Contact Lens & Anterior Eye 38 (2015) 152–156
Contents lists available at ScienceDirect
Contact Lens & Anterior Eye journal homepage: www.elsevier.com/locate/clae
Ex vivo heat retention of different eyelid warming masks Zoé Lacroix, Stéphanie Léger, Etty Bitton ∗ École d’optométrie, Université de Montréal, Montreal, Quebec, Canada
a r t i c l e
i n f o
Article history: Received 7 September 2014 Received in revised form 18 December 2014 Accepted 21 January 2015 Keywords: Warm compresses Meibomian glands Meibomian gland dysfunction (MGD) Eyelid warming therapy
a b s t r a c t Purpose: Meibomian gland dysfunction (MGD) appears to be the most common cause of evaporative dry eye, in which the meibum has an altered chemical structure that increases its melting point. Eyelid warming masks slowly transfer heat, preferably between 40 and 45 ◦ C to the inner meibomian glands, in an attempt to melt or soften the stagnant meibum. This ex vivo study evaluates the heat retention properties of commercially available masks over a 12-min interval. Methods: Five eyelid-warming masks (MGDRx EyeBag® , EyeDoctor® , Bruder® , TranquileyesTM , Thera◦ Pearl® ) were heated following manufacturer’s instructions and heat retention was assessed at 1-min interval for 12 min on a non-conductive surface. A facecloth warmed with hot tap water was used as comparison. Results: All masks reached above 40 ◦ C within the first 2 min after heating and remained so for 5 min, with the exception of the facecloth, which lasted only 3 min and quickly degraded to 30 ◦ C within 10 min. The Bruder® and TranquileyesTM reached >50 ◦ C, after heating and the Bruder® maintained >50 ◦ C for nearly 6 min. The MGDRx EyeBag® , and Thera◦ Pearl® had the most stable heat retention between 2 and 9 min, remaining between the targeted temperature. Conclusions: Heat retention profiles are different for commercially available eyelid warming masks. This ex vivo study highlights that despite the popularity of the time-honored facecloth, it is poor at retaining the desired heat over a 5–10 min interval. Clinical studies need to corroborate these results, remembering that ocular tissue parameters may be factors to consider. © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
1. Introduction The most common cause of evaporative dry eye appears to be meibomian gland dysfunction (MGD) [1–3]. It is estimated that the prevalence of MGD is 38.9%, increasing with age [2,4,5]. Each eye possesses approximately 60 meibomian glands (25–40 on the upper eyelid and 20–30 on the lower eyelid), which, under normal circumstances, should secrete a clear, liquid oil, called meibum [6,7]. These glands are squeezed by the action of a normal blink to release the meibum, which is subsequently distributed by the action of the lids onto the ocular surface, to minimize the evaporation of the underlying tear film layers [2,8]. In patients with MGD, the meibum has an altered chemical structure that increases its melting point compared to the physiological 32 ◦ C [2,9,10]. The exact melting point of meibum in those suffering from MGD has yet to be determined, as the chemical composition of the secretions is variable and in turn affects its physical attributes [11]. Despite this variability, the melting point for
∗ Corresponding author. Tel.: +1 514 343 7302; fax: +1 514 343 2382. E-mail address: [email protected] (E. Bitton).
meibum in obstructed meibomian glands is reported to be between 32 and 45 ◦ C [11]. The resulting meibum in patients with MGD is stagnant and thickened. Even if the melting point of the meibum in MGD is below that of body temperature at 37 ◦ C, rendering the meibum liquid, hyperkeratinization [7] of the terminal duct and orifice of the gland prevents the meibum from being secreted. Consequently, the meibum accumulates in the gland ducts [7] and the force exerted by a simple blink is insufficient to release it onto the ocular surface, resulting in the underlying tear film being more vulnerable to evaporation. Patients with MGD, and hence evaporative dry eye, are typically more sensitive to evaporation effects from air currents resulting in decreased tear film stability [12,13]. Although management of MGD is not globally standardized, warm compresses are regarded as a primary therapy [2,6,14,15]. The therapeutic purpose of the warm compresses, placed on the closed eyelids, is to slowly transfer the heat from the compress, through the eyelid tissues to ultimately reach the inner meibomian glands, in an attempt to melt or soften the stagnant meibum. Ocular massage is typically advocated [14] following warm compress therapy to empty the ducts and pierce through the obstructive orifices of the meibomian gland, eventually increasing the lipid layer of the tear film [14]. Although the exact temperature for warm compress
http://dx.doi.org/10.1016/j.clae.2015.01.005 1367-0484/© 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
therapy in unknown, temperature of 40 ◦ C [10] to 45 ◦ C [16] have been advocated. Warm compresses have been shown to reduce dry eyes in patients with MGD by improving symptoms, tear film stability, tear evaporation, tear film lipid layer thickness and decreased meibomian gland orifice obstruction [10,17–20]. Despite its frequent recommendation by eye care practitioners (ECP), warm compress treatments are poorly standardized. In practice, typical recommendations include daily heating of the eyelids for 5–10 min using a warm wet facecloth, heated rice bags or even a hard boiled egg [2,6,14,15,21]. These methods have relatively unknown temperature behaviors, which establishes a rationale for the present study. ECPs note that patients are often noncompliant with the recommendations, which results in suboptimal and ineffective therapy leading to premature discontinuation of treatment [14]. This can make warm compress treatment frustrating for both ECPs and patients. Blackie et al. [16] reported reheating facecloths every 2 min to maintain a constant heat above 45 ◦ C for at least 4 min, to be effective for MGD. This would require a patient to be near a heating source (a sink or microwave oven) for the full 4 min, which may not always be convenient. To render some treatment options more patient-friendly and potentially improve compliance, several companies have developed commercially available warming eyelid masks that claim to maintain a constant temperature throughout the recommended 5–10 min [22–26]. Although commercially available eye masks have existed for a long time, these newer masks are taking into consideration the new knowledge of the temperature needed to soften the meibum, a fact that was not previously considered. Hence experimentation with different heat-retaining fillers for these eye masks has made them novel in the marketplace. It is of clinical interest to evaluate how well each of these eyelid masks retains the target temperature of 40–45 ◦ C over a 10-min interval. That being said, in order to remove the variability of eyelid thickness, tissue heat retention and distribution in human subjects, a control study was undertaken first. To that end, the objective of this ex vivo study was to evaluate and compare the heat retention properties of commercially available eyelid warming masks over a 12-min interval.
