Nov 18, 2020 • 20 minutes read

How to diagnose and manage contact lens discomfort

Introduction

Written by
Jenny Sandh

Contact lens discomfort (CLD) may be the primary cause throughout the world why people aren’t satisfied with their contact lenses, or why they give up on wearing them at all. Especially the so-called end-of-day discomfort is one of the most common complaints by patients who stop wearing contact lenses. Contact lens discomfort can occur with any type of lens material, design, and wearing modality. Eye care professionals must be diligent in working with patients who experience discomfort. It’s crucial to start preventing and managing it early on – perhaps even before the onset of symptoms – so patients want to wear their contact lenses for a long time to come, and don’t drop out because of contact lens discomfort.

In this Handbook, I’ll give my summary of the TFOS International Workshop on Contact Lens Discomfort (named ‘TFOS report’ throughout this Handbook). It will elaborate on questions like what is contact lens discomfort, what are the signs and symptoms, and what should eye care professionals consider when helping a patient with symptoms of contact lens discomfort?

The Tear Film & Ocular Surface Society (TFOS) International Workshop on contact lens discomfort is an evidence-based report that was published in 2013, involved 79 international experts and spanned approximately over 18 months. A vast number of studies form the basis of the TFOS report. TFOS is a non-profit organisation, with the purpose to advance the research, literacy, and educational aspects of the scientific field of the tear film and ocular surface. This Handbook is not covering studies outside the scope of TFOS international workshop on Contact lens discomfort.


Chapters

Five practical questions & answers on contact lens discomfort

01
First things first: what is contact lens discomfort?

How do you classify contact lens-related discomfort?

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02
Signs & symptoms

How to evaluate your patients’ symptoms and signs to diagnose contact lens discomfort?

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03
What factors affect contact lens discomfort?

What to consider regarding contact lens material, design, and care to minimise contact lens discomfort?

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04
The impact on the ocular surface

What’s the relationship between contact lens discomfort and ocular surface?

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05
From diagnosing to managing contact lens discomfort

How to minimise contact lens drop-outs?

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01

First things first: what is contact lens discomfort?

How do you classify contact lens-related discomfort?

As an eye care professional practising in the area of contact lenses, you’ve probably seen many patients with contact lens discomfort. A variety of terms and vocabulary have been used to describe this problem. Typically, people with contact lens discomfort have symptoms like ocular discomfort of some sort, like dryness, irritation, and fatigue, and these symptoms probably increase during the day.

The TFOS report defines contact lens discomfort as follows:

Contact lens discomfort is a condition characterised by episodic or persistent adverse ocular sensations related to lens wear, either with or without visual disturbance, resulting from reduced compatibility between the contact lens and the ocular environment, which can lead to decreased wearing time and discontinuation of contact lens wear.

As the name of the condition implies, contact lens discomfort occurs while a patient wears contact lenses, and the problem mitigates when the patient removes the contact lenses. Always keep in mind though, that new contact lens wearers need to get used to wearing them – and physical signs may, or may not, be present in accompanying the adverse ocular sensations. So, before diagnosing the patient with contact lens discomfort or starting treatment, always allow the initial adaptation time. And, if removing the contact lenses doesn’t mitigate the discomfort, then evaluate other conditions that could cause the symptoms.

Be observant of the differences between contact lens-related dry eye and contact lens discomfort.

Lots of terms, lots of differences

It’s crucial for further diagnosis and management that you are observant of the differences between contact lens-related dry eye and contact lens discomfort. “Contact lens-related dry eye” refers to someone who has an already existing dry eye condition, which may or may not be exaggerated by wearing contact lenses. Throughout the literature, the terms contact lens dry eye, contact lens-related dry eye, and contact lens-induced dry eye are often used to describe symptomatic conditions during lens wear that mimics the symptoms of dry eye. However, when the lenses are removed, the symptoms no longer persist – so this scenario is not a dry eye condition. Therefore, you shouldn’t use these terms interchangeably with contact lens discomfort.

To distinguish the difference between contact lens discomfort and contact lens-related dry eye is vital when diagnosing and managing contact lens discomfort, as management of dry eye disease is a totally different story.

At the end of the day

In the clinical context, end-of-day discomfort is one of the most common reasons why people stop wearing contact lenses. Contact lens discomfort can occur with any lens material type or design and wearing modality. Hence, understanding your patient’s end-of-the-day comfort is a great tool to minimise drop-out from contact lenses.

