On slit lamp examination, the NDES wearers showed significantly longer pre-lens NIBUT (9.8 s vs. 6.6s, p ≤ 0.0001), had better lens surface wetting (3.4 vs. 2.4, 0 to 4 scale, p ≤ 0.0001), significantly lower levels of film deposit on lenses (0.45 vs. 0.92, 0 to 4 scale, p ≤ 0.0001), and significantly lower levels of most slit lamp signs (Table 5).
This study showed that participants with and without symptoms of CL-related dryness did not differ by age, gender, average hours of contact lens wear, or in the prevalence of silicone hydrogel lens use. Thus, to answer one of the study objectives, the CL-related dryness must be a result of the wearer's response to lens wear and cannot be easily predicted by demographic factors or wearing patterns alone.
The participants with CL-related dryness exhibited a wide range of signs that accompanied their habitual symptoms of dryness and discomfort that are commonly associated with DE. However, not one DE sign was present in a majority of these symptomatic participants. The most commonly noted sign was poor lens wetting (40%) followed by fast pre-lens NIBUT (39%) and preocular fluorescein BUT (39%). The diversity of clinical presentations by symptomatic participants suggests a range for causative factors of this condition. Even those participants who were given the same possible diagnosis showed a range of presentations. This diversity of clinical presentations emphasizes the need for practitioners to use a wide range of assessment techniques to screen potential CL patients and to evaluate both signs and symptoms in existing wearers, with an emphasis on symptoms. All these CL wearers had frequent and intense symptoms, but their ocular signs were less predictive of their struggle with comfortable lens wear. In addition, Table 4 shows the amount of overlap in the demographic features of the diagnostic groups, with no significant differences between groups for any of these factors.
An important finding of the study was that nearly one-quarter of these symptomatic SCL wearers showed no apparent signs of DE in a detailed DE examination. The high number of NDES participants, who presented with “occult” CL-related DE that caused symptoms but did not show itself in clinical signs, suggests that factors other than DE may contribute to CL-related dryness symptoms soft lens wearers. These possible factors include awareness of the lens edge or lens optic junctions, environmental stressors such as pollution or smoke, or choice of lens care product.
To evaluate the first of these factors, an assessment of lens fit was included in the DE work-up; however, this would not necessarily identify those participants suffering irritation from marginally small lens diameters. Because the true corneal diameter is over a millimeter larger than the horizontal visible iris diameter,18 it is not always obvious when a lens fails to give full corneal coverage. A further potential source of mechanical irritation with soft lenses arises from the front surface profile (e.g., optic zone junctions). This may explain the higher prevalence of symptoms in toric soft lens wearers noted in an earlier study.1 The lid margin, which comes into contact with the lens surface during blinking, is highly sensitive; Collins et al.19 found the upper lid margin to be only marginally less sensitive than that of the central cornea, whereas Lowther and Hill20 found that lower lid margin sensitivity sometimes exceeded that of the cornea. Another factor that might make lid margin sensitivity more critical in contact lens wear is the fact that it contains a range of mechanoreceptors, in contrast to the cornea which only contains free nerve endings whose prime function is to detect pain. It is also possible that some of the symptoms experienced by participants in this study were related to care products.