2. Materials and methods Five eyelid-warming masks and a warm facecloth (Table 1) were selected for this study to investigate their heat retention properties. The selected masks were the MGD Rx Eyebag® , The Eye Doctor® , Bruder eye hydrating compress, TranquileyesTM , Thera◦ Pearl® Eyeessential mask and a facecloth. To remove any influences from eyelid heat absorption, retention and distribution differences in human subjects, an ex vivo control study was performed using a non-conductive surface as a substrate. A 12 × 12 × 1 block of polystyrene rigid insulation board (Foamular® , CAN/ULC-S701, Type 3, CCMC 13431-L, Owens Corning, Canada) [27] was used due to its non-conductive properties and R-value of 5. An R-value is a measure of thermal resistance of a material or the capacity of a material to resist heat flow [28–30]. The R-value is used regularly in the construction industry to choose appropriate building materials that will reduce heating and cooling costs. Increasing R-values have greater insulating effectiveness and are typically more expensive [31]. For example, single pane glass, which is typically a poor insulator, has an R-value of 0.91. Softwoods, typically used for flooring, have R-values of up to 1.25. Blown fiberglass to insulate walls have an R-value between 3.7 and 4.3 depending on its thickness and polystyrene board (the substrate that was chosen for this study) has an R-value of 5.0 with a higher capacity to resist heat flowing through it. The experiment was conducted in a closed space protected from drafts. The
153
Fig. 1. Experiment arrangement (non-conductive 1 thick insulated polystyrene board, thermometer and evaluated mask).
room temperature and the insulator temperature were monitored to ensure environment stability. Each mask was left at ambient room temperature for several hours prior to the study. The temperature of each mask was then measured at 2 min (−2) and at 1 min (−1) prior to inserting in the microwave oven to establish baseline measures. Each eyelid mask was sequentially heated with a microwave oven following the manufacturer’s instructions. The same microwave oven was used for each procedure (Sharp Carousel 1100W). The eye mask was placed onto the Styrofoam board within 5–10 s of heating and its temperature was measured using a digital thermometer probe (Fisher Scientific Traceable Total-Range) placed underneath it, between the mask/cloth and the board, as shown in Fig. 1. The digital thermometer complies with ISO/IEC calibration and has a resolution of 0.1 ◦ C. Once the mask was placed on the board (time = 0), the temperature was measured at 1-min interval for 12 min. The procedure was repeated three times for each mask and the measurements were averaged and standard errors (SE) were calculated and plotted for comparison. The facecloth was heated using room temperature tap water heated for 20 s in the microwave oven to simulate hot tap water. The excess was wrung out, and the facecloth was folded to obtain three layers (to simulate an “at-home” procedure), and placed directly on the polystyrene board to be measured similarly to the other warming masks. Statistical analysis was performed using the nonparametric Mann–Whitney U-test at an alpha level of 0.05 using SPSS (version 17.0 for Windows). 3. Results Three trials per mask were recorded, averaged and plotted with standard error (SE) in Fig. 2. All masks reached a temperature above 40 ◦ C within the first minute, with the exception of the Thera◦ Pearl® which took 2 min. Three masks (MGDRx EyeBag® , The Eye Doctor® , Thera◦ Pearl® ) had the most stable heat retention over an 8-min interval, maintaining at the desired temperature of 40–45 ◦ C. The Bruder® and TranquileyesTM reached the highest temperatures of 54 ◦ C and 49 ◦ C, respectively within the first minute and maintained that temperature for the first 2 min before slowly decreasing. The Bruder® mask maintained a temperature above 50 ◦ C for the first 6 min and, although slowly decreasing afterwards, was not able to reach below 40 ◦ C at the 12-min mark. The TranquileyesTM maintained a temperature above 40 ◦ C for the first 4.5 min and subsequently held the targeted temperature for another 6 min. After the 10-min mark, TranquileyesTM fell below the desired range.
154
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
Table 1 Comparison of commercially available eyelid warming masks. Mask
Contents
MGDRx EyeBag® (The EyeBag Company)
Photo
Manufacturer instructions
Replacement
Flax seeds
Microwave for 30 s at full power (variable by microwave) Hold tips and gently shake to distribute heat
200 uses
32
The Eye Doctor® (The Body Doctor)
Mixed natural grains
Remove inner bag from cover Microwave inner bag for 30 s Hold tips and gently shake to distribute heat
150 uses
34
Bruder Eye Hydrating Compress (Bruder Healthcare)
MediBeads®
Microwave for 20 s Do not apply tightly
6 months if used daily
30
TranquileyesTM goggles (eyeeco)
Thermoeyes beads
Place beads gel pack in fabric pockets, place into net bag and microwave on high for 45 s in 1 cup of water Let stand for 1 min Remove from net and place gel packs and pocket into back of goggle
67
Thera◦ Pearl Eye-ssential mask (Bausch & Lomb)
Pearl Technology®
Microwave for 12 s
13
Warm facecloth
Aside from the facecloth, the TranquileyesTM mask lost heat quicker than any other mask. The facecloth, reached the targeted temperature quickly (within 1 min) and maintained it for only 3 min, subsequently degrading to 30 ◦ C within 10 min. The facecloth was significantly cooler than all other eyelid warming masks after the 4 min mark (p < 0.05 for all comparisons, respectively). The average ambient temperature and insulated surface temperature before measurement remained constant at 23.1 ◦ C and 22.5 ◦ C respectively. All masks were at room temperature prior to heating (time at −2 and −1 min mark in Fig. 2).
