Publications by authors named "Kathryn A Dumbleton"

8 Publications

  • Page 1 of 1

Diurnal Variation in Comfort in Contact Lens and Non-contact Lens Wearers.

Optom Vis Sci 2016 08;93(8):820-7

*PhD, FAAO †BSc(Hons), MSc ‡BSc(Hons) OCULAR TECHNOLOGY GROUP-International London, United Kingdom (KD, MG, PT, TP); and School of Life and Health Science, Aston University, Birmingham, United Kingdom (MG).

Purpose: The purpose of this investigation was to evaluate the diurnal variation in symptoms associated with ocular discomfort in contact lens (CL) wearers and non-CL wearers.

Methods: The study population comprised 604 individuals attending pre-screening visits at the OTG-i research clinic; 60% were current soft CL wearers (hydrogel and silicone hydrogel) and 40% were non-CL wearers. Symptomatology status was determined by the OSDI questionnaire (58% asymptomatic, 42% symptomatic). Participants were asked to grade their comfort, vision, and other symptoms during the day and in the evening (before lens removal for CL wearers) on 0 to 100 visual analogue scales.

Results: Diurnal decrease in comfort was significantly greater for CL wearers (-16.0 vs. -6.3, p < 0.001) and symptomatic participants (p = 0.015). Diurnal decrease in subjective vision was also significantly greater for CL wearers (-10.4 vs. -6.9, p = 0.005) and symptomatic participants (p = 0.001), and the interaction between these factors was also significant (p = 0.019). Dryness, grittiness, and irritation increased significantly more for CL wearers (p < 0.001, p = 0.012, and p = 0.004, respectively) and grittiness, irritation, and stinging for symptomatic participants (p = 0.016, p < 0.001, and p < 0.001, respectively). For the CL wearers, there was a significant interaction between dryness and age (p = 0.026) with the diurnal increase in dryness being greater in those under 40 (+15.6 vs. +10.0).

Conclusions: The diurnal decrease in comfort and subjective vision, and the diurnal increase in dryness, grittiness, and irritation, were significantly more marked for CL wearers than non-CL wearers. Diurnal changes in comfort, grittiness, stinging, irritation, and vision were influenced by the subject's overall symptomatology as assessed by the OSDI questionnaire. For dryness symptoms, the diurnal decrease was most marked in young CL wearers. For the symptoms of stinging and vision, the diurnal changes were most pronounced in the symptomatic groups.
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http://dx.doi.org/10.1097/OPX.0000000000000920DOI Listing
August 2016

Association Between Contact Lens Discomfort and Pre-lens Tear Film Kinetics.

Optom Vis Sci 2016 08;93(8):881-91

*PhD, FAAO †BSc(Hons), MSc ‡BA, BSc(Hons) §BSc(Hons) ∥MSTOptom OCULAR TECHNOLOGY GROUP-International, London, United Kingdom (MG, KD, BT, BW, KP, GB, TP); and School of Life and Health Science, Aston University, Birmingham, United Kingdom (MG).

Purpose: The relationship between contact lens wettability and comfort has been extensively evaluated; however, a direct correlation between the characteristics of the pre-lens tear film and the symptoms associated with contact lens discomfort has yet to be established. In addition, there is relatively limited knowledge relating to the entire tear film kinetics during the inter-blink period in contact lens wearers. The purpose of this analysis was to identify the characteristics of the pre-lens tear film kinetics that may be associated with the symptoms of contact lens discomfort.

Methods: The study population comprised 202 soft (hydrogel and silicone hydrogel) contact lens wearers attending pre-screening visits at the OTG-i research clinic. All participants completed the Ocular Surface Disease Index (OSDI) questionnaire and the tear film was quantified via post hoc, masked analysis of high definition digital Tearscope videos recorded at the visit. The tear film kinetics of the least symptomatic wearers (OSDI lowest quintile scores, n = 45) were compared to the tear film kinetics of the most symptomatic wearers (OSDI highest quintile scores, n = 43). The hypothesis tested was that the tear film kinetics of asymptomatic wearers were better than tear film kinetics of symptomatic wearers.

Results: The distribution of lens types worn was as follows: Daily Disposable 46.5%, 1-Month Replacement 39.6%, and 2-Week Replacement 13.6%. 48.2% of lenses were silicone hydrogel and 51.8% hydrogel. Symptomatic wearers had a shorter break-up time (4.7 s vs. 6.0 s; p = 0.003), lesser surface coverage by the tear film during the interblink period (95.1% vs. 98.5%; p < 0.001) and greater surface exposure at the time of the blink (9.4% vs. 3.9%; p = 0.001).

Conclusions: The current study demonstrated that the tear film kinetics of asymptomatic and symptomatic contact lens wearers were different, the findings supporting the hypothesis of poorer tear film kinetics for symptomatic than asymptomatic wearers in a general contact lens wearing population.
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http://dx.doi.org/10.1097/OPX.0000000000000866DOI Listing
August 2016

A multi-country assessment of compliance with daily disposable contact lens wear.

