1040-5488/13/9009-0945/0 VOL. 90, NO. 9, PP. 945Y953 OPTOMETRY AND VISION SCIENCE Copyright * 2013 American Academy of Optometry
ORIGINAL ARTICLE
Comfort Response of Three Silicone Hydrogel Daily Disposable Contact Lenses Jalaiah Varikooty*, Nancy Keir†, Doris Richter‡, Lyndon W. Jones§, Craig Woods||, and Desmond Fonn**
ABSTRACT Purpose. To evaluate subjective ocular comfort across the day with three silicone hydrogel daily disposables (SHDDs) in a group of adapted lens wearers. Methods. Masked subjects (asymptomatic or symptomatic of end-of-day (EOD) dryness with habitual lenses) wore three SHDDs: DAILIES TOTAL1 (DT1), Clariti 1day (C1D), or 1-DAYACUVUE TRUEYE (AVTE), each for 3 days. On day 2, wearing time (WT) and comfort ratings after insertion, at 4, 8, and 12 hours, and at EOD were recorded. Because not all subjects wore lenses for 12 hours, comfort was analyzed across the day (up to 8 hours, 8 to 12 hours), and a new variable (‘‘cumulative comfort’’ [CC]) was calculated for EOD. Results. One hundred four subjects completed the study (51 asymptomatic, 53 symptomatic). The two groups had different WTs (mean WT, 14.0 and 12.7 hours, respectively; p G 0.001). Ocular comfort was rated higher in the asymptomatic group throughout the day (p G 0.001). One hundred four subjects wore all three SHDDs for at least 8 hours, whereas 74 (45 asymptomatic, 29 symptomatic) subjects wore them for 12 hours or longer. Comfort ratings were higher with DT1 (least square means [LSM] = 91.0) than with C1D (LSM = 86.5; p G 0.001) and AVTE (LSM = 87.7; p = 0.011) for the first 8 hours and lower with C1D compared with DT1 (p = 0.012) from 8 to 12 hours. Mean EOD (T SD) comfort with the C1D lens was 72 T 21, lower than both DT1 (mean, 79 T 17; p = 0.001) and AVTE (mean, 78 T 21; p = 0.010). Mean CC was higher in the asymptomatic group (mean, 1261 T 59) compared with that in the symptomatic group (mean, 1009 T 58; p G 0.001) and higher for DT1 (mean, 1184 T 258) than C1D (mean, 1094 T 318; p = 0.002) and AVTE (mean, 1122 T 297; p = 0.046). Conclusions. All three SHDDs had average WTs of 12 hours or longer for 1 day. Comfort during the first 12 hours was highest with DT1 (similar to AVTE between 8 and 12 hours) and lowest with C1D. End-of-day comfort was lowest with C1D, and CC was highest for DT1. Cumulative comfort may be a valuable new metric to assess ocular comfort during the day. (Optom Vis Sci 2013;90:945Y953) Key Words: contact lens, silicone hydrogels, daily disposable, comfort
C
ontact lens patients complain of ocular dryness and discomfort at the end of the day (EOD) with their contact lenses, despite the development of new contact lens products during the past decade to mitigate these symptoms.1,2 Discomfort and dryness associated with lens wear continue to be an important issue, as reflected by the high annualized number of contact lens dropouts, with discomfort consistently being the *MBBS, MSc † OD, PhD, FAAO ‡ OD, MASc § PhD, FCOptom, FAAO || PhD, MCOptom, FAAO **MOptom, FAAO Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada (JV, NK, DR, LWJ, DF); and School of Medicine (Optometry), Deakin University, Waurn Ponds, Victoria, Australia (CW).