How to classify contact lens discomfort

In figure 1, TFOS categorises contact lens discomfort into two major subclasses: the contact lens and the environment. These subclasses are divided further into their potentially contributing elements. The contact lens subclassification is categorised further into the material, design, wear, and lens care. The environment category is broken down further into patient factors (inherent and modifiable) and environment factors (ocular and external). Using this classification scheme in your daily practice will help you to visualise the possible reason(s) for the symptoms, and ultimately, in diagnosing and managing contact lens discomfort.

Figure 1: Classification scheme to visualise the possible reason(s) for the symptoms of contact lens discomfort, and support with diagnose and management (source: TFOS)

Future vision

Contact lens discomfort is a concern for patients and eye care professionals alike, as it can eventually lead to discontinuation of contact lens wear. We can describe successful contact lens wear best as a ‘harmonious coexistence of the contact lens on the eye, without any adverse effects’. Ultimately, the ideal contact lens has the material, design, and care characteristics, so it has an optimal fit, wear, vision, and comfort. Not only does this ensure the patient wouldn’t want to stop wearing them, but it also promotes ocular health and improves quality of life.

02

Signs & symptoms

How to evaluate your patients’ symptoms and signs to diagnose contact lens discomfort?

Although in practice, you probably see many patients with signs and symptoms of contact lens discomfort, in the literature, the clinical picture of the condition isn’t as well represented as dry eye disease. While the generic symptom ‘discomfort’ may be reason number one for people to stop wearing contact lenses, what the term ‘discomfort’ actually means to people is complicated. And, whether or not someone reports their symptoms of contact lens discomfort may be influenced by the patient’s motivation to wear contact lenses and by money.

It’s all about perception
The perception of symptoms of contact lens discomfort is complex. One of the most common symptoms is dryness, which appears to diminish when the lenses are removed and also seems to change during the wearing period – with increased symptoms in the afternoon and evening. Other than dryness, ‘scratchy’ and ‘watery’ sensations, blurry vision and irritation are reported. More seldom, people experience light sensitivity and eye soreness.

So, never underestimate the importance of asking follow-up questions when a patient explains their symptoms. Try to expand on the presented symptoms and take a broader medical history. Understanding your patient’s symptoms will help you in diagnosing the epidemiology of their symptoms.

Use symptoms rather than signs
Published literature on contact lens discomfort contains many references to traditional clinical tests that may be helpful in the diagnosis of the condition. Some suggestions are the assessment of pre-lens tear film, meibomian glands, bulbar and limbal hyperemia, and corneal and conjunctival staining. Many studies indicate there’s a wide range of clinical signs that come with contact lens discomfort. Some of the more common signs are poor lens wetting, rapid pre-lens non-invasive tear breakup times (NITBUT) and preocular fluorescein breakup times. It’s important to note that the evidence regarding signs and the correlation with the condition is weak.

Therefore, when diagnosing contact lens discomfort, it’s better to use symptoms as an outcome measure, rather than signs, because the symptoms directly relate to the patient’s experience with their contact lenses. You can use a questionnaire to assess the frequency and intensity of the symptoms – this will also indicate further management and treatment, whether there are clinical findings or not. One of the questionnaires that the TFOS report mentions is the Contact Lens Dry Eye Questionnaire.

When diagnosing contact lens discomfort, it’s better to use symptoms as an outcome measure, rather than signs. The symptoms directly relate to the patient’s experience with their contact lenses.

How do contact lens discomfort and dry eye disease interact and differ?
As symptoms of contact lens discomfort and dry eye disease are very similar, both conditions can intertwine. Patients who have traditional signs and symptoms of dry eye disease are more likely to have contact lens discomfort when they start wearing contact lenses. To the contrary, as the presence of dry eye disease increases with age, patients who haven’t been diagnosed yet with it at the time of being fitted with contact lenses, the suspected contact lens discomfort may instead be a manifestation of dry eye disease.

Also, a patient doesn’t need to have signs or symptoms of dry eye disease to suffer irritation when wearing contact lenses – and note relief when they remove them. On the other hand, practitioners often have patients with significant signs of dry eye disease, who’re able to wear contact lenses comfortably.

In short, patients with dry eye disease are more likely to have contact lens-related symptoms. As a practitioner, you have a difficult job in determining which factors have caused contact lens discomfort and concluding if the symptoms are either patient- or contact lens-related.

As one of the risk factors of dry eye disease is age, it’s wise to always pay extra attention to the quality of the tear film (with and without contact lenses on the eye), when fitting contact lenses on a presbyopic patient. Depending on the patient’s characteristics, you can determine the choice of lens material, wear time, as well as cleaning system and any suitable tear substitutes.