Cont Lens Anterior Eye 2013 Dec 8;36(6):304-12. Epub 2013 Jul 8.

Centre for Contact Lens Research, University of Waterloo, Waterloo, Ontario, Canada. Electronic address:

Purpose: To investigate compliance with daily disposable contact lens (DDCL) wear and investigate re-use of lenses according to country and DDCL material worn.

Methods: Optometrists invited eligible DDCL patients from their practices to participate in a survey on DDCL wear in Australia, Norway, the United Kingdom (UK) and the United States (US). Eligible participants completed an online or paper version of the survey.

Results: 805 participants completed the survey (96% online): Australia 13%, Norway 32%, UK 17%, US 38%. The median age was 38 years; 66% were female. Silicone hydrogel (SiHy) DDCLs were worn by 14%. Overall, 9% were non-compliant with DDCL replacement; Australia 18%, US 12%, UK 7% and Norway 4%. There were no differences with respect to sex, years of contact lens wear experience or DDCL material (SiHy versus hydrogels). The primary reason for re-use was "to save money" (60%). Re-use of DDCLs resulted in inferior comfort at insertion and prior to lens removal (p=0.001). 75% reported occasional napping and 28% reported sleeping overnight for at least one night in the preceding month, while wearing their DDCLs.

Conclusion: Non-compliance with replacement of DDCLs occurred in all countries investigated; the rate was highest in Australia and lowest in Norway. Re-use of DDCLs was associated with reduced comfort. DDCL wearers often reported wearing lenses overnight. It is important for optometrists to counsel their patients on the importance of appropriate lens wear and replacement for DDCLs.
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http://dx.doi.org/10.1016/j.clae.2013.05.004DOI Listing
December 2013

Exploring compliance: a mixed-methods study of contact lens wearer perspectives.

Optom Vis Sci 2013 Aug;90(8):898-908

Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.

Purpose: Using both quantitative and qualitative research methods, this article explores in detail the lens wear and care habits of adapted contact lens wearers and seeks a better understanding of what enables and constrains patient compliance with appropriate lens wear and lens care.

Methods: The study was conducted in two phases: a preliminary online questionnaire (quantitative phase), identifying types of noncompliance, and a series of sequentially conducted focus groups (qualitative phase), exploring constraints to, and enablers of, compliance.

Results: One hundred participants completed the online questionnaire; 12 of them also participated in one of four focus groups. The most frequently reported aspects of noncompliance revealed were failure to replace lenses when scheduled, inappropriate lens purchase and supply, sleeping while wearing lenses, use of tap water with lenses and failure to wash hands, failure to clean and replace cases regularly, and inappropriate use of care systems. Using an iterative process, a number of "themes" associated with noncompliance were identified in the focus group discussions. The most frequently occurring themes related to the consequences that may occur if patients were noncompliant with one or more aspects of their contact lens wear and the importance of receiving instructions regarding the most appropriate way to wear and care for their lenses. Most of the themes that emerged during the analysis were both constraints to, and enablers of, compliance.

Conclusions: This study confirms the frequent types of noncompliance with contact lens wear and care while offering a greater understanding of what may constrain and enables contact lens wear and care compliance. Future qualitative studies may help eye care practitioners and the contact lens industry to develop strategies and tools to aid compliance and success in contact lens wear.
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http://dx.doi.org/10.1097/OPX.0b013e3182956c46DOI Listing
August 2013

Ability of patients to recall habitual contact lens products and enhancement of recall using photographic aids.

Cont Lens Anterior Eye 2011 Oct 7;34(5):236-40. Epub 2011 Jul 7.

Centre for Contact Lens Research, University of Waterloo, Ontario, Canada.

Purpose: To determine the proportion of soft contact lens (CL) wearers who are able to recall their habitual products (lenses and care system) correctly from memory, and to evaluate the value of using photographic aids (PAs) to improve recall.

Methods: 103 soft lens wearers attended 2 visits to investigate their habitual CL product use. At the first visit they were asked to recall which products they were using and then to identify their products from PAs. They returned for a second visit with their products for confirmation.

Results: 51% correctly reported their lens brands from memory alone, which improved to 87% with the use of the PAs (p<0.001). 41% correctly reported their habitual care system from memory alone, which improved to 80% with the use of PAs (p<0.001). Females were better at recalling care system brand names than males (49% versus 27% correct, p=0.040) and wearers with more than 1 year experience with their habitual CLs had better recall than those with up to 1 year experience (63% versus 27%, p=0.014).

Conclusion: Less than 50% of contact lens wearers were able to recall the names of their habitual lens and lens care products correctly from memory. PAs improved this recall significantly for both contact lenses and contact lens care systems.
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http://dx.doi.org/10.1016/j.clae.2011.06.005DOI Listing
October 2011

The relationship between compliance with lens replacement and contact lens-related problems in silicone hydrogel wearers.

Cont Lens Anterior Eye 2011 Oct 13;34(5):216-22. Epub 2011 Apr 13.