primary driver.2Y5 Efforts to address symptoms of ocular discomfort and dryness that worsen toward the EOD4,6 have included the development of contact lens materials that exhibit low levels of on-eye dehydration,7 lens materials and blister-pack solutions that incorporate components to enhance wettability, such as polyvinyl alcohol8 and polyvinyl pyrrolidone,9 disinfecting solutions incorporating various surfactants and wetting agents,10,11 and rewetting drops and tear substitutes containing hydrophilic polymers and other substances such as hyaluronic acid.12 The high level of convenience, increased compliance with replacement frequency,13,14 reduced deposition, and an absence of lens care and the associated solution-induced corneal staining,15,16 along with their reduced number of clinical complications,17,18 are some of the possible reasons resulting in an ever-increasing number of patients being fitted with daily disposable contact lenses.19 Until recently, however, daily disposable contact lenses were only
Optometry and Vision Science, Vol. 90, No. 9, September 2013
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946 Comfort and Hydrogel Daily Disposable Contact LensesVVarikooty et al.
available in nonsilicone hydrogel materials, lacking the physiological benefits of higher levels of oxygen transmissibility provided by silicone hydrogel materials. This situation has changed through the introduction of the silicone hydrogel daily disposable (SHDD) lens materials: narafilcon A and B (1-DAY ACUVUE TRUEYE [AVTE]; Johnson & Johnson Vision Care, Inc.),20 filcon II 3 (Clariti 1day [C1D]; Sauflon Pharmaceuticals Ltd.),21 and delefilcon A (DAILIES TOTAL1 [DT1]; Alcon Laboratories, Inc.).19,22 Silicone hydrogel daily disposables have been recently introduced, and studies reporting the ocular comfort experienced with the use of these lenses are relatively sparse compared with SH frequent replacement lenses.16,17,21,23,24 Therefore, the objective of this study was to measure ocular comfort for 1 day in asymptomatic and symptomatic subjects who each wore three different SHDD lenses.
METHODS The study was conducted as a prospective, randomized, bilateral, crossover trial. Complete masking of the investigators was not possible because they may have recognized lens design features or markings while evaluating lenses on-eye. Subjects were completely masked, however, by overlabeling the lens blister packs, and current wearers of SHDD lenses were excluded from the study, which meant that none of the subjects had previous experience with any of the study lenses. In addition, the identity of the sponsor (Alcon Laboratories, Inc.) was not disclosed until the end of the study. The eligibility of subjects was determined through a screening assessment, which included biomicroscopy, a lens-fitting assessment, and a questionnaire on the frequency (0 = never, 4 = constantly) and intensity (0 = never have it, 5 = very intense) of late day dryness, modeled after the Contact Lens Dry Eye Questionnaire.6 Subjects were adapted soft contact lens wearers and were free of ocular and/or systemic disease that could impact contact lens wear. In addition, subjects needed to achieve a clinically acceptable fit with each of the study lenses to be eligible. Ethics clearance was obtained through the Office of Research
Ethics at the University of Waterloo, and each subject underwent an informed consent process before entering the study. All subjects were treated in accordance with the tenets of the Declaration of Helsinki, and the study was conducted according to Good Clinical Practice Guidelines. Once eligibility was confirmed, subjects were assigned to either an asymptomatic or symptomatic group on the basis of their response to the frequency and intensity of late day dryness during the past week. The grouping assignment followed the classification proposed by Young et al.25 Fig. 1 describes the study design, and lens details are provided in Table 1. Subjects wore all three study lenses, with the order of lens wear being randomized. There was at least a 1-day break between wearing of each study lens, when subjects could choose to wear either their spectacles or habitual contact lenses. Study lenses were dispensed before each study phase according to the subject’s randomization and worn for three consecutive days of daily disposable wear. Subjects inserted the study lenses directly from the blister pack and were advised to refrain from using any artificial tears during the study. Assessments were made at the Centre for Contact Lens Research on day 1, in the morning when lenses were dispensed, and after 8 hours of wear, and also on day 3, after 8 hours of wear. On day 2, there were no clinical assessments, so subjects had a full day of lens wear, uninterrupted by in-office assessments, during which they rated comfort across the entire day. A post hoc analysis of the day 2 at-home ratings is reported in this article. At-home ratings on day 2 were recorded promptly after lens insertion and then every 4 hours and immediately before lens removal. Ratings were recorded on paper and brought to the appointment at the following visit. Insertion and removal times were recorded, and comfort was rated using a 0 (‘‘very poor’’) to 100 (‘‘excellent’’) visual analog scale. Compliance was not monitored; however, clear instructions were provided and subjects were asked to report the time each rating was recorded. Instructions also advised subjects to wear the study lenses for as long as they were able and to remove them when they normally would or when they became uncomfortable and always before overnight
FIGURE 1. Study design and lenses. Optometry and Vision Science, Vol. 90, No. 9, September 2013
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Comfort and Hydrogel Daily Disposable Contact LensesVVarikooty et al.
