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Peer-reviewed articles


Moezzi,A. M., Varikooty,J., Luensmann,D., Schulze,M., Ng,A. Y., Karkkainen,T., Xu,J., Jones,L. The short-term physiological impact of switching reusable silicone hydrogel wearers into a hydrogel daily disposable multifocal Clinical Ophthalmology 2019;13:1193-1202 [ Show Abstract ]

Purpose: To evaluate ocular physiological responses to etafilcon A multifocal (etMF) daily disposable (DD) lenses after 4 weeks of wear, when switching from habitual silicone hydrogel (SiHy) daily wear.
Method: A single-arm, open-label, bilateral dispensing study was conducted in 39 habitual spherical SiHy wearers (14 hyperopes; 25 myopes). Clinical visits occurred with habitual SiHy (control) at baseline and after 4 weeks of etMF DD open-eye lens wear at exit. Objective limbal/bulbar hyperemia using the Oculus K5M (0–4) and subjective grading of lid wiper epitheliopathy (LWE) (0–4) were tested for non-inferiority (NI), using a margin of 1 grade. Corneal thickness along a 10 mm cord was measured using the Visante OCT and tested for NI using a 30 μm margin. Corneal staining area was graded (0–100%).
Results: The least-square mean differences (LSMD) and 95% confidence interval (95% CI) between etMF DD and habitual SiHy in central and peripheral corneal thickness (μm) were 3.64 (−2.0, 9.29) and 3.0 (−7.72, 13.72) in hyperopic, and 3.56 (−0.66, 7.78) and 6.40 (−1.62, 14.42) in myopic subjects. The LSMD (95% CI) for bulbar and limbal hyperemia were −0.08 (−0.19, 0.02) and −0.01 (−0.12, 0.09) in hyperopes, and 0.04 (−0.03, 0.12) and 0.04 (−0.04, 0.11) in myopes. The LSMD (95% CI) for LWE were 0.11 (−0.39, 0.60) and 0.30 (−0.07, 0.67) for hyperopes and myopes, respectively.
Conclusions: No clinically significant differences in a variety of physiological responses were found when habitual reusable SiHy daily wear subjects were refitted into hydrogel etMF, when the subjects were followed for 4 weeks.


Ng,A. Y., Keech,A., Jones,L. Tear osmolarity changes after use of hydroxypropyl-guar-based lubricating eye drops Clinical Ophthalmology 2018;12:695-700 [ Show Abstract ]

Purpose: To evaluate tear osmolarity after using a hydroxypropyl-guar (HP-guar)-based lubricating eye drop four times daily (QID) for 3 weeks. Methods: Thirty-one participants with dry eye disease (Ocular Surface Disease Index [OSDI] score ≥20 and tear osmolarity ≥300 mOsm/L in at least one eye) were enrolled in this prospective, dispensing, non-randomized study involving a baseline visit and 3‑week follow-up. Tear osmolarity, non-invasive tear break up time (NITBUT), conjunctival hyperemia, corneal and conjunctival staining were determined at baseline. Participants were instructed to instill one drop of a HP-guar-based drop QID in each eye for 3 weeks. At the follow-up visit, the symptoms and ocular surface parameters were reassessed. At this visit, one HP-guar drop was instilled into each eye and osmolarity was measured after 15 minutes, to examine short-term changes in osmolarity. Results: Twenty-eight participants completed the study (5M, 23F; median age 54 yrs, range 25-83 yrs). At baseline, mean OSDI score was 44.9±15.2 and mean osmolarities were 314.63±11.9/306.6±10.1 mOsm/L (worst eye [WE]/better eye [BE]). After 3 weeks, mean osmolarity reduced to 307.7±15.7/303.9±11.3 mOsm/L (WE/BE; p<0.05 and p=0.228, respectively) and mean OSDI scores reduced to 28.3±17.0 (p<0.01). A significant reduction in osmolarity was observed 15 minutes after instilling the lubricating drop (p<0.05 WE, p=0.09 BE). Significant improvements in central corneal staining (p<0.05 OU) and NITBUT (p<0.05 WE only) were observed. Reductions in conjunctival staining and hyperemia were observed, but were not significant (p>0.05). Conclusions: A significant reduction in tear osmolarity and improvements in dry eye symptoms, corneal staining, and NITBUT were observed after 3 weeks of QID use of a HP-guar-based lubricant drop. A decrease in osmolarity was also demonstrated 15 minutes after drop instillation.

Omali,N.B., Subbaraman,L.N., Heynen,M., Ng,A. Y., Coles-Brennan,C., Fadli,Z., Jones,L. Surface versus bulk activity of lysozyme deposited on hydrogel contact lens materials in vitro Contact Lens and Anterior Eye 2018;41(4):329-334 [ Show Abstract ]

