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Peer-reviewed articles

2021

Wolffsohn,J. S., Dumbleton,K., Huntjens,B., Kandel,H., Koh,S., Kunnen,C. M. E., Nagra,M., Pult,H., Sulley,A. L., Vianya-Estopa,M., Walsh,K., Wong,S., Stapleton,F. CLEAR - Evidence-based contact lens practice Contact Lens Anterior Eye 2021;44(2):368-397 [ Show Abstract ]

Evidence-based contact lens -->practice involves finding, appraising and applying research findings as the basis for patient management decisions. These decisions should be informed by the strength of the research study designs that address the question, as well as by the experience of the practitioner and the preferences and environment of the patient. This reports reviews and summarises the published research evidence that is available to inform soft and rigid contact lens history and symptoms taking, anterior eye health examination (including the optimised use of ophthalmic dyes, grading scales, imaging techniques and lid eversion), considerations for contact lens selection (including the ocular surface measurements required to select the most appropriate lens parameter, lens modality and material selection), evaluation of lens fit, prescribing (teaching self-application and removal, adaptation, care regimen and cleaning instructions, as well as -->minimising risks of lens wear through encouraging compliance) and an aftercare routine.

2019

Wong,S., Srinivasan,S., Murphy,P. J., Jones,L. Comparison of meibomian gland dropout using two infrared imaging devices Cont Lens Anterior Eye 2019;42(3):311-317 [ Show Abstract ]

Purpose: To measure the degree of meibomian gland (MG) dropout in the lower eyelid determined by analysis of images obtained from the LipiView II (LVII) and the Keratograph 5M (K5M).

Methods: The inferior eyelid of each participant was imaged in a random order using both devices. All images were subjectively assessed by a single-masked investigator to determine the extent of MG loss using the Arita 4-point meiboscore grading scale. The images were also semi-objectively analyzed with ImageJ to calculate the percentage of MG dropout, by tracing around the non-glandular area and the total exposed area of the lower lid.

Results: Twenty participants (mean age 37 years, range 23–60, 60% female) completed the study. A significant difference in meiboscore (mean ± SD) was obtained between the LVII and the K5M (1.43 ± 0.78 vs. 1.90 ± 0.81, Z = 3.25, p = 0.001). The meiboscore 95% limit of agreement (LOA) ranged from −1.88 to +0.93. A significant difference was found with mean ImageJ percentage dropout between the LVII and the K5M (31.5% vs 43.4%, t = −4.8, p = 0.00003). The percentage dropout 95% LOA ranged from −42.79% to +19.06%.

Conclusions: LVII images had significantly lower meiboscores and less percentage MG dropout. Varying amounts of dropout were observed between the devices due the amount of eyelid that was typically everted and because of differences in image quality. These results indicate that these devices should not be used interchangeably to evaluate MG dropout.

2018

Wong,S., Murphy,P.J., Jones,L. Tear evaporation rates: What does the literature tell us? Contact Lens and Anterior Eye 2018;41(3):297-306 [ Show Abstract ]

Purpose: A previous literature review reported tear evaporation rates (TERs) from studies conducted on rabbits and humans between 1941 and 2003. Closer examination of the presented data revealed inaccuracies in the reporting of some values. This paper presents updated tables of TERs using values from the original papers cited in the review, in addition to incorporating new studies published between 2003 and 2016. Methods: A copy of each paper cited in the literature review was obtained and checked against the evaporation rate reported in the review. If the expected value could not be found in the cited paper, other papers by the same author were consulted to see if the value had been reported elsewhere. A PubMed and Scopus database search was conducted to find papers published on tear evaporimetry since 2003. Results: Two new tables of TERs were created, based on the values reported by the original author. To aid in interpretation, the majority of results are expressed in units of x 10−7 g/cm2/sec. Where it was not possible to convert these values, some values are expressed as x 10−7 g/sec, x 10−7 g/sec/eye or W/min. Conclusions: Two new tables of TERs have been compiled to provide an accurate representation of the values reported in the original papers. These tables can be used as a point of reference for other researchers to compare their results.

Scientific Presentations

2020

Wong S, Murphy P, Jones L. Impact of contemporary contact lens wear on tear evaporation measured using a novel evaporimeter The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Purpose : To determine whether a novel binocular evaporimeter is able to detect changes in tear evaporation rate (TER) before and while wearing delefilcon A and nesofilcon A contact lenses (CL).

