Putting a Number to Soft Contact Lens Comfort with Questionnaire

Worldwide, there are about 150 million contact lens wearers, with the vast majority wearing soft contact lenses. This number sounds impressive, but is only about 2% of the approximately 50% of the world’s population that requires a vision correction.¹

So, what’s holding back the masses? Well, one issue is the continuing dilemma of contact lens dropout.

Several years ago, Dumbleton and colleagues surveyed over 4,000 wearers and noted that the most common reason for dropout in existing wearers was dryness and discomfort.²

Up until this time, dryness and general discomfort were the primary reason(s) recognized for dropout. A more recent study by Morgan and Sulley surveyed new wearers and reported some intriguing results that update our understanding of contact lens dropout.¹

In these new wearers, the dropout rate was in the 25% range (similar to dropout rates reported by other studies), and about 50% of the dropouts occurred within the first 60 days of lens wear.¹

The main reason for dropout in these wearers, however, was vision at 57%, followed by discomfort at 28%! For new wearers that did not dropout of contact lens wear, discomfort was still a primary complaints at 44%, but vision was only reported as a problem for at 7%.¹

Table 1: Overview of reasons for discontinuation in new wearers vs. a cross-section of general wearers.¹

*Employed in this paper

**Terms used in respective papers

***Values are the proportion of reasons in up to three selected by patients, so they do not sum to 100%

****Values represent the single main reason chosen by patients, so they sum to 100%

These results are interesting and suggest a few different ideas that help us better understand why patients drop out of contact lens wear. First, visual satisfaction is a key factor in contact lens satisfaction and subsequent dropout—perhaps even more than comfort in new wearers.

As well, it seems that existing wearers whose visual issues were adequately addressed may have experienced a decline in comfort over time, which is not a surprise, knowing how a soft contact lens can affect the ocular surface homeostasis by reducing the lipid layer and causing an increase in the blink rate and evaporation.³

A recent Review of Optometry article also noted that, amongst new and established patients, discomfort and vision issues were the major reasons for discontinued wear. Interestingly, this article noted that 74% of discontinued patients called out that they would be willing to return to lens wear if their issues could be resolved.⁴

Identifying contact lens discomfort is critical for the patient’s success as it has been noted that dry eye symptoms frequently occur earlier than physical signs.⁵

Considering the high dropout rates of existing patients, identifying those at risk is not being done very well. In most cases, the doctor determines who is suffering from discomfort and/or dryness by asking open-ended questions.

The fact that this methodology is flawed is called out by the fact that when Miller and colleagues were creating the Ocular Surface Disease Index, a survey that is considered the gold standard for quantifying dry eye symptoms, they noted that patients valued the level of dryness with their lenses as a leading reason to select a lens, but practitioners ranked it as the 9th most important reason for selecting a lens.⁵

Thus, there is a disconnect between the motivation of the patient and the perception of the doctor.

Taking into account the impact that dryness and discomfort can have on a patient’s success or failure with a soft contact lens, and the ineffective way the patient's experience is being assessed, tells us we need a more effective and efficient manner to determine the patient’s level of discomfort.

As doctors, we embrace test methodologies that are objective and provide us with easily accessible data that we can share with our patients to help diagnose a condition and then monitor our recommendations. Fortunately, we have such a tool in the Contact Lens Dry Eye Questionnaire-8, better known as the CLDEQ-8 validated questionnaire.

DeLoss and colleagues note in their article the need for targeted tools to identify those at risk for contact lens discomfort and specifically call out the use of short and easy-to-use validated questionnaires, such as the CLDEQ-8.⁴

Figure 1: Image of a sample CLDEQ-8.

The CLDEQ-8 was first introduced in 2012 from work by Begley and colleagues. This group took the comprehensive and significantly longer Contact Lens Dry Eye Questionnaire and determined if there was a subset of this questionnaire that was highly correlated to the overall opinion of patients regarding their soft contact lenses.⁵

This work occurred in a two-phase approach. Phase one was the item reduction, which was done with a group of 38 subjects, followed by phase two, the validation phase, which occurred amongst 379 subjects.⁵

In 2016, a cutoff score was determined from a data set of over 1,100 subjects during a 1-year observational study.⁶ Since this early work, the CLDEQ-8 has been translated and validated into at least eight languages in addition to the original English version, allowing this tool to be used extensively.⁷

The questionnaire is effective because it determines a standardized, efficient way to measure symptom-based conditions from the patient’s point of view.⁶ Importantly, and unlike already existing dry eye surveys, it queries the patient about symptoms specific to contact lens wear and asks about symptom patterns that are unique to a contact lens wearer’s experiences.

It achieves this by asking general dry eye/discomfort questions, but also assesses frequency and late-day intensity of coping strategies (ex., lens removal and closing eyes for relief) as well as visual quality (ex., blurry, changeable, and foggy vision) questions.

The result of this work established a cutoff criterion of ≥12 points. Patients who score at this value or greater have been correlated to have a more negative overall opinion of their lenses and could be at a much greater chance of dropping out of their lenses.

Chalmers was also able to determine the Clinically Important Difference (CID) from her work in the large-scale study of 1,100+ subjects at a level 3 points.⁶ The CID helps understand how much of a symptom score change is a meaningful difference in the real world. This CID is not the same as a just noticeable difference or even a statistical difference.

A CID is considered a step change large enough to correlate to a subjective global difference. As such, knowing the CID will allow the optometrist to know when a treatment plan that has been initiated is having a meaningful effect.⁵

Since the CLDEQ-8 is composed of eight questions, it enables a patient to very quickly complete the assessment. The scoring of the assessment is simply the sum of each question, with a final score ranging from 0 to 37. As noted, the cutoff score has been determined to be 12 or over and a CID of 3.

A best-in-class suggestion to implement this questionnaire is to have the patient fill it out during the pre-exam time so the doctor can use the score to help determine how successful the patient is with their current soft contact lens regime.

For those who score a 12 or above, the doctor has the objective data that should direct them to determine the root cause of the reduced performance; the contact lens, the care system, or a physiological reason for the higher score.

Once a treatment plan has been initiated, repeat the CLDEQ-8 after adaptation to the change(s) to determine the effectiveness of the plan, leveraging the CID as a guide for success. The CLDEQ-8 score is like your blood pressure—the lower the better. The score, therefore, is easy for most patients to understand.

Most patients embrace objective data that reinforces a change, so make sure to share the results of the CLDEQ-8 with the patient. Using this questionnaire as an education tool could be effective in obtaining better compliance, and in many cases, validity for the need and value of an upgrade. It could also help you identify patients at risk of dropout before that occurs.

Assess how this questionnaire would fit into your practice. Consider customizing it by adding in your practice name and possibly logo at the top, or even the addition of a green (8 and below) , yellow (9 to 11), and red (12 and above) color scheme to the score to make the final score even easier to understand.

In conclusion, consider leveraging this science-based, validated tool to put a number to soft contact lens comfort and give you and your practice the tool to keep your patients in the green when it comes to comfort.