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TABLE 1.
Lens parameters Lens properties Manufacturer/supplier Lens name Material FDA contact lens material group Water content Dk/t value (j3.00 D) Diameter, mm BCOR, mm Modulus, MPa Power (DSph) (0.25 steps) Stated central thickness, mm @ j3.00 D
Alcon Laboratories, Inc. DAILIES TOTAL1 delefilcon A Group I 33% in the core of the lens and 980% at the surface† 156 14.1 8.5 0.7 (lens core) j1.00 to j6.00 0.090
Sauflon Clariti 1Day filcon II 3 Group II* 56%
Johnson & Johnson Vision Care 1-DAY ACUVUE TruEye narafilcon A Group I 46%
86 14.1 8.6 0.5 j1.00 to j6.00 0.070
118 14.2 8.5, 9.0 0.66 j1.00 to j6.00 0.085
*Group II designation assumed based on material properties (nonionic, high water polymer) and not on FDA clearance or approval. No publicly available USAN name. †As reported by Alcon Laboratories, Inc.
sleep. The end of wear comfort reported just before lens removal is often referred to as ‘‘end-of-day comfort’’ in the published literature26,27, and for consistency, we will also refer to the end of wear as EOD. As the lens removal time occurred at different times for subjects with each of the study lenses, post hoc analysis was done and a new variable termed ‘‘cumulative comfort’’ (CC) was developed to incorporate the wearing time (WT) into the interpretation of EOD comfort. The CC score was calculated by summing the comfort scores for each hour of lens wear. This was estimated using the ratings that were completed every 4 hours until the removal time was reached and by assuming that the comfort rating for the hours before the rating time point were equivalent. The EOD rating was used for the remaining hours. As an example, if someone was only able to wear his or her lenses for 10 hours, the CC score would be 4*VAS@4hrs + 4*VAS@8hrs + 2*VAS@ EOD, where VAS stands for ‘‘visual analog scale score.’’ The resulting score can be roughly interpreted by considering that every 100 units represent the equivalent of 1 hour of ‘‘perfect comfort.’’ However, some care needs to be taken with respect to this interpretation because it is possible to arrive at the same score in different scenarios; for instance, 2 hours of lens wear with a comfort rating of 50 would also yield a CC score of 100 units. Data were analyzed using Statistica 10,28 with the goal of determining whether there were any differences between lenses or symptomatic groups with respect to comfort across the day. Analysis of variance and Tukey post hoc testing were conducted for comfort ratings with the following factors: group (asymptomatic and symptomatic), lens (three levels within subject), and time point (including all time points with complete data except EOD). Because the comfort ratings for EOD were complicated by the fact that these ratings occurred at different times of the day with different lenses, EOD and CC were analyzed using post hoc methods. The EOD comfort ratings and CC scores were analyzed using analysis of variance and Tukey post hoc testing, with group and lens as factors. The least square means (LSMs) are reported. The statistical significance level was set at p G 0.05, with no
adjustments for multiplicity. Descriptive statistics have also been reported.
RESULTS A total of 119 subjects were enrolled in the study. Fifteen subjects discontinued from the study because of either personal inconvenience or nonYstudy-related reasons. Therefore, 104 subjects completed the study (75 female, 29 male) and were included in the analysis. The mean age of the 104 subjects was 27 T 9 years (median, 23 years; ranging from 17 to 51 years). There were 51 subjects in the asymptomatic group and 53 subjects in the symptomatic group. Twenty-three percent of subjects typically wore their habitual lenses for 14 hours or more (eight in the symptomatic group and 16 in asymptomatic group). The type of habitual lens and habitual wearing modality of the subjects are described in Tables 2 and 3. The mean comfort ratings (TSD) at each time point on day 2 of the study are summarized in Table 4. The EOD comfort ratings occurred at the end of the WT for each subject, not at a specific time point. The distribution of WTs ranged from 9 to 19 hours in the asymptomatic group and from 7 to 18 hours in the symptomatic group, as shown in Fig. 2. The mean WT, including all three lens materials, was 14.0 hours
TABLE 2.