4. Discussion All eyelid warming masks increased in temperature following heating with the microwave oven. To be effective for MGD
Fold facecloth into 3 to create 3 layers Wet towel with hot (not burning) water
Manufacturer’s suggested retail price ($Cdn approx)
5
treatment the eyelid masks should reach target temperatures of 40–45 ◦ C [10,16] for several minutes, independent of the composition of its heat retaining elements. The facecloth is poor at retaining heat at the desired temperature for the required 5–10 min, which is typically recommended by ECPs for MGD therapy. This is not to take anything away from the time-honored warm facecloth therapy, which has shown to improve symptoms, the lipid layer and tear film stability [10,16,18,32]. Even Olson et al. [10] demonstrated that the lipid layer thickness was enhanced using a warm facecloth that was kept >38 ◦ C by reheating it every 2 min. With a better understanding of the therapeutic temperature needed to liquefy the meibum, a warm facecloth can still be advocated, but would have to be re-heated every 2 min, for a total of at least 4 min, to maintain a high enough temperature to affect the meibum in the inner meibomian glands [16]. Some eyelid warming masks require a microwave oven for heating with specific instructions on wattage and heating times,
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
155
Fig. 2. Average temperature (◦ C) of three trials ± SE reached for each eyelid warming mask over 12 min. Time 0 is immediately following the heating of the mask.
however patients are unlikely to change their appliance to comply with manufacturer’s instructions for an eyelid mask. This may result in potentially over or under heating the mask and affect its efficacy. In this study, the same microwave oven (1100 W) was used to heat each mask to standardize procedures, however that specific wattage may not have been appropriate for some masks. For example the MGDRx Eyebag® requires 30 s at full power, however this is variable depending on the wattage of the microwave oven. The Bruder® eye mask demonstrated the highest heat retention throughout the 12 min, with initial temperatures >50 ◦ C for the first 6 min after heating. These elevated temperatures have the potential to cause a first-degree contact burn to the skin surface of the eye. Fortuitously, the act of removing a mask from a microwave oven would alert the user if the mask was too hot to the touch and should avoid any potential for contact burns. Although the manufacturer’s recommendations of 20 s was followed for the Bruder® eye mask, it is plausible that the 1100 W microwave oven used in this study was too powerful, rendering it warmer than expected. Nonetheless, ECP need to remind patients to “test” any eyelid warming mask prior to placing it on the eyelid to prevent contact burns [33]. The contents of the warming eyelid masks used in this study (Table 1) vary from natural grains to specially developed heat beads, each with potentially differing heat retention properties. Some masks recommend replacement after a certain amount of uses. For example the Eye Doctor® advises a change after 150 uses. A therapy of twice a day would require a replacement every 2.5 months whereas a daily use would require a change in 5 months. Similarly, the MGDRx Eyebag® recommends a change every 200 uses, requiring a change every 3.3 months for twice a day therapy and 6 months for daily use. The recommendation to change the Bruder® is twice a year. The Thera◦ Pearl® has a washable plastic cover, which may render it more appealing to patients who want to clean their mask regularly from sweat, makeup and cream transferred from their face. Advantages of the facecloth are its availability, minimal costs and ease of washing. More importantly, there are still some people who do not possess a microwave oven, making the warm facecloth one of the only therapies available to them. The cost, reusability and availability of each mask will likely influence the ECP’s or the patient’s decision of which one is best suited for them. Emerging research and a better understanding of MGD should assist the ECPs in recommending therapeutically effective and evidence-based eyelid warming therapies to their patients. In addition to eyelid masks, promising new eyelid warming technologies include steam [17,19,34,35], thermal [36–39] and chemically activated disposable sachets [40]. Aside from the effect on the meibum,
warm compresses can also transiently degrade vision from the light pressure of the compress [41]. This study was an ex vivo study to assess the heat retention of different eyelid warming masks without the influence of the eyelid tissue. Ongoing clinical studies will compare the heat retention of different eyelid warming masks on participants, keeping in mind that different conduction properties of eyelid skin may be a factor to consider. To prevent over or under heating, manufacturers should consider including heating times according to microwave oven wattage. 5. Conclusion Heat retention profiles are different for commercially available eyelid warming masks. This study brings further awareness that the time-honored warm facecloth, which continues to be strongly recommended by ECP, is poor at retaining heat over a 5–10 min interval without reheating it at frequent intervals. ECPs should educate patients/staff about the differences of commercially available eyelid warming masks, and alter their instructions with respect to the facecloth to maintain a therapeutically effective temperature. Ineffective therapy due to poor heat retention may lead to discouragement and discontinuation of treatment. Conflict of interest None of the authors have any financial interests with any of the products mentioned. Acknowledgments The authors would like to thank W. Wittich for statistical analysis and M. Gloin for assistance with graphics. References [1] The definition and classification of dry eye disease: report of the definition and classification subcommittee of the international dry eye workshop. Ocul Surf 2007;5(2):75–92. [2] Bron AJ, Tiffany JM. The contribution of meibomian disease to dry eye. Ocul Surf 2004;2(2):149–64. [3] Foulks GN, Bron AJ. Meibomian gland dysfunction: a clinical scheme for description, diagnosis, classification, and grading. Ocul Surf 2003;1(3): 107–26. [4] Hom M, Martinson J, Knapp L, Paugh J. Prevalence of meibomian gland dysfunction. Optom Vis Sci 1990;67(9):710–2.