Future vision
To evaluate your patient’s signs and symptoms, you should combine the results from a questionnaire on symptoms with a thorough eye examination and anamnesis. The aim is to understand the reason behind your patient’s discomfort, to be able to support in wearing contact lenses comfortably – so to avoid drop-outs.

Must-watch

Video on how to assess the tear film stability via calculation of the tear film break up time (source: TFOS).

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03

What factors affect contact lens discomfort?

What to consider regarding contact lens material, design, and care to minimise contact lens discomfort?

What roles do lens materials and designs play when it comes to contact lens discomfort? These have been important questions in several studies. And while there have been significant developments in lens polymers, designs, replacement modalities, and care regimes over the last fifty years, the challenge of preventing and managing contact lens discomfort remains.

Material and design matter
Scientists and practitioners have questioned the influence of polymer chemistry, and various other material attributes that can be measured and quantified. The considered attributes are:

  • The bulk, such as water content, dehydration, Ionicity, oxygen transmissibility, modulus and mechanical factors.
  • The surface properties, such as friction, wettability, surface modification of contact lens materials.
  • Contact lens material chemistry.

Up to now, almost none of these attributes – with the possible exception of friction – appears to be associated directly with contact lens discomfort. Contact lenses of different brands and manufacturers will vary in terms of their design. As a practitioner, you probably recognise that the design of contact lenses affects their ability to fit the ocular surface properly and that this influences the overall performance. For example, for soft contact lenses, moderate on-eye movement (with tear exchange) and corneal coverage are essential, but its overall association with contact lens discomfort is not entirely clear. There is even less consensus about the influence of various design attributes on the condition. However, friction, size, shape, and contour of lens edges appear to be some of the most influential determinants of contact lens comfort for soft contact lenses.

Better care, better comfort
Contact lens care solutions, practices, and wear schedules are interesting when we look at understanding their role(s) in contact lens discomfort. Peer-reviewed literature doesn’t show specific formulations or components that may be associated with either increasing the discomfort or improving comfort. That said, we can probably all agree that regular contact lens care – including rub, rinse, and adequate soaking – is essential in wearing contact lenses comfortably. Also, replacing soft contact lenses regularly is best for ocular health, and could potentially improve comfort.

What about patient- and environment-related factors?
Apart from contact lens material, design, and care, the classification scheme in figure 1 also shows that there are several patient- and environment-related factors that can cause contact lens discomfort.

It shouldn’t be a surprise that the eye can detect and sometimes react to the presence of a contact lens – as the contact lens touches sensitive parts, like the cornea, lid margin and, to a lesser extent, the conjunctiva. Evidence from the literature shows some occasional patient-related factors associated with the condition, such as female sex, younger age, inadequate tear film quantity and quality, seasonal allergies, and the use of systemic medications. On the other hand, there is little evidence that ethnicity, blink rate and blinking patterns, systemic disease, diet, alcohol, smoking, cosmetic use, or psychological factors play a role in contact lens discomfort.

The TFOS report also indicates that literature supports that symptoms of contact lens discomfort can occur due to an increased tear evaporation rate from the lens surface, because of a reduction in the relative humidity. In addition to this, the movement of air (wind) and visual activities that make people blink less (such as the use of digital devices) may worsen signs and symptoms of the condition. For the role of other environmental factors on contact lens discomfort, such as temperature, altitude, smoky environments, air conditioning or indoor heating, there’s little concrete evidence.

If a patient can’t wear their contact lenses comfortably, it may help to make changes to the lens material, design, care system and replacement schedule.

Future vision
Surprisingly enough, there are not so many proven links between contact lens discomfort and factors like contact lens material, design and care system. The TFOS report concludes that much work should be done yet to unravel the complexities of the condition. That said, as eye care professionals, we can agree that if a patient can’t wear their contact lenses comfortably, it may help to make changes to the lens material, design, care system and replacement schedule.

04

The impact on the ocular surface

What’s the relationship between contact lens discomfort and ocular surface?

It’s obvious that the interactions of a contact lens with the ocular surface and tear film are critical in comfortably wearing contact lenses and the possible development of contact lens discomfort. But what is the impact of contact lenses on the ocular surface? And what are the links to the condition?

Figure 2: Anatomy of the human eye

Contact lenses and the cornea
The cornea serves as the major surface on which the lens sits and could play a significant role in contact lens discomfort, particularly as it relates to its neurobiology. Even though many publications examine corneal staining associated with contact lens wear, there’s only a weak link between contact lens discomfort and corneal staining – and it’s not a significant factor for more contact lens wearers.