Summary of habitual lens types worn Percentage of subjects Habitual lens Hydrogel lenses Silicone hydrogel lenses
Daily disposables
Frequent replacement
25 0
18 57
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948 Comfort and Hydrogel Daily Disposable Contact LensesVVarikooty et al. TABLE 3.
Percent of participants for each habitual lens brand Habitual lens brand ACUVUE OASYS with HYDRACLEAR PLUS AIR OPTIX NIGHT & DAY AQUA ACUVUE ADVANCE with HYDRACLEAR Focus NIGHT & DAY PureVision Focus DAILIES 1-DAY ACUVUE MOIST Proclear 1 Day ACUVUE 2 encore100 FreshLook COLORBLENDS SofLens daily disposable Other brands
%
Replacement schedule
Material
30 15 6 3 3 7 5 5 4 3 3 2 14 (all 1% or less for each lens brand)
2 weeks 1 month 2 weeks 1 month 1 month DD DD DD 2 weeks 1 month 2 weeks DD DD, 2 weeks and 1 month
Silicone hydrogel Silicone hydrogel Silicone hydrogel Silicone hydrogel Silicone hydrogel Hydrogel Hydrogel Hydrogel Hydrogel Hydrogel Hydrogel Hydrogel All Hydrogel
for the asymptomatic group and 12.7 hours for the symptomatic group; this difference was statistically significant (p G 0.001).
The First 8 Hours Fig. 3 shows the comfort ratings for time points up to 8 hours for all 104 subjects (51 asymptomatic, 53 symptomatic). When EOD occurred between 7 and 8 hours, these data were included as 8-hour data. On average, the comfort ratings were higher in the asymptomatic group (LSM = 92.0) than in the symptomatic group (LSM = 85; p G 0.001). In the symptomatic group for all lenses combined, the mean comfort rating at 8 hours was lower than at insertion and at 4 hours (both p G 0.001). The overall mean comfort rating with the DT1 lens (LSM = 91.0) was higher than that with C1D (LSM = 86.5; p G 0.001) and AVTE (LSM = 87.7; p = 0.011) lenses; however, there was no statistically significant difference between C1D and AVTE (p 9 0.05) lenses.
Between 8 and 12 Hours Seventy-four subjects (45 asymptomatic, 29 symptomatic) wore all three lens materials for at least 12 hours. The change in comfort ratings from 8 to 12 hours is shown in Fig. 4 for these subjects. The remaining 30 subjects did not reach 12 hours of lens wear for one or more of the lens materials, and the number of
subjects removing their lens before 12 hours is shown in Fig. 5. For all lenses combined, comfort ratings were lower in the symptomatic group (LSM = 80.0) compared with that in the asymptomatic group (LSM = 90.0; p G 0.01), and there was a significant difference between comfort ratings at 8 hours as compared with 12 hours (p G 0.01). For both groups combined, ocular comfort was rated lower with the C1D lens (LSM = 84.0) compared with the DT1 lens (LSM = 88.0; p = 0.012). There was no statistically significant difference in comfort rated between the DT1 lens and the AVTE lens (LSM = 85.0; p 9 0.05).
EOD Comfort and CC Score The mean EOD comfort ratings (TSD) for all 104 subjects are shown in Table 4. For all lenses combined, the EOD comfort ratings (mean T 95% confidence interval) were lower in the symptomatic group (69 T 4) compared with those in the asymptomatic group (84 T 4; p G 0.001). Overall, the mean EOD comfort rating for the C1D lens (72 T 4) was lower than those for both the DT1 (79 T 3; p = 0.001) and AVTE (78 T 4; p = 0.010) lenses. There was no statistically significant difference in EOD comfort between the DT1 and AVTE lenses (p 9 0.05). In studies where WTs or reasons for lens removal are not specified, EOD comfort alone may not be an appropriate metric for assessing lens performance in relation to ocular comfort. In this study, for example, although the mean EOD comfort was lower
TABLE 4.
