Scientific Presentations


Guthrie S, Luensmann D, Woods J, Vega J, Orsborn G. Acceptability of different lens materials in habitual wearers of frequent replacement lenses American Academy of Optometry, San Diego, 2022 [ Show Abstract ]

Purpose: New soft lens materials frequently enter the market for different lens wear modalities and the question remains as to how these compare to established products. The purpose of this study was to compare the subjective performance of two silicone hydrogel (SiHy) lenses that employ different technologies to improve wearer comfort: the recently introduced lehfilcon A (leh-A)(Alcon) lens employs ‘Water Gradient Technology’ and the established comfilcon A (com-A)(CooperVision) lens employs ‘Aquaform Technology’.

Methods: This study was a prospective, bilateral, double-masked, randomized, cross-over, daily-wear design involving two different monthly replacement SiHy lens types (leh-A and com-A). Young adults who habitually wore frequent replacement spherical lenses were recruited at four clinical sites in the US. Each of the two lens types was worn for one month and participants used their habitual care products. Throughout each month, participants recorded their lens wear comfort on several days at home and during study visits (0-10 scale, 10=can’t feel the lenses) and answered agreement (5-point strongly/slightly agree, neither agree or disagree, strongly/slightly disagree) and preference (5-point strong/slight prefer first/second lens pair, no preference) questions. Statistical differences were determined by Wilcoxon matched pairs and binomial testing.

Results: Sixty-three participants (44F:19M), mean age 27.5 ± 4.8 years [18 to 35 years] were included in the analysis. The mean spherical refraction was -3.12 ± 1.6D [-6.50D to +1.25D]. Overall comfort ratings on Days 1, 14, 27 were 8.5, 8.0, 7.7 for com-A and 8.8, 8.2, 8.1 for leh-A. For both lens types, comfort ratings were higher at the beginning of the month (p<0.01), with no statistically significant difference between lenses for any time point (all p>0.05). The mean drop in overall comfort after one month of wear was the same for both lens types (com-A: 0.7, leh-A: 0.7, p>0.05). At 1-month, participants rated overall satisfaction with comfort similarly (com-A: 8.0, leh-A: 7.8, p>0.05) and there was no difference in the number of participants preferring each lens when considering comfort on application (26:24), removal (27:24) and overall (29:27)(com-A:leh-A, all p>0.05). For each lens type, a similar number of participants agreed compared to disagreed with the statement “These lenses feel like nothing even after one month of wear” (each lens type p>0.05) and no statistically significant differences were found between the lens types (p>0.05).

Conclusion: Despite significant differences in material composition and surface technologies between com-A and leh-A, the subjective contact lens comfort experience over 1 month was similar. The preference ratings further highlight the importance of providing patients with different options and deciding together which lens type is best for them to help ensure long-term success with lens wear.

Jones L, Bose S, Phan CP, Rizwan M, Tse JW, Yim EKF. Fabrication of an enzyme-triggered therapeutic releasing biomaterial for bandage contact lenses American Academy of Optometry, San Diego, 2022 [ Show Abstract ]

Purpose: The use of a soft bandage contact lens in combination with a therapeutic could help improve the treatment of corneal injuries. The purpose of this study was to develop an enzyme-triggered therapeutic release platform using a unique gelatin methacrylate formulation (GelMA+) and bovine-lactoferrin (BLF), a model therapeutic.

Methods: Two formulations of GelMA+, 20% and 30% w/v, were prepared using UV polymerization. The properties of the material, including porosity, tensile strain, and swelling were characterized. The degradation of GelMA+ in the presence of matrix metalloproteinase-9 (MMP-9), typically found upregulated at a wounded sight, from 0 – 300 µg/mL of the enzyme was also evaluated. Cell viability, cell growth, and cytotoxicity on the GelMA+ gels were determined using the AlamarBlueTM assay and the LIVE/DEAD™ Viability/Cytotoxicity Kit staining with immortalized human corneal epithelial cells after 5 days. For a preliminary drug release study, the 30% GelMA+ gels were also loaded with 3 µg of BLF, and the release of the therapeutic was evaluated over 5 days at various MMP-9 concentrations (0, 100, 300 µg/mL) in phosphate-buffered saline (PBS 1X) at 37 °C. The gels were washed for 1 hour at room temperature (22 – 24 °C) before the release phase to remove any loosely bound BLF on the surface. The amount of BLF released was measured using an ELISA kit and UV absorbance at 450 nm, n=4.