156
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
[5] Hykin P, Bron A. Age-related morphological changes in lid margin and meibomian gland anatomy. Cornea 1992;11:334–42. [6] Kanski J, Bowling B. Eyelids. In: Clinical ophthalmology: a systemic approach. 7th ed. Edinburgh: Elesvier Saunders; 2011. p. 2–37. [7] Knop E, Knop N, Millar T, Obata H, Sullivan DA. The international workshop on meibomian gland dysfunction: report of the subcommittee on anatomy, physiology, and pathophysiology of the meibomian gland. Invest Ophthalmol Vis Sci 2011;52(4):1938–78. [8] Linton R, Curnow D, Riley W. The meibomian glands: an investigation into the secretion and some aspects of the physiology. Br J Ophthalmol 1961;45(7):18–23. [9] Terada O, Chiba K, Senoo T, Obara Y. Ocular surface temperature of meibomia gland dysfunction patients and the melting point of meibomian gland secretions. Nihon Ganka Gakkai Zasshi 2004;108:690–3. [10] Olson M, Korb D, Greiner J. Increase in tear film lipid layer thickness following treatment with warm compresses in patients with meibomian gland dysfunction. Eye Contact Lens 2003;29(2):96–9. [11] Bron A, Tiffany J, Gouveia S, Yokoi N, Voon L. Functional aspects of the tear film lipid layer. Exp Eye Res 2004;78:347–60. [12] King-Smith P, Nichols J, Nichols K, Fink B, Braun R. Contributions of evaporation and other mechanisms to tear film thinning and breakup: a review. Optom Vis Sci 2008;85:623–30. [13] Kimball S, King-Smith E, Nichols J. Evidence for the major contribution of evaporation to tear film thinning between blinks. Invest Ophthalmol Vis Sci 2010;51(12):6294–7. [14] Geerling G, Tauber J, Baudouin C, Goto E, Matsumoto Y, O’Brien T, et al. The international workshop on meibomian gland dysfunction: report of the subcommittee on management and treatment of meibomian gland dysfunction. Invest Ophthalmol Vis Sci 2011;52(4):2050–64. [15] Blepharitis/meibomitis.Gertenbilth A, Rabinowitz M, editors. The Wills eye manual: office and emergency room diagnosis and treatment of eye disease. 6th ed. Philadelphia Wolters Kluwer: Lippincott Williams & Wilkins; 2012. p. 125. [16] Blackie C, Solomon J, Greiner K, Holmes M, Korb D. Inner eyelid surface temperature as a function of warm compress methodology. Optom Vis Sci 2008;85(8):675–83. [17] Pult H, Riede-Pult BH, Purslow C. A comparison of an eyelid-warming device to traditional compress therapy. Optom Vis Sci 2012;89(7): 1035–41. [18] Goto E. Improvement of tear stability following warm compression in patients with meibomian gland dysfunction. Cornea 2000;19(6):90. [19] Matsumoto Y, Dogru M, Goto E, Ishida R, Kojima T, Onguchi T, et al. Efficacy of a new warm moist air device on tear functions of patients with simple meibomian dysfunction. Cornea 2006;25:644–50. [20] Mori A, Shimazaki J, Shimmura S, Fujishima H, Oguchi Y, Tsubota K. Disposable eyelid-warming device for the treatment of meibomian gland dysfunction. Jpn J Opthalmol 2003;47:578–86. [21] Freedman H, Preston K. Heat retention in varieties of warm compresses: a comparison between warm soaks, hard-boiled eggs and the re-heater. Ophthalmol Surg 1989;20:846–8.
[22] Narayan R. Meibomian gland dysfunction. Optician 2012;3(8):16–21. [23] TheEyeBagCompany. MGDRx EyeBag; 2013. Available from: http://www. eyebagcompany.com/ [accessed 15.11.13]. [24] Bruder. Moist Heat Compresses; 2013. Available from: http://www.bruder. com/eye/products/ [accessed 15.11.13]. [25] TheBodyDoctor. The Eye Doctor; 2013. Available from: http://www.the-bodydoctor.com/the-eye-doctor [accessed 15.11.13]. [26] eyeeco. tranquileyes; 2013. Available from: http://www.eyeeco.com/ [accessed 15.11.13]. [27] Extruded Polystyrene Rigid Insulation [Internet]. OWENS CORNING CANADA LP; 2011. Available from: http://insulation.owenscorning.ca/assets/0/188/ 9005b9ef-1bb5-469c-b0c2-9540c3aa4108.pdf [28] Insulation: U.S. Department of Energy; 2012. Available from: http://energy.gov/ energysaver/articles/insulation [accessed 15.12.14]. [29] R-values of Insulation and Other Building Materials: Arch Media Group LLC; 2014. Available from: http://www.archtoolbox.com/materials-systems/ thermal-moisture-protection/rvalues.html [accessed 15.12.14]. [30] R-Value: North American Insulation Manufacturers Association; 2014. Available from: http://www.naima.org/glossary/entry.php?entryID=23 [accessed 15.12.14]. [31] R-Value Table: Insulation Values For Selected Materials: Colorado Energy; 2014. Available from: http://www.coloradoenergy.org/procorner/stuff/ r-values.htm [accessed 15.12.14]. [32] Paugh J, Knapp L, Martinson J, Hom M. Meibomian therapy in problematic contact lens wear. Optom Vis Sci 1990;67:803–6. [33] Alden N, Rabbitts A, Yurt R. Contact burns: is further prevention necessary? J Burn Care Res 2006;27(4):472–5. [34] Mitra M, Menon G, Casini A. Tear film lipid layer thinkcness and ocular comfort after meibomian therapy via latent heat with a nivel device in normal subjects. Eye 2005;19:657–60. [35] Spiteri A, Mitra M, Menon G. Tear lipid layer thickness and ocular comfort with a novel device in dry eye patients with and without Sjogren’s syndrome. J Fr Ophthalmol 2007;30:357–64. [36] Greiner J. Long-term (12-month) improvement in meibomian gland function and reduced dry eye symptoms with a single thermal pulsation treatment. Clin Exp Ophthalmol 2013;41(6):524–30. [37] Korb D, Blackie C. Case report: a successful LipiFlow treatment of a single case of meibomian gland dysfunction and dropout. Eye Contact Lens 2013;39(3):e1–3. [38] Greiner J. A single LipiFlow® thermal pulsation system treatment improves meibomian gland function and reduces dry eye symptoms for 9 months. Curr Eye Res 2012;37:272–8. [39] Lane S, DuBiner H, Epstein R, Ernest P, Greiner J, Hardten D, et al. A new system, the LipiFlow, for the treatment of meibomian gland dysfunction. Cornea 2012;31(4):396–404. [40] Sim H, Petznick A, Barbier S. A randomized, controlled treatement trial of eyelid warming therapies in meibomian gland dysfuntion. Ophthalmol Ther 2014;3:37–48. [41] Solomon J, Case C, Grenier J, Blackie C, Herman J, Korb D. Warm compress induced visual degradation and Fischer–Schweitzer polygonal reflex. Optom Vis Sci 2007;84:580–7.
