The first point of note is that no one rated their symptoms as worse (with a higher score). Assuming the drops have an impact then this is obviously to be expected. The greatest improvement was from 6 to 1, an improvement in score of 5. Six of the sample (19 per cent) noted no improvement in subjective score. All of these individuals had previously used other preparations and their starting scores were all over 4. The remaining 26 (81 per cent) all rated an improved score and the average improvement was of 2.5 points.

Feedback

Subjective score ratings are fraught with problems. Participants are keen to try out a new product and may bias their score. Without a randomised control, there is a significant element of how someone feels on the day at the time of asking and many variables may influence the score rating. However, as a simple indication of office worker tear profile, this simple study does suggest and confirm the following. First, evaporative dry eye symptoms are a problem in a modern office. Second, the majority of those assessed do benefit from symptomatic relief if they use Systane eye drops over a four-week period.

References

1. Christensen MT, Cohen S, Rinehart J. Clinical evaluation of an HP-Guar gellable lubricating eye drop for the relief of dryness of the eye. Current Eye Research, 2004; 28(1), 55-62.
2. Ubels J, Clousing D, van Haitsma T, Hong BS, Stauffer P, Asgharian B, Meadows D. Pre-clinical investigation of the efficacy of an artificial tear solution containing hydroxypropyl-guar as a gelling agent. Current Eye Research, 2004; 28(6), 437-444.
3. Gifford P, Evans BJW, Morris J. A clinical evaluation of Systane. Ophthalmology, 2006; 29(1), 31-40.
4. Durrie D, Stahl J. A randomised clinical evaluation of the safety of Systane Lubricant Eye Drops for the relief of dry eye symptoms following Lasik refractive surgery. Clinical Ophthalmology, 2008; 2(4), 973-978.

Acknowledgement

Thanks to Alcon for supply of the product.