Results: The 30% w/v GelMA+ had a higher crosslinking density, tensile strength, smaller pore size, and lower swelling ratio than the 20% w/v GelMA+ (p<0.05). The degradation rate of the 20% w/v gel was much faster (p<0.001), degrading almost completely after 48 hours at 300 µg/mL of MMP9. After 5 days, There was no cytotoxicity detected in the live/dead staining for either concentration, but the 30% w/v GelMA+ showed significantly higher cell viability (p<0.05). In the drug release study, there was no burst release of BLF observed for the 30% w/v gel, and the release of the therapeutic was sustained over 5 days. The rate of release from the gel significantly increased with increasing concentrations of MMP-9 (p<0.001), correlated to the rate of degradation of the gels.

Conclusion: The results showed that degradation of GelMA+ can be tuned by modifying the cross-linking density or exposure to different concentrations of MMP-9. The release of BLF from 30% GelMA+ is driven by a combination of diffusion and degradation of the material by MMP-9 enzymes. Future work will focus on optimizing the materials to deliver other therapeutic agents at physiologically-relevant concentrations of MMP enzymes

Luensmann D, Guthrie S, Woods J, Vega J, Orsborn G. Performance evaluation of two toric multifocal contact lenses available in different parameter increments Nederlands Contactlens Congres, Veldhoven, Netherlands, Jun 27, 2022 [ Show Abstract ]

Toric multifocal contact lenses (TMFCLs) offer vision correction to the astigmatic presbyopic population. The vision outcome was determined in existing soft lens wearers when fit with two TMFCLs, available in different parameter steps; 5 vs 10 degree axis increments and 6 vs 2 near adds.

In a multisite, prospective, randomised, participant-masked, 1-month crossover, bilateral dispensing study, habitual soft lens wearers ≥42years old with minimum 0.75DC astigmatism were fit with two monthly replacement, silicone hydrogel TMFCLs (comfilcon A (com-A); CooperVision, samfilcon A (sam-A); Bausch & Lomb). The manufacturer’s fitting guides were followed, and lens prescriptions were optimised after 3-7 days of wear, before the 1-month wear period. Vision outcomes included visual acuity (LogMAR), 3-point ratings (met/exceeded or did not meet my needs), and 5-point preference ratings (strongly/slightly prefer lens 1 or 2, no preference).

Fifty-six participants age 53.6±8.6 years were included in the analysis (OD mean(±SD): sph -2.47D(±2.38), cyl -1.27D(±0.47), add 1.88D(±0.48)). For com-A axes ending in 5 degrees were chosen for 47% of eyes and each add power was prescribed. After one month, LogMAR acuity was similar for both lens types for distance, intermediate and near (p>0.05 for all). On days 7, 14 and 28 participants rated that com-A met their needs better for ‘Overall speed and ability to change focus between distances’, ‘Vision stability throughout the day’ and ‘Overall vision clarity’ (p<0.05 for all); other ratings showed no difference between lenses. A preference was found for com-A for vision clarity for ‘intermediate tasks’ (p=0.03), ‘near tasks’ (p=0.01), ‘during digital device use' (p<0.01) and for ‘overall vision clarity’ (p=0.01). No preference was indicated for distance tasks (p>0.05).

The higher accuracy of prescribing for com-A due to the 5-degree axis steps and the 6 near adds may have contributed to the better vision outcomes reported with com-A.