Methods : The evaporimeter consists of a pair of swimming goggles modified with a temperature and relative humidity (RH) sensor embedded in both the right and left goggle lenses. For each measurement, the evaporimeter goggles were positioned and held tightly over the palpebral aperture of both eyes (to ensure an air-tight seal) for 20 seconds. There were two measurement conditions: Open Eye, during which the participants blinked every 3 seconds, and Closed Eye, when the eyes were closed. The difference between the Open and Closed Eye measurements was used to determine the TER from the ocular surface. TER was calculated as the slope of the change in RH in the period 5 to 13 seconds after the evaporimeter was placed over the eyes. Three repeated measurements were taken and averaged together. Two baseline TER measurements were recorded (15-minute interval) prior to CL insertion. Participants were randomized for delefilcon and nesofilcon CL lens wear in either eye. TER was measured after 15 minutes and ≥6 hours of CL wear. Measurements over time and between CL types were compared using repeated measures ANOVA with Bonferroni correction. (Mean±SD: Ambient temperature, 23.2±1.1°C; RH, 43.9±7.7%).

Results : Twenty habitual CL wearers (mean age: 28 years, range 18-71, 95% female) completed the study. Both evaporimeter sensors were able to detect a significant change in TER over time (right: p=0.003, left; p<0.0001). TER was significantly higher after 15 minutes (right: p=0.035, left: p<0.0001) and 6 hours of CL wear (right: p=0.002, left: p=0.001), compared to second baseline measurement. Both CLs showed a significant increase in TER between 15 minutes and 6 hours of lens wear (p=0.001). No significant difference in TER was observed between delefilcon and nesofilcon (p=0.770).

Conclusions : The novel evaporimeter was able to simultaneously measure TER from both eyes. TER significantly increased when CLs were worn and was highest after ≥6 hours of CL wear. No significant differences in TER were found between delefilcon A and nesofilcon A, which suggests that contemporary daily disposable CL materials behave in a similar manner with regards to their impact on TER, regardless of water content or material.

This is a 2020 ARVO Annual Meeting abstract.

2019

Wong S, Bhamra T, Jones L, Tighe B. Subjective assessment of contact lens handling: what can we learn from the past? BCLA Conference, Manchester, UK, 2019 [ Show Abstract ]

Purpose: This study examines correlations between clinician-assessed subjective ease of handling of soft contact lenses, and laboratory-assessed physicochemical characteristics. High CL dropout rates caused by handling problems and difficulties in objectively measuring handling performance underline the clinical importance of such studies. The first stage involved assessment of conventional hydrogel lenses widely available in the 1980s, some currently available and some not. This is a platform for assessment of SiHy lenses in which effects of inherently lower coefficients of friction need to be assessed in parallel.

Methods: The prospective, single-masked study involved participants (no previous long-term CL wear history) each asked to rate the ease of handling of 23 different types of soft CLs on a 10-point continuous scale. Primary physicochemical data (e.g. EWC, lens thickness and mass, tensile modulus) were collected and additionally transposed into derived quantities (e.g. stiffness factor, plasticising factor).

Results: The data for the conventional hydrogels revealed:
• The early conventional hydrogels Hydrocurve II and SofLens 38 had lowest mean ± SD handling scores of 6.08 ± 1.56 and 6.08 ± 1.98, respectively.
• Excelens had the highest mean handling score of 8.67 ± 1.78.
• No significant correlation was found between handling and the equilibrium water content (Spearman’s r = -0.34, p = 0.11) or centre thickness (Spearman’s r = 0.33, p = 0.13)
• Handling of hydrogel CLs was strongly correlated with the stated modulus (Spearman’s r = 0.70, p = 0.02), the equilibrium water content (Spearman’s r = 0.64, p = 0.04) and centre thickness (Spearman’s r = 0.76, p = 0.01).

Conclusions: The poster will discuss detailed lens data including graphical presentation of “derived” factors combining thickness and modulus together
with the observations that SiHy CLs had higher mean handling scores than hydrogel CLs. All current CLs had mean handling scores of > 6.0.

2017

Wong S, Lum E, Planaguma Cornella A, Murphy P, Jones L. Surface temperature change in soft contact lenses: an in vitro study Invest Ophthalmol Vis Sci 2017;E-Abstract 3097

Wong S, Srinivasan S, Jones L. Comparison of meibomian gland dropout using two infrared imaging devices Optom Vis Sci 2017;94: E-Abstract 174064

Professional Publications

2021

Wong S. CLEAR report summary: Evidence-Based Contact Lens Practice https://contactlensupdate.com/2021/06/15/evidence-based-contact-lens-practice/ 2021

2017

Wong S. A review of contact angle techniques ContactLensUpdate.com 2017