Every optometrist who fits contact lenses knows what a problem many patients have with contact lens discomfort. It is likewise a significant clinical challenge.
Every optometrist who fits contact lenses knows what a problem many patients have with contact lens discomfort. It is likewise a significant clinical challenge. Most estimates suggest up to half of contact lens wearers experience this problem.1
But how do you define contact lens discomfort? To date, there has been little consensus regarding the condition in both the clinical and research community. The Tear Film and Ocular Surface Society initiated a workshop in 2012 similar to its Dry Eye Workshop (DEWS) and Meibomian Gland Dysfunction Workshop (MGD) in an attempt to standardize in the scientific and clinical communities the characterization of contact lens discomfort (CLD). The results of the entire workshop were published in Investigative Ophthalmology and Visual Science, along with an executive summary,1 which I’ll attempt to briefly summarize.
The first order of business for the group was to arrive at a consensus for the definition of contact lens discomfort: “Contact lens discomfort is a condition characterized 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.”
The workshop recognized that CLD develops after the initial adaptation a new contact lens wearer goes through, occurs while a contact lens is worn, and that removal of the contact lens “mitigates the condition (in particular the adverse ocular sensations).” The workshop participants felt that moving forward the terms "contact lens dry eye" or “contact lens-related dry eye” should be reserved for an individual who has a pre-existing dry eye condition which may be exaggerated with contact lens wear and should not be used when talking about CLD.
With more than 140 million contact lens wearers worldwide, CLD remains a major reason for our patients to discontinue contact lens wear. Studies report that between 12 percent and 51 percent of contact lens wearers drop out of contact lens wear with CLD the primary reason for discontinuation.1
The workshop stated: “While the precise ideology of CLD is yet to be determined, the use of symptoms as an outcome measure is appropriate, because it relates directly to the patients experience with contact lenses, and the motivation to seek and use treatment, regardless of the presence of observable signs.” The workshop participants believed that the contact lens dry eye questionnaire is the most likely candidate for widespread CLD assessment.
Other factors in CLD
The workshop participants considered contact lens materials, design, and care regarding CLD. The committee concluded, “There is no question that the design of contact lenses influences the ability to fit the ocular surface properly, and this is influential in terms of overall performance,” but “the size, shape, and contour of lens edges appears to be some of the most influential determinants of contact lens comfort for soft and rigid contact lenses.”
The workshop participants found that the peer-reviewed literature did not give a clear indication of specific contact lens solution formulations or components that may be associated with improving contact lens comfort. However, they did agree that, “Regular contact lens care by contact lens wearers, including rub, rinse, and adequate soaking (disinfection and cleaning) are important in the success of lens wear.”
The workshop participants also found that "increasing the frequency of replacement of soft contact lenses is ideal for ocular health and potentially improving comfort, although it is difficult to define the ideal replacement schedule."
What about corneal staining and CLD? The workshop participants concluded, “Despite many publications examining corneal staining associated with contact lens wear, overall there appears to be, at best, a weak link between CLD and corneal staining, and it is not a major factor for most contact lens wearers.”
The group also found no specific association with any hypoxic changes or markers of hypoxia that could be linked directly to CLD. The workshop found there was some evidence to “suggest a link between conjunctival and lid changes with CLD, with the strongest evidence being that related to meibomian gland and lid wiper epitheliopathy changes.”
The workshop participants were more direct regarding the contact lens interaction with the tear film, stating, “The evidence to date specifically suggests that decreased tear film stability, increased tear evaporation, reduced tear film turnover, and tear ferning are associated with CLD.” Tear film stability (via evaporation) was found to be a key factor in CLD. There appears to be no relationship between total protein, lactoferrin, and lysozyme levels with CLD.
The workshop participants also discussed the management and therapy of CLD. As with most disease processes, a careful history of the presenting problem and the general status of the patient is a critical first step in managing CLD. Coexisting pathologies (i.e., autoimmune disease, blepharitis, tear film abnormalities) may be responsible for the patient's symptoms and are important to be identified and treated before focusing on the contact lens as the source of discomfort.
After non-contact lens causes of CLD have been identified and managed, the focus shifts to the contact lens and care system. Contact lens design properties, material properties, and on-eye fit are all factors that must be considered. Care solutions and their components or improper care regimens also may at times contribute to CLD, and the benefits of daily disposable lenses may in part be due to the elimination of solution factors.
Frequent and appropriately timed replacement schedules may reduce or eliminate deposit formation and improve comfort. Fitting with steeper base curves, using larger diameter lenses, alternating the back lens surface shape, and using lenses with a thinner center thickness may improve CLD, according to the workshop participants.
The use of topical artificial tears and wetting agents, oral essential fatty acids, punctal occlusion, and topical medications along with avoiding adverse environments and altering blinking behavior have all been used in treatment of patients with dry eye and may be useful adjuncts in reducing CLD.
However, the workshop participants noted, “All these tactics may have limited effect on CLD, and incremental improvements in CLD may be all that can be expected reasonably from any single intervention. The addition of treatments in a stepwise manner may be required to provide the maximum possible relief.”
In conclusion, the workshop participants stressed, “It is important that the process of prevention and management of CLD start early, perhaps even before the onset of symptoms, to improve the long-term prognosis of successful, safe, and comfortable contact lens wear.”
The workshop is a good first step in defining CLD, identifying management and treatment options, and directing future research topics in the area.ODT
1. Nichols JJ, Willcox MDP, Bron AJ, et al. The TFOS International Workshop on Contact Lens Discomfort: Executive Summary. Invest Ophthalmol Vis Sci. 2013 Oct 18;54(11):TFOS7–TFOS13.