Nagaarudkumaran N, Mirzapur P, McCanna DJ, Jones L, Ngo W. The effect of Lifitegrast on cytokine response from immortalized human corneal epithelial cells under hyperosmolar stress American Academy of Optometry, San Diego, 2022 [ Show Abstract ]

Purpose: Lifitegrast is a topical ophthalmic pharmaceutical used to treat moderate to severe dry eye disease. Its mechanism of action occurs by inhibiting the binding between lymphocyte function-associated antigen 1 (LFA-1) and intercellular adhesion molecule 1 (ICAM-1). As an integrin antagonist, lifitegrast binds to LFA-1, preventing the formation of the LFA-1/ICAM-1 complex.
Given that lifitegrast is a small molecule with potential to act on other intracellular targets, this study aimed to examine its effect on the inflammatory response of immortalized human corneal epithelial cells (HCECs) undergoing hyperosmolar stress.

Methods: HCECs were exposed to hyperosmolar media (500 mmol/kg via sodium chloride) and treated with 1% or 3% lifitegrast. A treatment without lifitegrast was used as a control. Following an exposure period of 0.25-hours, 3-hours, 6-hours and 12-hours, the conditioned cell media was collected and cytokines IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, TNF-α and IL-17A were quantified using electrochemiluminescent multiplexing assays.

Results: Cells exposed to 1% lifitegrast exhibited significantly lower IL-1β, IL-6, IL-8, and TNF-α compared to the control (all p < 0.0172) at 6-hours and lower IL-6, IL-8, and TNF-α (all p < 0.0053) at 12-hours. With the 3% lifitegrast exposure, there was a significant reduction in IL-1β, IL-6, IL-8, and TNF-α (all p < 0.0224) at 6 and 12-hours. By the 12-hour mark, IL-10, IL-17A, IFN-γ, and IL-2 were significantly higher in both 1% and 3% lifitegrast compared to the control (all p < 0.0254). IL-12p70 was significantly higher with 3% lifitegrast only at all time points (all p < 0.0146), and IL-4 was significantly higher with 3% lifitegrast only at 0.25 and 3-hours (both p < 0.0249) compared to the control. There was no significant difference in IL-13 concentration between 1% and 3% lifitegrast at any time point.

Conclusion: Lifitegrast reduced IL-1β, IL-6, IL-8, and TNF-α from HCEC exposed to hyperosmotic stress. However, lifitegrast also increased IL-10, IL-12p70, IL-17A, IL-2, IL-4, and IFN-γ. Therefore, in addition to LFA-1/ICAM-1 antagonism, it is possible that lifitegrast may function additionally to inhibit the innate immune response and promote suppressive immune function.

Ng AY, Dantam J, Woods J, McEwen B, Jones L.. Examining Symptomatic Relief and Kinetic Tear Film Stability of I-DROP MGD Eye Drops Optometry's Meeting ePosters Virtual Event, Jun 8, 2022 [ Show Abstract ]

I-DROP MGD is a novel formulation of viscoadaptive hyaluronan, phosphorylcholine and glycerin to support integration, stabilization and enhancement of the tear film lipid layer as well as hydration of the ocular surface. The purpose of this study was to compare the difference in tear film measures after instilling I-DROP MGD (test) compared with another hyaluronic acid-based lubricant, Thealoz Duo (control), and to examine the subjective relief of dry eye symptoms with I-DROP MGD over 1-week.

This prospective pilot study (n=10) comprised of two parts. Part 1 was a non-dispensing, doublemasked study involving contralateral application of test and control drops, followed by a two-hour observation period. Non-invasive tear break-up time (NITBUT), tear meniscus height (TMH) and lipid layer thickness (LLT) were measured out to 2 hours. Part 2 was a dispensing study, where one bottle of I-DROP MGD was provided to participants to use bilaterally at least once daily for 7 days. After 7 days, subjective ratings (0-100 scale) of comfort, soothing and quality of vision along with OSDI and SPEED scores were collected and compared with participant's habitual eye drops.