Contents lists available at ScienceDirect
Contact Lens & Anterior Eye journal homepage: www.elsevier.com/locate/clae
Ex vivo heat retention of different eyelid warming masks Zoé Lacroix, Stéphanie Léger, Etty Bitton ∗ École d’optométrie, Université de Montréal, Montreal, Quebec, Canada
a r t i c l e
i n f o
Article history: Received 7 September 2014 Received in revised form 18 December 2014 Accepted 21 January 2015 Keywords: Warm compresses Meibomian glands Meibomian gland dysfunction (MGD) Eyelid warming therapy
a b s t r a c t Purpose: Meibomian gland dysfunction (MGD) appears to be the most common cause of evaporative dry eye, in which the meibum has an altered chemical structure that increases its melting point. Eyelid warming masks slowly transfer heat, preferably between 40 and 45 ◦ C to the inner meibomian glands, in an attempt to melt or soften the stagnant meibum. This ex vivo study evaluates the heat retention properties of commercially available masks over a 12-min interval. Methods: Five eyelid-warming masks (MGDRx EyeBag® , EyeDoctor® , Bruder® , TranquileyesTM , Thera◦ Pearl® ) were heated following manufacturer’s instructions and heat retention was assessed at 1-min interval for 12 min on a non-conductive surface. A facecloth warmed with hot tap water was used as comparison. Results: All masks reached above 40 ◦ C within the first 2 min after heating and remained so for 5 min, with the exception of the facecloth, which lasted only 3 min and quickly degraded to 30 ◦ C within 10 min. The Bruder® and TranquileyesTM reached >50 ◦ C, after heating and the Bruder® maintained >50 ◦ C for nearly 6 min. The MGDRx EyeBag® , and Thera◦ Pearl® had the most stable heat retention between 2 and 9 min, remaining between the targeted temperature. Conclusions: Heat retention profiles are different for commercially available eyelid warming masks. This ex vivo study highlights that despite the popularity of the time-honored facecloth, it is poor at retaining the desired heat over a 5–10 min interval. Clinical studies need to corroborate these results, remembering that ocular tissue parameters may be factors to consider. © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
1. Introduction The most common cause of evaporative dry eye appears to be meibomian gland dysfunction (MGD) [1–3]. It is estimated that the prevalence of MGD is 38.9%, increasing with age [2,4,5]. Each eye possesses approximately 60 meibomian glands (25–40 on the upper eyelid and 20–30 on the lower eyelid), which, under normal circumstances, should secrete a clear, liquid oil, called meibum [6,7]. These glands are squeezed by the action of a normal blink to release the meibum, which is subsequently distributed by the action of the lids onto the ocular surface, to minimize the evaporation of the underlying tear film layers [2,8]. In patients with MGD, the meibum has an altered chemical structure that increases its melting point compared to the physiological 32 ◦ C [2,9,10]. The exact melting point of meibum in those suffering from MGD has yet to be determined, as the chemical composition of the secretions is variable and in turn affects its physical attributes [11]. Despite this variability, the melting point for
∗ Corresponding author. Tel.: +1 514 343 7302; fax: +1 514 343 2382. E-mail address: [email protected] (E. Bitton).
meibum in obstructed meibomian glands is reported to be between 32 and 45 ◦ C [11]. The resulting meibum in patients with MGD is stagnant and thickened. Even if the melting point of the meibum in MGD is below that of body temperature at 37 ◦ C, rendering the meibum liquid, hyperkeratinization [7] of the terminal duct and orifice of the gland prevents the meibum from being secreted. Consequently, the meibum accumulates in the gland ducts [7] and the force exerted by a simple blink is insufficient to release it onto the ocular surface, resulting in the underlying tear film being more vulnerable to evaporation. Patients with MGD, and hence evaporative dry eye, are typically more sensitive to evaporation effects from air currents resulting in decreased tear film stability [12,13]. Although management of MGD is not globally standardized, warm compresses are regarded as a primary therapy [2,6,14,15]. The therapeutic purpose of the warm compresses, placed on the closed eyelids, is to slowly transfer the heat from the compress, through the eyelid tissues to ultimately reach the inner meibomian glands, in an attempt to melt or soften the stagnant meibum. Ocular massage is typically advocated [14] following warm compress therapy to empty the ducts and pierce through the obstructive orifices of the meibomian gland, eventually increasing the lipid layer of the tear film [14]. Although the exact temperature for warm compress
http://dx.doi.org/10.1016/j.clae.2015.01.005 1367-0484/© 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
therapy in unknown, temperature of 40 ◦ C [10] to 45 ◦ C [16] have been advocated. Warm compresses have been shown to reduce dry eyes in patients with MGD by improving symptoms, tear film stability, tear evaporation, tear film lipid layer thickness and decreased meibomian gland orifice obstruction [10,17–20]. Despite its frequent recommendation by eye care practitioners (ECP), warm compress treatments are poorly standardized. In practice, typical recommendations include daily heating of the eyelids for 5–10 min using a warm wet facecloth, heated rice bags or even a hard boiled egg [2,6,14,15,21]. These methods have relatively unknown temperature behaviors, which establishes a rationale for the present study. ECPs note that patients are often noncompliant with the recommendations, which results in suboptimal and ineffective therapy leading to premature discontinuation of treatment [14]. This can make warm compress treatment frustrating for both ECPs and patients. Blackie et al. [16] reported reheating facecloths every 2 min to maintain a constant heat above 45 ◦ C for at least 4 min, to be effective for MGD. This would require a patient to be near a heating source (a sink or microwave oven) for the full 4 min, which may not always be convenient. To render some treatment options more patient-friendly and potentially improve compliance, several companies have developed commercially available warming eyelid masks that claim to maintain a constant temperature throughout the recommended 5–10 min [22–26]. Although commercially available eye masks have existed for a long time, these newer masks are taking into consideration the new knowledge of the temperature needed to soften the meibum, a fact that was not previously considered. Hence experimentation with different heat-retaining fillers for these eye masks has made them novel in the marketplace. It is of clinical interest to evaluate how well each of these eyelid masks retains the target temperature of 40–45 ◦ C over a 10-min interval. That being said, in order to remove the variability of eyelid thickness, tissue heat retention and distribution in human subjects, a control study was undertaken first. To that end, the objective of this ex vivo study was to evaluate and compare the heat retention properties of commercially available eyelid warming masks over a 12-min interval.
