Article

MAINTAINING CL TOLERANCE IN PATIENTS WHO HAVE MGD

Establishing a care routine for the eyelids and meibomian glands can help ensure comfortable lens wear.

It has been almost four decades since Korb and Henriquez first drew attention to the high prevalence of meibomian gland dysfunction (MGD) in their group of intolerant contact lens wearers,1 and the nature of the relationship between contact lenses and MGD has been a topic for debate ever since. The key question is, does MGD occur in contact lens wearers just as it does for anyone else, or do the lenses themselves have the potential to affect the structure and function of the meibomian glands?

The evidence accumulating over the last few years gives the definite impression that the needle is swinging in the direction of the second of these two possibilities. Several different groups around the world have produced data showing, for example, that contact lens wearers display significantly more meibomian gland dropout than comparable non-wearers do.2-5 They also have greater numbers of capped and plugged orifices.4 These outcomes are the same irrespective of whether GPs or soft lenses are worn, and there is no reason to expect that scleral lenses will be any different.

Faced with this knowledge, many eyecare practitioners will be confused as to what response is in the best interests of their contact lens wearers. Before becoming too anxious, however, a few important aspects to the data need to be borne in mind. First, any effects that do manifest will generally be quite small. The typical amount of gland loss due to lens wear is much less compared to the range of variation seen in a normal, asymptomatic population.6 So, while the changes can become significant in a large enough study, they may not be readily evident for any given individual in the usual clinical setting.

Second, the changes are self-limiting.4 This gives confidence that, even if some degree of modification is noted during the early stages of wear, the continued presence of the lens is unlikely to cause much further progression, even after many years.

These factors provide a safety net that allows an appropriate clinical response to usually be “watch and wait.” In most cases, successful contact lens wear can be expected to continue indefinitely, without significant complaint or any specific intervention.

Nevertheless, while following this path, it is crucial to really focus on the “watch” part so that early signs of intolerance can be spotted efficiently and promptly acted upon. The usual observations of meibomian gland structure and function are appropriate here, but it is also important to institute regular monitoring of the markers of potential intolerance. By and large, these will emerge from subjective inquiry, with a key red flag being any increase in the level of discomfort symptoms.

A scoring instrument that assigns a numerical value to the subjective discomfort response is very useful in these circumstances because it allows a “score history” to be established.7 Upward-trending scores, or significant variations from the historical pattern, can thus be more easily identified. Other indicators, such as frequency of artificial tear use and wearing time, can also be monitored across several visits to make sure that they are not deteriorating. In this respect, comfortable wearing time is probably a more useful measure compared to total wearing time.

STEPS TO MAINTAIN LENS TOLERANCE

What actions can be taken when the clinical picture, or our professional intuition, suggests that contact lens tolerance may be under threat?

Under normal circumstances, the ocular surface benefits from a functional reserve of meibomian gland activity. In other words, the capacity for meibum production exceeds what is needed at any one time. Alterations to the system, such as what might result from gland dropout or obstruction, tend to diminish this reserve and push the balance toward the point at which there is insufficient meibum. Clinical consequences may then ensue. Therefore, the aim of treatment is to improve meibomian gland function, at least back to the point of balance, and to ensure that an adequate flow of normal meibum reaches the surface of the tear film.

It is convenient to think of the treatment process for achieving this in three phases, as follows:

1) Clean Up The first line of attack involves improving lid hygiene by removing cellular and keratinized debris as well as removing obvious orifice blockages due to capping or plugging. In-office, this can be achieved with a lid debridement procedure in which a blunt-ended surgical spud is run gently back and forth along the lid margin (Figure 1).8

Figure 1. Debriding the lower lid margin with a blunt-ended surgical spud.

It is also worthwhile to check for and eliminate any Demodex infestation that may be present. These mites appear in greater numbers during contact lens wear,9 and their presence has been associated with both symptoms of discomfort10 and with meibomian gland dysfunction.11

2) Clean Out Next, material within the gland ducts that has become inspissated and is preventing normal function must be mobilized and moved out. As a first step, thermal softening using warm compresses, eye masks, or steam goggles is indicated, and this is generally followed by manual expression of the glands. Many practitioners use the technique of squeezing the lids between cotton tip applicators; however, it is often difficult to complete a successful maneuver in this way. In such circumstances, having a firm backing plate or expressor paddle against which to press can improve the procedure. Alternatively, several types of meibomian gland forceps are available, and these provide a more controlled interaction as well as permitting greater forces to be applied.

These procedures must be carried out in-office. Another such option is vectored thermal pulsation, which combines simultaneous therapeutic heating and gland expression into one procedure (Figure 2). In contact lens wearers, a single application of one such device improved subjective and objective indicators of intolerance for a period of several months afterwards,12 with anecdotal reports of significant efficacy out to 12 months.

Figure 2. Vectored thermal pulsation treatment in action.

3) Keep Clean While the first two phases will, hopefully, normalize the secretions from the meibomian glands, ongoing attention is needed to ensure that adequate function is maintained. Wearers should thus be encouraged to adopt lid hygiene procedures as a matter of routine. Regular use of lid wipes and scrubs is an appropriate recommendation. Depending on the clinical picture, it may also be advisable to suggest home use of one of the lid warming devices mentioned earlier, although this may not be necessary following vectored thermal pulsation.

A final point is that with the therapies currently available, we cannot hope to alter the appearance of the glands themselves. Dropout is a normal feature of aging,6 and once a gland has dropped out, it cannot be restored. Maintaining the function of the glands that remain is critical, therefore. Regular re-assessment is an important part of follow-up care, both to monitor progress and compliance as well as to screen for any evidence of a relapse.

Final Thoughts

Contact lens intolerance has always been a difficult condition to manage and explain, largely because so many unknowns surround the syndrome. Understanding the interaction between the lens and the meibomian glands has helped reduce that uncertainty and has led to a clear management strategy. Taken together, these factors should help reduce the numbers of those affected by contact lens intolerance and so increase the number of happy wearers. CLS

The author received an honorarium from Johnson & Johnson Vision Care, Inc. for writing this article.

REFERENCES

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