Part 1: NITBUT and TMH were significantly greater with I-DROP MGD (14.2 ± 5.1s and 0.42 ± 0.22mm) compared to Thealoz Duo (10.5 ± 5.7s and 0.29 ± 0.10mm) after 60 minutes (p =0.037) and 5-minutes of instillation (p =0.022) respectively; LLT was significantly thicker with Thealoz Duo (79.5 ± 15.7nm) compared to I-DROP MGD (68.5 ± 13.8nm) after 5 minutes of instillation (p=0.005). Part 2: Subjective ratings for comfort and soothing were significantly greater with I-DROP MGD (81.6 ± 5.7 and 86.8 ± 8.1) compared to habitual eye drops (73.3 ± 13.7 and 75.3 ± 19.8), p=0.027 and p=0.010 respectively. No significant differences were observed for quality of vision. OSDI and SPEED scores were significantly lower following use of I-DROP MGD (33.2 ± 11.7 and 11.1 ± 3.6) when compared to habitual drops (45.2 ± 14.7 and 14.9 ± 2.7), p=0.017 and p=0.006 respectively.

When used for 7 days, I-DROP MGD resulted in clinically relevant reductions in dry eye symptoms, measured with OSDI.

Ng AY, Woods J, Jones L. The impact of fluid intake on dry eye symptoms and signs American Academy of Optometry, San Diego, 2022 [ Show Abstract ][ PDF ]

Purpose: Preventing dehydration is essential for optimal bodily function. This study investigated if maintaining the recommended daily fluid intake set out by the Dietitians of Canada affects tear film measures and ocular symptoms in participants with and without dry eye disease (DED).

Methods: This was a prospective, non-randomized interventional pilot study. Twenty participants were enrolled: 10 with DED and 10 healthy controls. At Baseline, symptom questionnaires (Ocular Surface Disease Index [OSDI] and Ocular Comfort Index [OCI]) and habitual fluid intake was documented. Baseline tear film measures (non-invasive tear break-up time [NITBUT], tear meniscus height [TMH], non-anaesthetized Schirmer test) were also assessed. Eligible participants were instructed to attain the recommended daily intake (3.0L for males, 2.2L for females) for 7 days, while keeping a diary to track all fluids consumed during this time. On Day 8, participants returned for follow-up: symptom questionnaires and tear film measures were reassessed and fluid intake diaries were collected.

Results: Twenty participants completed the study; 4/20 (3 DED, 1 control) met the fluid intake recommendation prior to starting the study and were excluded from data analysis. All remaining 16 participants (8 male, 8 females; 7 DED, 9 control) increased their fluid intake for 7 days. There was a statistically significant and clinically relevant improvement in OSDI scores in the DED group after the fluid intake intervention only (Control baseline: 4 ± 3, Day 8: 2 ± 3, p>0.05; DED baseline: 40 ± 12, Day 8: 29 ± 8, p<0.001). Similarly, OCI scores (0-100, where 100=worst level of discomfort) were 5-points better in both groups after maintaining the fluid intake (Control baseline: 26 ± 5, Day 8: 21 ± 9; DED baseline: 40 ± 3, Day 8: 35 ± 4; both p<0.05). On Day 8, TMH values were 0.1mm greater in the DED group compared to baseline however Schirmer test values did not reflect a similar change. In the control group, TMH and Schirmer test values on Day 8 were similar to baseline (TMH Control baseline: 0.32 ± 0.11, Day 8: 0.30 ± 0.12, p>0.05; DED baseline: 0.21 ± 0.09, Day 8: 0.31 ± 0.15, p=0.043. Schirmer Control baseline: 26 ± 12, Day 8: 27 ± 10; DED baseline: 24 ± 14, Day 8: 23 ± 15; both p>0.05). Compared to baseline, a small increase in NITBUT was observed in the control group and a small decrease observed in the DED group, however neither changes were statistically significant (Control baseline: 11.7 ± 6.5, Day 8: 12.9 ± 8.3; DED baseline: 8.1 ± 4.2, Day 8: 6.4 ± 3.1; both p>0.05).

Conclusions: In participants with DED, maintaining increased fluid intake for 7 days significantly improved OSDI and OCI scores and increased tear volume however, there was no change in non-anaesthetized Schirmer tests or NITBUT. In the control group, small changes in tear film measures were found, however these were not clinically or statistically significant.