This DE examination was exhaustive, with many biomicroscopic observations of the ocular surface and tear film. Even though this battery of clinical tests went beyond what is typically done in clinical practice, tests alone would fail to identify a quarter of the symptomatic SCL wearers. It appears that for the foreseeable future, symptomatic SCL wearers will need a clear opportunity to express the degree of symptoms and guidance from their eye care practitioners on the choice of lens material, care regimen, or other aspects of lens wear that may help to alleviate them. We suggest the inclusion of simple, but systematic, symptom questions during the case history to identify symptomatic SCL wearers and then to use accompanying clinical signs to help in the differential diagnosis. Our team suggests use of the questions in Appendix 2 (available online at http://links.lww.com/OPX/A97) and scoring grid in Table 1 for this purpose.1
After symptomatic SCL wearers were identified by questionnaire, one objective of this study was to identify the most efficient objective assessment to classify affected patients. These patients may benefit from changes in lens type, lens care product, or management of environments that exacerbate dryness symptoms.3,11,20,21,22 The clinical observation of pre-lens tear stability through the PLTF-NIBUT or fluorescein TBUT tests was diagnostic in many wearers. These tests identified tear instability problems in approximately 40% of the symptomatic wearers and were the most commonly observed positive signs. This finding agrees with work done by Guillon et al. that found that, in general, lenses hold the tear film differently in symptomatic and asymptomatic SCL wearers, and that breaks in the central zones were most common.9 Tear stability tests, paired with tear volume results from the Schirmer 1 test with which nearly 20% of DE patients had low tear volume, identified a large group of patients who had underlying low tear volumes and/or poor tear stability, regardless of lens wear. Patients with this ATD type of presentation may need more aggressive management of their DE condition than a person with adequate, but unstable, tear film with SCL wear (SCLTI), where the choice of lens material or replacement schedule may help.
Observation of meibomian gland output was also an important part of the differential diagnostic tool kit in this study and identified a unique group. Not surprisingly, the participants with poor meibomian gland output were the oldest sub-group in this study. Therefore, examination for physical changes in the glands may be most efficient if used with older SCL wearers.
The biomicroscopic observation of tear meniscus height was less helpful in identifying patients with low tear volume, as <8% of participants showed poor volume by this test. A number of authors have been developing optical coherence tomography methods to measure tear meniscus height in laboratory-based research and have found significant correlation to symptoms.23–25 However, the clinical observation of tear meniscus height with a biomicroscope was relatively insensitive in the current study. Tear meniscus height may be an outcome for research trials, but unlikely to be useful in multicenter trials with a broad base of clinicians. In addition, significant corneal fluorescein staining was noted in fewer than one in five of these symptomatic SCL wearers and, like conjunctival lissamine green staining and lid wiper epitheliopathy signs, was one of the least useful tests in the series.
It is notable that there was a significant difference between groups in lid wiper epitheliopathy with the NDES group showing the lowest level. The prevalence of lid wiper epitheliopathy was lower than previously noted in symptomatic contact lens wearers. This may have been due to a less rigorous technique being used compared with previous studies. For instance, in the present study, only fluorescein was used to evaluate the lid wiper whereas Korb et al. supplemented this with Lissamine green.26
The fact that seven of the control participants were categorized as showing signs of DE may appear surprising; however, most of these cases were marginal and not severe enough to cause symptoms. For instance, four of the participants were categorized for signs, which were evident in one eye only, and only two of the participants showed inferior corneal staining > Grade 1.
There are a number of obvious limitations to the approach taken in this study. The DE test battery did not include all possible DE tests. For example, we did not evaluate tear osmolarity, which has been shown in some studies, to correlate with symptoms in SCL wearers in some, but not all, studies.4 Other tear components have shown weak relationship to symptoms; Glasson et al. showed that chemical analysis of tear proteins did not correlate to symptoms in SCL wearers.7 Instead, the study was restricted to tests that can be reasonably easily undertaken in normal CL practice. Furthermore, some of the DE assessments are subject to variability because of limitations of repeatability and reproducibility. An attempt was made to reduce inter-investigator variations through pre-study training and the use of detailed instructions; nevertheless, it is inevitable that, as with any multicenter clinical study, there will have been some measurement error. Finally, the fact that the potential DE etiology was determined as a secondary exercise by a review panel who was masked to participant demographics rather than by the investigators themselves removed bias that may have occurred based on seeing the patient in person.