2. Materials and methods Five eyelid-warming masks and a warm facecloth (Table 1) were selected for this study to investigate their heat retention properties. The selected masks were the MGD Rx Eyebag® , The Eye Doctor® , Bruder eye hydrating compress, TranquileyesTM , Thera◦ Pearl® Eyeessential mask and a facecloth. To remove any influences from eyelid heat absorption, retention and distribution differences in human subjects, an ex vivo control study was performed using a non-conductive surface as a substrate. A 12 × 12 × 1 block of polystyrene rigid insulation board (Foamular® , CAN/ULC-S701, Type 3, CCMC 13431-L, Owens Corning, Canada) [27] was used due to its non-conductive properties and R-value of 5. An R-value is a measure of thermal resistance of a material or the capacity of a material to resist heat flow [28–30]. The R-value is used regularly in the construction industry to choose appropriate building materials that will reduce heating and cooling costs. Increasing R-values have greater insulating effectiveness and are typically more expensive [31]. For example, single pane glass, which is typically a poor insulator, has an R-value of 0.91. Softwoods, typically used for flooring, have R-values of up to 1.25. Blown fiberglass to insulate walls have an R-value between 3.7 and 4.3 depending on its thickness and polystyrene board (the substrate that was chosen for this study) has an R-value of 5.0 with a higher capacity to resist heat flowing through it. The experiment was conducted in a closed space protected from drafts. The
153
Fig. 1. Experiment arrangement (non-conductive 1 thick insulated polystyrene board, thermometer and evaluated mask).
room temperature and the insulator temperature were monitored to ensure environment stability. Each mask was left at ambient room temperature for several hours prior to the study. The temperature of each mask was then measured at 2 min (−2) and at 1 min (−1) prior to inserting in the microwave oven to establish baseline measures. Each eyelid mask was sequentially heated with a microwave oven following the manufacturer’s instructions. The same microwave oven was used for each procedure (Sharp Carousel 1100W). The eye mask was placed onto the Styrofoam board within 5–10 s of heating and its temperature was measured using a digital thermometer probe (Fisher Scientific Traceable Total-Range) placed underneath it, between the mask/cloth and the board, as shown in Fig. 1. The digital thermometer complies with ISO/IEC calibration and has a resolution of 0.1 ◦ C. Once the mask was placed on the board (time = 0), the temperature was measured at 1-min interval for 12 min. The procedure was repeated three times for each mask and the measurements were averaged and standard errors (SE) were calculated and plotted for comparison. The facecloth was heated using room temperature tap water heated for 20 s in the microwave oven to simulate hot tap water. The excess was wrung out, and the facecloth was folded to obtain three layers (to simulate an “at-home” procedure), and placed directly on the polystyrene board to be measured similarly to the other warming masks. Statistical analysis was performed using the nonparametric Mann–Whitney U-test at an alpha level of 0.05 using SPSS (version 17.0 for Windows). 3. Results Three trials per mask were recorded, averaged and plotted with standard error (SE) in Fig. 2. All masks reached a temperature above 40 ◦ C within the first minute, with the exception of the Thera◦ Pearl® which took 2 min. Three masks (MGDRx EyeBag® , The Eye Doctor® , Thera◦ Pearl® ) had the most stable heat retention over an 8-min interval, maintaining at the desired temperature of 40–45 ◦ C. The Bruder® and TranquileyesTM reached the highest temperatures of 54 ◦ C and 49 ◦ C, respectively within the first minute and maintained that temperature for the first 2 min before slowly decreasing. The Bruder® mask maintained a temperature above 50 ◦ C for the first 6 min and, although slowly decreasing afterwards, was not able to reach below 40 ◦ C at the 12-min mark. The TranquileyesTM maintained a temperature above 40 ◦ C for the first 4.5 min and subsequently held the targeted temperature for another 6 min. After the 10-min mark, TranquileyesTM fell below the desired range.
154
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
Table 1 Comparison of commercially available eyelid warming masks. Mask
Contents
MGDRx EyeBag® (The EyeBag Company)
Photo
Manufacturer instructions
Replacement
Flax seeds
Microwave for 30 s at full power (variable by microwave) Hold tips and gently shake to distribute heat
200 uses
32
The Eye Doctor® (The Body Doctor)
Mixed natural grains
Remove inner bag from cover Microwave inner bag for 30 s Hold tips and gently shake to distribute heat
150 uses
34
Bruder Eye Hydrating Compress (Bruder Healthcare)
MediBeads®
Microwave for 20 s Do not apply tightly
6 months if used daily
30
TranquileyesTM goggles (eyeeco)
Thermoeyes beads
Place beads gel pack in fabric pockets, place into net bag and microwave on high for 45 s in 1 cup of water Let stand for 1 min Remove from net and place gel packs and pocket into back of goggle
67
Thera◦ Pearl Eye-ssential mask (Bausch & Lomb)
Pearl Technology®
Microwave for 12 s
13
Warm facecloth
Aside from the facecloth, the TranquileyesTM mask lost heat quicker than any other mask. The facecloth, reached the targeted temperature quickly (within 1 min) and maintained it for only 3 min, subsequently degrading to 30 ◦ C within 10 min. The facecloth was significantly cooler than all other eyelid warming masks after the 4 min mark (p < 0.05 for all comparisons, respectively). The average ambient temperature and insulated surface temperature before measurement remained constant at 23.1 ◦ C and 22.5 ◦ C respectively. All masks were at room temperature prior to heating (time at −2 and −1 min mark in Fig. 2).