Centre for Contact Lens Research, University of Waterloo, Ontario, Canada.

Purpose: To evaluate the relationship between compliance with replacement frequency (RF) and contact lens (CL)-related problems in silicone hydrogel (SiHy) wearers.

Methods: 501 SiHy wearers from seven optometry offices completed surveys regarding their lens wear and any CL related problems which they may have experienced in the preceding 12 months. File review was subsequently conducted at their optometry offices to confirm the information provided.

Results: 49% of respondents were wearing 2-week replacement (2WR) and 51% 1-month replacement (1MR) SiHy lenses. 67% wore their lenses for longer than the manufacturers' recommended RF (MRRF) and 60% for longer than their optometrist's recommended RF (ORRF). The mean RF was 2.6× the MRRF for 2WR and 1.5× for 1MR wearers (p<0.001) with median values of 31 and 37 days, respectively. Twenty-three percent reported signs or symptoms consistent with potential complications relating to CL wear. This rate was significantly higher for wearers who were non-compliant with the ORRF than compliant wearers (26% versus 18%, p=0.028). It was also higher for those multipurpose solution users who reported never/almost never rubbing and rinsing their lenses when compared with those who did this every night (29% versus 17%, p=0.007).

Conclusions: Two thirds of the SiHy wearers did not comply with the MRRF and 2WR wearers stretched the replacement interval of their lenses to a greater degree than 1MR wearers. Failing to replace lenses when recommended and failing to rub and rinse lenses were associated with a higher rate of patient-reported CL problems.
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http://dx.doi.org/10.1016/j.clae.2011.03.001DOI Listing
October 2011

Comfort and adaptation to silicone hydrogel lenses for daily wear.

Eye Contact Lens 2008 Jul;34(4):215-23

Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.

Objectives: To investigate initial comfort and adaptation of currently successful low oxygen transmissibility soft lens wearers refitted with silicone hydrogel (SH) lenses for daily wear.

Methods: Fifty-five subjects were enrolled in a subject-masked 5-month clinical trial in which they wore 5 SH lenses in a randomized, crossover design. Comfort, burning, and dryness were rated on scales of 0 to 100 immediately on insertion and the time for lens settling was recorded. Symptoms were then rated at various times, using BlackBerry wireless communication devices (Research in Motion, Waterloo, Canada), during the day for 2 cycles of 2 weeks wear for each lens type.

Results: Comfort immediately on insertion varied between lens types (P=0.002). All lens types were reported by the subjects to have settled within 30 to 45 sec of insertion (P=0.14) and "settled" comfort was greater than comfort immediately on insertion (P<0.001). Comfort within the first hour of wear also varied between lens types (P=0.02). Comfort during the day decreased significantly for all lenses (P=0.001), but there was no difference between lenses (P=0.19) and no effect of lens age (P=0.15). The wearing times were greater with the SH lenses than the habitual lenses worn before study commencement (P=0.001). Overall performance of the lenses after 4 weeks was high, with no difference between lenses (P=0.45).

Conclusions: Initial comfort and adaptation to all SH lenses were good and no differences in the overall ratings were found between the 5 SH lenses investigated. Decreased comfort was noted later in the day with all lens types, but longer wearing times were reported with the SH lenses than previous hydroxyethyl methacrylate-based lenses.
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http://dx.doi.org/10.1097/ICL.0b013e31816499dcDOI Listing
July 2008

Effect of lens base curve on subjective comfort and assessment of fit with silicone hydrogel continuous wear contact lenses.

Optom Vis Sci 2002 Oct;79(10):633-7

Centre for Contact Lens Research, University of Waterloo, Ontario, Canada.

Purpose: To study the effect of base curve on subjective comfort of silicone hydrogel extended wear lenses.

Methods: Ninety-five subjects were first trial fitted with 8.6-mm base curve lotrafilcon A (Focus Night & Day) lenses and then with 8.4-mm lenses only if poor subjective comfort or poor fit was present. Comfort and fit were assessed after 15 min. Subjects with discomfort or signs of poor fit were then trial fitted with 8.4-mm lenses.

Results: Of 190 eyes, 74.2% were fitted with 8.6-mm lenses, and 23.7% required 8.4-mm lenses. Two (2.1 %) subjects could not be fitted with either base curve. Mean steep keratometry (K) reading for eyes dispensed with 8.6-mm lenses was 43.88 D and 45.56 D for eyes dispensed in the 8.4-mm lenses (p < 0.001).

Conclusions: A clinically useful criterion showing the need for 8.4-mm lenses was steep K of > or = 45.50 D; 77% of these eyes required the steeper lens for good comfort and fit. Subjective discomfort with 8.6-mm lenses was also a useful signal for the need of a steeper lens; mean comfort scores for those subjects rose from 6.33 with 8.6-mm lenses to 9.44 with the 8.4-mm lenses for eyes requiring the steeper lens (p < 0.001).
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http://dx.doi.org/10.1097/00006324-200210000-00008DOI Listing
October 2002
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