Although it is mentioned as one cause of DE in the DEWS 2007 Report,27 dryness related to SCL wear is not a disease condition per se. In fact, in most cases, SCL removal eliminates the symptoms.5 Symptoms of SCL-related dryness often affects SCL wear patterns. Coping techniques include removing lenses earlier in the day and eventually ceasing lens wear altogether. Dryness symptoms have long been associated with discontinuation of SCL wear.10,28,29 This is not surprising because the symptomatic SCL wearers in this study reported an average of 3.5 to 4.3 h of uncomfortable SCL wear per day, depending on diagnostic group. Those hours represent a substantial proportion of their waking hours and represent a large degree of struggle with SCL wear.
In summary, this study has demonstrated the varied nature of CL-related dryness and the diverse range of underlying causes. Most notably, the study suggests that nearly one-quarter of dryness symptoms may relate to factors other than dryness on the surface of the eyes that would generate ocular signs. The effective management of CL-related dryness requires a comprehensive range of clinical assessments, subjective symptoms, and objective tests of tear supply, tear stability, tear quality, and the ocular surface's ability to retain them as an optical surface. Diverse management strategies will be required to incorporate the appropriate treatment to reduce symptoms in SCL wearers.
Robin L. Chalmers
2097 East Lake Rd
This study was designed by the authors and funded by Alcon Research, Ltd. Study sites included: Carolyn Begley, OD, MS; Tom Quinn, OD; Wilson Movic, OD; Gary Osias, OD; Anthony Verachtert, OD; Stephen Cohen, OD; William Bogus, OD; David Ross, OD; Joe Schwallie, OD, MS; Larry Wan, OD; Shane Kannarr, OD; Gill Woods, OD; and Kathy Dumbleton MSc, MCOptom. Clinical monitors were Rosemary Stewart and Susanna Jones of Visioncare Research, Ltd.
The appendices are available online at http://links.lww.com/OPX/A96 and http://links.lww.com/OPX/A97.
1. Young G, Chalmers RL, Napier L, Hunt C, Kern J. Characterizing contact lens-related dryness symptoms in a cross-section of UK soft lens wearers. Cont Lens Anterior Eye 2011;34:64–70.
2. Chalmers RL, Hunt C, Hickson-Curran S, Young G. Struggle with hydrogel CL wear increases with age in young adults. Cont Lens Anterior Eye 2009;32:113–9.
3. Riley C, Young G, Chalmers R. Prevalence of ocular surface symptoms, signs, and uncomfortable hours of wear in contact lens wearers: the effect of refitting with daily-wear silicone hydrogel lenses (senofilcon a). Eye Contact Lens 2006;32:281–6.
4. Nichols JJ, Sinnott LT. Tear film, contact lens, and patient-related factors associated with contact lens-related dry eye. Invest Ophthalmol Vis Sci 2006;47:1319–28.
5. Chalmers RL, Begley CG. Dryness symptoms among an unselected clinical population with and without contact lens wear. Cont Lens Anterior Eye 2006;29:25–30.
6. Guillon M, Maissa C. Dry eye symptomatology of soft contact lens wearers and nonwearers. Optom Vis Sci 2005;82:829–34.
7. Glasson MJ, Stapleton F, Keay L, Sweeney D, Willcox MD. Differences in clinical parameters and tear film of tolerant and intolerant contact lens wearers. Invest Ophthalmol Vis Sci 2003;44:5116–24.
8. Begley CG, Chalmers RL, Mitchell GL, Nichols KK, Caffery B, Simpson T, DuToit R, Portello J, Davis L. Characterization of ocular surface symptoms from optometric practices in North America. Cornea 2001;20:610–8.
9. Guillon M, Styles E, Guillon JP, Maissa C. Preocular tear film characteristics of nonwearers and soft contact lens wearers. Optom Vis Sci 1997;74:273–9.
10. Doughty MJ, Fonn D, Richter D, Simpson T, Caffery B, Gordon K. A patient questionnaire approach to estimating the prevalence of dry eye symptoms in patients presenting to optometric practices across Canada. Optom Vis Sci 1997;74:624–31.