4. Discussion All eyelid warming masks increased in temperature following heating with the microwave oven. To be effective for MGD
Fold facecloth into 3 to create 3 layers Wet towel with hot (not burning) water
Manufacturer’s suggested retail price ($Cdn approx)
5
treatment the eyelid masks should reach target temperatures of 40–45 ◦ C [10,16] for several minutes, independent of the composition of its heat retaining elements. The facecloth is poor at retaining heat at the desired temperature for the required 5–10 min, which is typically recommended by ECPs for MGD therapy. This is not to take anything away from the time-honored warm facecloth therapy, which has shown to improve symptoms, the lipid layer and tear film stability [10,16,18,32]. Even Olson et al. [10] demonstrated that the lipid layer thickness was enhanced using a warm facecloth that was kept >38 ◦ C by reheating it every 2 min. With a better understanding of the therapeutic temperature needed to liquefy the meibum, a warm facecloth can still be advocated, but would have to be re-heated every 2 min, for a total of at least 4 min, to maintain a high enough temperature to affect the meibum in the inner meibomian glands [16]. Some eyelid warming masks require a microwave oven for heating with specific instructions on wattage and heating times,
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
155
Fig. 2. Average temperature (◦ C) of three trials ± SE reached for each eyelid warming mask over 12 min. Time 0 is immediately following the heating of the mask.
however patients are unlikely to change their appliance to comply with manufacturer’s instructions for an eyelid mask. This may result in potentially over or under heating the mask and affect its efficacy. In this study, the same microwave oven (1100 W) was used to heat each mask to standardize procedures, however that specific wattage may not have been appropriate for some masks. For example the MGDRx Eyebag® requires 30 s at full power, however this is variable depending on the wattage of the microwave oven. The Bruder® eye mask demonstrated the highest heat retention throughout the 12 min, with initial temperatures >50 ◦ C for the first 6 min after heating. These elevated temperatures have the potential to cause a first-degree contact burn to the skin surface of the eye. Fortuitously, the act of removing a mask from a microwave oven would alert the user if the mask was too hot to the touch and should avoid any potential for contact burns. Although the manufacturer’s recommendations of 20 s was followed for the Bruder® eye mask, it is plausible that the 1100 W microwave oven used in this study was too powerful, rendering it warmer than expected. Nonetheless, ECP need to remind patients to “test” any eyelid warming mask prior to placing it on the eyelid to prevent contact burns [33]. The contents of the warming eyelid masks used in this study (Table 1) vary from natural grains to specially developed heat beads, each with potentially differing heat retention properties. Some masks recommend replacement after a certain amount of uses. For example the Eye Doctor® advises a change after 150 uses. A therapy of twice a day would require a replacement every 2.5 months whereas a daily use would require a change in 5 months. Similarly, the MGDRx Eyebag® recommends a change every 200 uses, requiring a change every 3.3 months for twice a day therapy and 6 months for daily use. The recommendation to change the Bruder® is twice a year. The Thera◦ Pearl® has a washable plastic cover, which may render it more appealing to patients who want to clean their mask regularly from sweat, makeup and cream transferred from their face. Advantages of the facecloth are its availability, minimal costs and ease of washing. More importantly, there are still some people who do not possess a microwave oven, making the warm facecloth one of the only therapies available to them. The cost, reusability and availability of each mask will likely influence the ECP’s or the patient’s decision of which one is best suited for them. Emerging research and a better understanding of MGD should assist the ECPs in recommending therapeutically effective and evidence-based eyelid warming therapies to their patients. In addition to eyelid masks, promising new eyelid warming technologies include steam [17,19,34,35], thermal [36–39] and chemically activated disposable sachets [40]. Aside from the effect on the meibum,
warm compresses can also transiently degrade vision from the light pressure of the compress [41]. This study was an ex vivo study to assess the heat retention of different eyelid warming masks without the influence of the eyelid tissue. Ongoing clinical studies will compare the heat retention of different eyelid warming masks on participants, keeping in mind that different conduction properties of eyelid skin may be a factor to consider. To prevent over or under heating, manufacturers should consider including heating times according to microwave oven wattage. 5. Conclusion Heat retention profiles are different for commercially available eyelid warming masks. This study brings further awareness that the time-honored warm facecloth, which continues to be strongly recommended by ECP, is poor at retaining heat over a 5–10 min interval without reheating it at frequent intervals. ECPs should educate patients/staff about the differences of commercially available eyelid warming masks, and alter their instructions with respect to the facecloth to maintain a therapeutically effective temperature. Ineffective therapy due to poor heat retention may lead to discouragement and discontinuation of treatment. Conflict of interest None of the authors have any financial interests with any of the products mentioned. Acknowledgments The authors would like to thank W. Wittich for statistical analysis and M. Gloin for assistance with graphics. References [1] The definition and classification of dry eye disease: report of the definition and classification subcommittee of the international dry eye workshop. Ocul Surf 2007;5(2):75–92. [2] Bron AJ, Tiffany JM. The contribution of meibomian disease to dry eye. Ocul Surf 2004;2(2):149–64. [3] Foulks GN, Bron AJ. Meibomian gland dysfunction: a clinical scheme for description, diagnosis, classification, and grading. Ocul Surf 2003;1(3): 107–26. [4] Hom M, Martinson J, Knapp L, Paugh J. Prevalence of meibomian gland dysfunction. Optom Vis Sci 1990;67(9):710–2.