Ratings of comfort at insertion, at 4 hours, 8 hours, and 12 hours, and at EOD (Day 2) Mean T SD Lens
Insertion
4h
8h
12 h
EOD
Asymptomatic group, n = 51 except at 12 h
DAILIES TOTAL 1 Clariti 1day 1-DAY ACUVUE TRUEYE
93 T 9 91 T 12 89 T 18
95 T 9 93 T 10 93 T 10
93 T 10 90 T 12 91 T 11
89 T 14, n = 49 85 T 16, n = 48 88 T 15, n = 47
84 T 16 81 T 18 86 T 15
Symptomatic group, n = 53 except at 12 h
DAILIES TOTAL1 Clariti 1day 1-DAY ACUVUE TRUEYE
91 T 10 88 T 12 89 T 12
90 T 9 83 T 12 85 T 16
84 T 12 75 T 19 79 T 19
79 T 16, n = 45 71 T 18, n = 40 76 T 17, n = 38
74 T 16 63 T 20 70 T 22
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Comfort and Hydrogel Daily Disposable Contact LensesVVarikooty et al.
949
FIGURE 2. Wearing times for the asymptomatic and symptomatic groups.
when subjects wore the C1D lens than that when subjects wore the AVTE, arithmetically, more subjects wore the C1D lens for at least 12 hours. This raises the interesting question that if subjects wear their lenses longer, but end up with a lower EOD comfort score, does this mean the performance of this lens was worse than
a lens that had a higher EOD comfort score but was removed earlier? Given that subjects in this study were permitted to remove lenses before the 12-hour time point, early removal of a select lens material (or materials) might in fact be an indicator of discomfort. Although the reason for lens removal was not captured
FIGURE 3. Mean comfort ratings for first 8 hours (T95% confidence interval). Optometry and Vision Science, Vol. 90, No. 9, September 2013
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950 Comfort and Hydrogel Daily Disposable Contact LensesVVarikooty et al.
FIGURE 4. Mean comfort ratings between 8 and 12 hours for subjects who wore all lenses at least 12 hours (T95% confidence interval); asymptomatic group, n = 45; symptomatic group, n = 29.
in this study, each participant wore all three SHDDs; therefore, the overall typical behavior (i.e., routinely removing before bed during a standard work week) should have been similar for each lens material or, alternatively, different behaviors would have resulted in random effects because the order of lenses were
randomized. As a result of the differences in WTs, post hoc CC scores were calculated, and results are shown in Fig. 6. The mean CC score was lower in the symptomatic group (1009 T 58) compared with that in the asymptomatic group (1261 T 59; p G 0.001) and was lower for both the C1D (1094 T 318; p = 0.002)
FIGURE 5. Number of subjects removing lenses before 12 hours. Optometry and Vision Science, Vol. 90, No. 9, September 2013
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FIGURE 6. Mean cumulative comfort for the asymptomatic and symptomatic groups (T95% confidence interval).
and AVTE (1122 T 58; p = 0.046) lenses than for the DT1 lens (mean, 1184 T 50). The difference in CC between the AVTE and C1D lenses was not statistically significant (p 9 0.05).