Contact lenses and conjunctiva
The conjunctiva proved to be more closely linked to the development of contact lens discomfort. In some studies, bulbar conjunctival staining was found to be associated with it. The palpebral conjunctiva has a vital role in controlling the interaction with the ocular surface and lens. Two specific issues potentially linked to contact lens discomfort include alterations to the meibomian glands and to the leading edge of the palpebral conjunctiva, as it moves across the lens surface (the so-called “lid-wiper” zone). Contact lens wear does appear to impact the function of the meibomian glands, and reduced meibomian gland function has been associated with contact lens wear. Alterations to the lid-wiper area are more common in contact lens wearers with symptoms of contact lens discomfort, and some studies have related these tissue changes to the condition.

The TFOS report concludes that there is some evidence to suggest a link between conjunctival and lid changes with contact lens discomfort. The most substantial evidence is related to the meibomian gland and alterations to the lid-wiper area.

Contact lenses and tear film
The presence of a contact lens on the eye divides the tear film into a pre- and post-lens tear film, creating new interfaces with the ocular environment. Changes in the tear film occur after the lens is applied and during the contact lens wear. Additionally, biochemical differences are likely to exist between the pre- and post-lens tear film layers. Partitioning of the tear film after applying a contact lens and during wear causes some compositional changes that result in a less stable tear film on the front surface of the lens and less well-defined changes to the post-lens tear film layer. The resulting pre-lens tear film has reduced lipid layer thickness, reduced tear volume, and increased evaporation rate compared to the “normal” tear film.

Evidence specifically suggests that decreased tear film stability, increased tear evaporation, reduced tear film turnover, and tear ferning are associated with contact lens discomfort. And, tear film stability is recognised as a critical factor in the condition as well.

Future vision
When you investigate the source of contact lens discomfort, you should undertake a full examination of the anterior ocular structures that can be impacted by the contact lens. The TFOS report suggests particular attention to the importance of carefully assessing the meibomian glands and lid margins.

05

From diagnosing to managing contact lens discomfort

How to minimise contact lens drop-outs?

When your patient reports symptoms of contact lens discomfort, there are a few steps to take. First of all, a careful, individual assessment is necessary to eliminate concurrent conditions that may confuse the clinical picture. Next to that, you should determine the most likely cause(s) and identify corresponding treatment strategies.

Figure 3: Steps from reporting symptoms to management of contact lens discomfort

Anamnesis

A detailed history of the problem and the general status of the patient is a critical first step in the management of contact lens discomfort. The TFOS report suggests you should include the following key elements in your evaluation: age and sex of the wearer, timing and onset of symptoms, type of lens and lens material, care systems, lens replacement schedules, use of additional wetting agents, wear times, compliance and adherence to instructions, occupational environment, coexisting disease, and current medications.

It’s important to recognise that the symptom ‘discomfort’ is relatively non-specific and that it may come from many other sources than the contact lens.

Rule out underlying factors

Before starting management of contact lens discomfort, it’s essential to identify and treat coexisting diseases that may be responsible for the patient’s symptoms, such as ocular medicamentosa, systemic disease, eyelid disease, tear film abnormalities, and conjunctival and corneal diseases.

Take better care

The TFOS report writes that after all non-contact lens causes of the condition have been identified and treated, you should further focus on the contact lens care. Contact lens defects, such as edge chips and tears, deposits, and non-wetting surfaces, are typical causes of contact lens-related problems. Consider contact lens design properties, such as material properties, and on-eye fit and care solutions and their components or improper care regimens. Also, note that the solution in the blister pack of disposable lenses also can be a source of contact lens discomfort, particularly when the patient applies the contact lenses in the eye. Frequent and well-timed replacement of contact lenses may reduce or eliminate deposit formation.

Future vision

If a patient switches to a different care system, this may have some effect on deposit formation. Although changing lens material may be helpful, it isn’t easy to separate material from design and surface effects as a source of contact lens discomfort. Fitting with steeper base curves, using larger diameter lenses, alternating the back-lens surface shape, and using lenses with a thinner centre thickness may improve contact lens discomfort. But you should note that it’s challenging to manipulate lens parameters in isolation from each other, as altering one parameter may influence the other parameters.

Other suggested treatments include artificial tears and wetting agents and punctal occlusion, along with avoiding adverse environments (like aircraft cabins) and making sure to blink more often. It may be necessary to add treatments step by step to provide the patient the maximum possible relief from the condition.

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