Purpose: To determine and compare the levels of surface versus bulk active lysozyme deposited on several commercially available hydrogel contact lens materials. Methods: Hydrogel contact lens materials [polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon and etafilcon A with polyvinylpyrrolidone (PVP)] were incubated in an artificial tear solution for 16 h. Total activity was determined using a standard turbidity assay. The surface activity of the deposited lysozyme was determined using a modified turbidity assay. The amount of active lysozyme present within the bulk of the lens material was calculated by determining the difference between the total and surface active lysozyme. Results: The etafilcon A materials showed the highest amount of total lysozyme activity (519 ± 8 μg/lens, average of Moist and Define), followed by the ocufilcon material (200 ± 5 μg/lens) and these two were significantly different from each other (p < 0.05). The amount of surface active lysozyme on etafilcon and ocufilcon lens materials was significantly higher than that found on all other lenses (p < 0.05). There was no active lysozyme quantified in the bulk of the nelfilcon material, as all of the active lysozyme was found on the surface (1.7 ± 0.3 μg/lens). In contrast, no active lysozyme was quantified on the surface of polymacon, with all of the active lysozyme found in the bulk of the lens material (0.6 ± 0.6 μg/lens). Conclusions: The surface and bulk activity of lysozyme deposited on contact lenses is material dependent. Lysozyme deposited on ionic, high water content lens materials such as etafilcon A show significantly higher surface and bulk activity than many other hydrogel lens materials.

Scientific Presentations


Woods J, Ng AY, Luensmann D, Guthrie S, Jones L. Short-term comfort comparison of two daily disposable contact lenses of different material and modulus Invest Ophthalmol Vis Sci 2018;E-Abstract 1753 [ Show Abstract ][ PDF ]

Purpose: Daily disposable contact lenses (DDs) are now widely available in both silicone hydrogel (SH) and hydrogel (H) materials. The higher oxygen transmissibility of SH materials provides many benefits, but their higher modulus has been linked with reduced lens comfort compared to H lenses. This randomized, double-masked clinical trial assessed the short-term comfort of two DDs of differing modulus, yet similar water content (WC): a SH-DD (somofilcon A; clariti® 1 day; CooperVision; 0.50MPa modulus, 56% WC) and a H-DD (etafilcon A; 1-Day Acuvue® Moist®; Johnson & Johnson; 0.29MPa modulus, 57% WC).

Methods: 120 subjects wore the lenses contralaterally, over one day. Targeted recruitment meant that 60 subjects were habitual H-DD wearers (all adapted wearers of 1-Day Acuvue Moist), 60 were non-DD habitual wearers (adapted to various SH and H re-usable lenses). Subjects rated lens comfort on a 0-100 integer scale (100= cannot be felt) at insertion and then hourly until 8hrs. Of particular interest was the comfort at the beginning and end of the 8hr wear period and these data points were tested for equivalence. At the final visit subjects were asked for their lens preference, based on comfort.

Results: Mean subjective comfort was not different between SH-DD and H-DD across the wear period (p>0.05), on insertion (87±14 SH-DD vs 89±14 H-DD; p>0.05) or after 8hrs (82±18 SH-DD vs 83±17 H-DD; p>0.05). Based on equivalency margins of ±5-points, the study lenses showed equivalent comfort at insertion (p=0.03) and at 8hrs (p=0.001). Both lenses exhibited a significant reduction in comfort over the 8hr period (both p<0.001). When subjects’ data was divided according to their habitual lens modality groups (60 H-DD wearers and 60 re-useable wearers), there were also no comfort differences between the study lenses, either across time, or at insertion and 8hrs (all p>0.05). Lens preference was not different between lenses at dispensing or at the final visit (both p>0.05).

Conclusions: Initial and 8hr comfort were not compromised with the SH-DD compared to the H-DD, despite its higher modulus, and there was no difference in the lens preference distribution. The results suggest that lower comfort should not be anticipated when fitting SH-DDs of an appropriate design, thus allowing other material properties such as high oxygen permeability to be considered.

Woods J, Ng AY, Luensmann D, Jones L. Short-term comfort comparison of a low modulus hydrogel vs a higher modulus silicone hydrogel daily disposable lens Contact Lens & Anterior Eye 2018;41, Supp 1:S42


Moezzi A, Varikooty J, Luensmann D, Schulze M, Ng AY, Karkkainen T, Xu J, Jones L. Evaluation of Clinical Success with etafilcon A multifocal daily disposable lenses Optom Vis Sci 2017;94: E-Abstract 175341


Ng AY, Keech A, Jones L. Detection of Tear Film Osmolarity Changes After Use of a Hydroxypropyl Guar-Based Lubricating Eye Drop Invest Ophthalmol Vis Sci 2015;56: E-abstract 4429 [ PDF ]

Schulze M, Luensmann D, Ng AY, Panjwani F, Srinivasan S, Jones L. The relationship between the positioning of multifocal contact lens optics and satisfaction with vision Optom Vis Sci 2015;92: E-abstract 155256 [ PDF ]

Professional Publications


Ng AY. Summary: Diagnostic methodology report ContactLensUpdate.com 2017


Ng AY. Makeup and your eyes: friend or foe? ContactLensUpdate.com 2014

Ng AY. Summary: Report of the Definition and Classification Subcommittee ContactLensUpdate.com 2014

Ng AY, Bitton E, Jones L. Demodex infestation of the eyelashes Contact Lens Spectrum 2014;29, 12: 36-41



Jones L, Srinivasan S, Ng AY, Schulze M. Clinical Diagnostic Instruments In: Contact Lens Practice; 3rd Ed. Elsevier, Oxford, UK. 2017.