156
Z. Lacroix et al. / Contact Lens & Anterior Eye 38 (2015) 152–156
[5] Hykin P, Bron A. Age-related morphological changes in lid margin and meibomian gland anatomy. Cornea 1992;11:334–42. [6] Kanski J, Bowling B. Eyelids. In: Clinical ophthalmology: a systemic approach. 7th ed. Edinburgh: Elesvier Saunders; 2011. p. 2–37. [7] Knop E, Knop N, Millar T, Obata H, Sullivan DA. The international workshop on meibomian gland dysfunction: report of the subcommittee on anatomy, physiology, and pathophysiology of the meibomian gland. Invest Ophthalmol Vis Sci 2011;52(4):1938–78. [8] Linton R, Curnow D, Riley W. The meibomian glands: an investigation into the secretion and some aspects of the physiology. Br J Ophthalmol 1961;45(7):18–23. [9] Terada O, Chiba K, Senoo T, Obara Y. Ocular surface temperature of meibomia gland dysfunction patients and the melting point of meibomian gland secretions. Nihon Ganka Gakkai Zasshi 2004;108:690–3. [10] Olson M, Korb D, Greiner J. Increase in tear film lipid layer thickness following treatment with warm compresses in patients with meibomian gland dysfunction. Eye Contact Lens 2003;29(2):96–9. [11] Bron A, Tiffany J, Gouveia S, Yokoi N, Voon L. Functional aspects of the tear film lipid layer. Exp Eye Res 2004;78:347–60. [12] King-Smith P, Nichols J, Nichols K, Fink B, Braun R. Contributions of evaporation and other mechanisms to tear film thinning and breakup: a review. Optom Vis Sci 2008;85:623–30. [13] Kimball S, King-Smith E, Nichols J. Evidence for the major contribution of evaporation to tear film thinning between blinks. Invest Ophthalmol Vis Sci 2010;51(12):6294–7. [14] Geerling G, Tauber J, Baudouin C, Goto E, Matsumoto Y, O’Brien T, et al. The international workshop on meibomian gland dysfunction: report of the subcommittee on management and treatment of meibomian gland dysfunction. Invest Ophthalmol Vis Sci 2011;52(4):2050–64. [15] Blepharitis/meibomitis.Gertenbilth A, Rabinowitz M, editors. The Wills eye manual: office and emergency room diagnosis and treatment of eye disease. 6th ed. Philadelphia Wolters Kluwer: Lippincott Williams & Wilkins; 2012. p. 125. [16] Blackie C, Solomon J, Greiner K, Holmes M, Korb D. Inner eyelid surface temperature as a function of warm compress methodology. Optom Vis Sci 2008;85(8):675–83. [17] Pult H, Riede-Pult BH, Purslow C. A comparison of an eyelid-warming device to traditional compress therapy. Optom Vis Sci 2012;89(7): 1035–41. [18] Goto E. Improvement of tear stability following warm compression in patients with meibomian gland dysfunction. Cornea 2000;19(6):90. [19] Matsumoto Y, Dogru M, Goto E, Ishida R, Kojima T, Onguchi T, et al. Efficacy of a new warm moist air device on tear functions of patients with simple meibomian dysfunction. Cornea 2006;25:644–50. [20] Mori A, Shimazaki J, Shimmura S, Fujishima H, Oguchi Y, Tsubota K. Disposable eyelid-warming device for the treatment of meibomian gland dysfunction. Jpn J Opthalmol 2003;47:578–86. [21] Freedman H, Preston K. Heat retention in varieties of warm compresses: a comparison between warm soaks, hard-boiled eggs and the re-heater. Ophthalmol Surg 1989;20:846–8.
[22] Narayan R. Meibomian gland dysfunction. Optician 2012;3(8):16–21. [23] TheEyeBagCompany. MGDRx EyeBag; 2013. Available from: http://www. eyebagcompany.com/ [accessed 15.11.13]. [24] Bruder. Moist Heat Compresses; 2013. Available from: http://www.bruder. com/eye/products/ [accessed 15.11.13]. [25] TheBodyDoctor. The Eye Doctor; 2013. Available from: http://www.the-bodydoctor.com/the-eye-doctor [accessed 15.11.13]. [26] eyeeco. tranquileyes; 2013. Available from: http://www.eyeeco.com/ [accessed 15.11.13]. [27] Extruded Polystyrene Rigid Insulation [Internet]. OWENS CORNING CANADA LP; 2011. Available from: http://insulation.owenscorning.ca/assets/0/188/ 9005b9ef-1bb5-469c-b0c2-9540c3aa4108.pdf [28] Insulation: U.S. Department of Energy; 2012. Available from: http://energy.gov/ energysaver/articles/insulation [accessed 15.12.14]. [29] R-values of Insulation and Other Building Materials: Arch Media Group LLC; 2014. Available from: http://www.archtoolbox.com/materials-systems/ thermal-moisture-protection/rvalues.html [accessed 15.12.14]. [30] R-Value: North American Insulation Manufacturers Association; 2014. Available from: http://www.naima.org/glossary/entry.php?entryID=23 [accessed 15.12.14]. [31] R-Value Table: Insulation Values For Selected Materials: Colorado Energy; 2014. Available from: http://www.coloradoenergy.org/procorner/stuff/ r-values.htm [accessed 15.12.14]. [32] Paugh J, Knapp L, Martinson J, Hom M. Meibomian therapy in problematic contact lens wear. Optom Vis Sci 1990;67:803–6. [33] Alden N, Rabbitts A, Yurt R. Contact burns: is further prevention necessary? J Burn Care Res 2006;27(4):472–5. [34] Mitra M, Menon G, Casini A. Tear film lipid layer thinkcness and ocular comfort after meibomian therapy via latent heat with a nivel device in normal subjects. Eye 2005;19:657–60. [35] Spiteri A, Mitra M, Menon G. Tear lipid layer thickness and ocular comfort with a novel device in dry eye patients with and without Sjogren’s syndrome. J Fr Ophthalmol 2007;30:357–64. [36] Greiner J. Long-term (12-month) improvement in meibomian gland function and reduced dry eye symptoms with a single thermal pulsation treatment. Clin Exp Ophthalmol 2013;41(6):524–30. [37] Korb D, Blackie C. Case report: a successful LipiFlow treatment of a single case of meibomian gland dysfunction and dropout. Eye Contact Lens 2013;39(3):e1–3. [38] Greiner J. A single LipiFlow® thermal pulsation system treatment improves meibomian gland function and reduces dry eye symptoms for 9 months. Curr Eye Res 2012;37:272–8. [39] Lane S, DuBiner H, Epstein R, Ernest P, Greiner J, Hardten D, et al. A new system, the LipiFlow, for the treatment of meibomian gland dysfunction. Cornea 2012;31(4):396–404. [40] Sim H, Petznick A, Barbier S. A randomized, controlled treatement trial of eyelid warming therapies in meibomian gland dysfuntion. Ophthalmol Ther 2014;3:37–48. [41] Solomon J, Case C, Grenier J, Blackie C, Herman J, Korb D. Warm compress induced visual degradation and Fischer–Schweitzer polygonal reflex. Optom Vis Sci 2007;84:580–7.