11. Young G, Riley CM, Chalmers RL, Hunt C. Hydrogel lens comfort in challenging environments and the effect of refitting with silicone hydrogel lenses. Optom Vis Sci 2007;84:302–8.
12. Schafer J, Mitchell GL, Chalmers RL, Long B, Dillehay S, Barr J, Bergenske P, Donshik P, Secor G, Yoakum J. The stability of dryness symptoms after refitting with silicone hydrogel contact lenses over 3 years. Eye Contact Lens 2007;33:247–52.
13. Guillon M, Maissa C. Use of silicone hydrogel material for daily wear. Cont Lens Anterior Eye 2007;30:5–10.
14. McMonnies CW, Chapman-Davies A. Assessment of conjunctival hyperemia in contact lens wearers. Part I. Am J Optom Physiol Opt 1987;64:246–50.
15. Ong BL. Relation between contact lens wear and Meibomian gland dysfunction. Optom Vis Sci 1996;73:208–10.
16. Bron AJ, Evans VE, Smith JA. Grading of corneal and conjunctival staining in the context of other dry eye tests. Cornea 2003;22:640–50.
17. Korb DR, Herman JP, Greiner JV, Scaffidi RC, Finnemore VM, Exford JM, Blackie CA, Douglass T. Lid wiper epitheliopathy and dry eye symptoms. Eye Contact Lens 2005;31:2–8.
18. Hall LA, Young G, Wolffsohn JS, Riley C. The influence of corneoscleral topography on soft contact lens fit. Invest Ophthalmol Vis Sci 2011;52:6801–6.
19. Collins M, Seeto R, Campbell L, Ross M. Blinking and corneal sensitivity. Acta Ophthalmol (Copenh) 1989;67:525–31.
20. Lowther GE, Hill RM. Sensitivity threshold of the lower lid margin in the course of adaptation to contact lenses. Am J Optom Arch Am Acad Optom 1968;45:587–94.
21. Young G, Keir N, Hunt C, Woods CA. Clinical evaluation of long-term users of two contact lens care preservative systems. Eye Contact Lens 2009;35:50–8.
22. Fahmy M, Long B, Giles T, Wang CH. Comfort-enhanced daily disposable contact lens reduces symptoms among weekly/monthly wear patients. Eye Contact Lens 2010;36:215–9.
23. Wang J, Cox I, Reindel WT. Upper and lower tear menisci on contact lenses. Invest Ophthalmol Vis Sci 2009;50:1106–11.
24. Chen Q, Wang J, Shen M, Cai C, Li J, Cui L, Qu J, Lu F. Lower volumes of tear menisci in contact lens wearers with dry eye symptoms. Invest Ophthalmol Vis Sci 2009;50:3159–63.
25. Chen Q, Zhang X, Cui L, Huang Q, Chen W, Ma H, Lu F. Upper and lower tear menisci in Sjogren's syndrome dry eye. Invest Ophthalmol Vis Sci 2011;52:9373–8.
26. Korb DR, Greiner JV, Herman JP, Hebert E, Finnemore VM, Exford JM, Glonek T, Olson MC. Lid-wiper epitheliopathy and dry-eye symptoms in contact lens wearers. CLAO J 2002;28:211–6.
27. Definition and Classification Subcommittee of the International Dry Eye WorkShop. The definition and classification of dry eye disease: report of the Definition and Classification Subcommittee of the International Dry Eye WorkShop (2007). Ocul Surf 2007;5:75–92.
28. Young G, Veys J, Pritchard N, Coleman S. A multi-centre study of lapsed contact lens wearers. Ophthal Physiol Opt 2002;22:516–27.
29. Richdale K, Sinnott LT, Skadahl E, Nichols JJ. Frequency of and factors associated with contact lens dissatisfaction and discontinuation. Cornea 2007;26:168–74.
soft contact lens; dryness; symptoms; clinical signs
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