DISCUSSION Silicone hydrogel daily disposable contact lenses were introduced in 2009, and relatively few studies have been published todate regarding their performance,16 particularly regarding ocular comfort toward the end of the lens-wearing period. This study reports ocular comfort with three SHDD lens materials in adapted lens wearers who are asymptomatic and symptomatic for EOD dryness with their habitual lenses. The results indicate that subjects experience good ocular comfort with all three lenses, with the lowest mean comfort rating being 71 units (out of 100) at 12 hours in the symptomatic group. The difference in mean comfort between the three lenses was about three to four points on a 0 to 100 scale, and the DT1 was rated slightly higher than the other two study lenses. Although the clinical relevance of this slight difference could be debated,29 the optimal methods for deriving clinical significance for ocular comfort remain to be properly established. However, consistent with other soft lens studies,4,30,31 all three SHDD lenses were associated with a decline in ocular comfort across the day. The comfort ratings at 12 hours may be somewhat biased because ratings were not reported by 30 participants who did not wear lenses for this length of time. If these participants were required to wear lenses for 12 hours or more, it is possible that the 12-hour comfort rating with all 104 subjects might have been lower. Although not recorded in this study, the reason for lens removal would have been useful, and it would have been interesting to know whether any of the subjects who were originally classified as
symptomatic with their habitual contact lenses would have been classified as marginally symptomatic or asymptomatic after wearing any of the SHDDs. Ideally, future studies would include this information. In addition to differences in ocular comfort between the symptomatic and asymptomatic groups, which were not unexpected, there were also differences in WT. A greater number of subjects in the asymptomatic group wore their lenses for 12 hours or more compared with the symptomatic group. This may indicate that the behavior of subjects with respect to their WT is dependent on the comfort of the lens. ‘‘End-of-day comfort’’ is typically defined as the comfort experienced just before lens removal, which is related to the total WT. Clinical trials reporting contact lensYrelated symptoms of comfort and dryness have mainly focused on mean and overall symptoms and report the mean WT, which has typically varied between 12 and 16 hours.6,8,32,33 However, these reports do not specifically assess the impact of WT on overall or EOD ocular comfort. When WT was taken into consideration in this study using post hoc analysis to provide a CC score, the comfort was rated significantly higher for longer periods with the DT1 lens compared with those for both the C1D and AVTE. Although there may be different approaches to account for the impact of WT on ocular comfort, we feel that this is an interesting new comfort parameter that provides a better understanding of changes in ocular comfort at the EOD and is a valuable way of comparing the relative performance of lenses across the day. In future studies, additional information collected at EOD, such as the reason for lens removal, may also aid in the interpretation of EOD and CC. Many factors can influence ocular comfort. Clinical findings associated with the three SHDDs investigated (i.e., visual acuity, lens wettability, lens deposition, and biomicroscopy) are the subject of another manuscript under preparation; however, nonYlens-related
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952 Comfort and Hydrogel Daily Disposable Contact LensesVVarikooty et al.
factors such as the environment, ocular health, and dry eye and lensrelated factors such as material properties, subtle differences in lens design, and lens parameters may have all played a role. Although all three lenses are manufactured from siloxane-based materials, each lens has its own unique features. The AVTE material is embedded with a moisturizing and wetting agent, polyvinyl pyrrolidone, through a proprietary Hydraclear 1 technology to improve moisture retention and lubricity of the lens without any additional surface coating or treatment.22 The C1D lens manufacturing process includes a proprietary AquaGen technology intended to enhance the wettability of the lens material,21 and the DT1 lens is manufactured through a proprietary LightStream process and has a unique water content gradient that varies from 33% in the core of the lens to more than 80% at the lens surface22 to provide increased surface lubricity. In a recent in vitro study comparing all three of these lenses, DT1 exhibited a lower amount of in vitro bulk dehydration compared with those for AVTE and C1D34; however, to our knowledge, there have been no other published reports comparing these three lenses. In summary, the three SHDD lenses investigated in this study resulted in reasonably high levels of ocular comfort and long average WTs (Q12 hours) in adapted lens wearers, approximately 50% of whom were symptomatic with their habitual non-SHDD lenses. Combined with the high oxygen transmissibility of silicone hydrogel materials and the convenience and other benefits of a daily disposable modality, SHDDs are a valuable option for practitioners to consider for their patients. Generally, comfort during the first 12 hours was highest with the DT1 lens (similar to the AVTE lens between 8 and 12 hours) and was lowest with the C1D lens during 1 day of lens wear. End-of-day comfort was lowest with the C1D lens, and CC was highest for the DT1 lens. Further studies are necessary to determine whether these findings continue to hold up after longer periods of wear.
ACKNOWLEDGMENTS Financial support for this study was provided by Alcon Laboratories, Inc. Received December 10, 2012; accepted May 6, 2013.
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Jalaiah Varikooty Centre for Contact Lens Research University of Waterloo 200 University Ave West Waterloo Ontario Canada N2L 3G1 e-mail:
[email protected]
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