Phan C-M, Wulff D, Garg P, Jones L.. Developing a novel in vitro eye model using 3D bioprinting for drug delivery studies The Association for Research in Vision and Ophthalmology, Denver, CO, USA, May 1, 2022 [ Show Abstract ]

Purpose: To develop an in vitro eye model using a novel 3D bioprinting method for testing the release of ophthalmic formulations to the posterior ocular region.

Methods: The eye model was designed using CAD software and includes both an anterior aqueous chamber and a posterior vitreous chamber. The vitreous chamber is surrounded by a blood chamber to mimic vessels that can be used to transport a blood-like substance. Three inlet ports control the flow of fluid into the chambers and the blood channels, and the three outlet ports allow fluids to exit these compartments. The eye model was 3D printed on a commercial mSLA printer (Photon Mono X, AnyCubic), which was retrofitted with a humidity and temperature control module to create a printing environment at 37°C and >80% humidity. The bioink formulation consisted of 10% gelatin methacrylate (GelMa). After printing, the models were incubated at 37°C to remove any uncured GelMa within any hollow compartments. For this study, phosphate-buffered saline was used as an aqueous and vitreous humour mimic. To evaluate the diffusion of a small hydrophilic molecule on the eye model, a contact lens (Air Optix) was soaked with a water-soluble red food dye for 1 hour and then placed on the eye model. The amount of dye in the anterior chamber, posterior chamber, and blood channels was measured using UV spectrophotometry after 24 hours.

Results: The entire model can be printed without any support structures within approximately 3 hours. The 3D printed eye model can also be autoclaved for testing that requires sterility. Because there were no diffusion barriers present in the current model, the red dye was detected in all three chambers after 24 hours. The highest concentration of dye was found in the anterior chamber, followed by the blood chamber and then the posterior chamber.

Conclusions: The prototype developed in this study can be used as a starting point to develop enhanced 3D printed eye models to test drug release kinetics of various devices and formulations. Future work will focus on adding the appropriate diffusion barriers to better simulate drug diffusion through ocular tissues.

Layman Abstract: The aim of the study was to create an advanced eye model using commercial 3D printing methods. Current 3D bioprinters are extremely expensive and regular commercial 3D printers do not have the capabilities to print biological materials. We are developing a method to 3D print sophisticated eye models using inexpensive 3D printers. The models from this research can further be refined for studying drug absorption in the eye. This research will also enable researchers to create their own biological models using 3D printing methods.

Phan C-M, Wulff D, Jones L.. Developing bioinks for commercial mSLA printers and a method for quantifying print quality Canadian Biomaterial Society Conference, Banff, AB, May 25, 2022 [ PDF ]

Phan CM, Chan V, Drolle E, Shi C, Subbaraman L, Wu J, Jones L. Evaluating the in vitro wettability of contemporary reusable soft contact lenses using an in vitro blink model American Academy of Optometry, San Diego, 2022 [ Show Abstract ][ PDF ]

Purpose: To evaluate the in vitro wettability of four contemporary reusable soft contact lens materials (serafilcon A, senofilcon A, senofilcon C, lotrafilcon B, comfilcon A) over a 14-day simulated wearing period using a novel, physiologically relevant in vitro eye model.

Methods: The 14-day wearing period was simulated using an in vitro blink model (OcuBlink). A tear mimic solution containing relevant proteins and lipids was delivered to the eye model at a rate of 1.25 -2.25 µL/min. A tear film was created over the lens via an artificial eyelid that slid across an eyeball surface at 6 blinks/minute, with a lens in-situ, at room temperature and humidity above 50%. For each cycling day, the lenses were incubated on the eye model for 16 hours, followed by a 10 second rub-rinse each side with OPTI-FREE PureMoist Solution, and then incubated overnight for 8 hours in the same solution. Lens wettability was quantified at t = 0 (straight from blister pack), 1, 7, and 14 days via two methods, (1) sessile drop contact angle (CA) and (2) non-invasive keratographic tear-break-up time (NIKBUT), n = 4 for each lens type. Contact angles were measured using the Optical Contact Analyzer (DataPhysics, Germany). NIKBUT measurements were assessed on the OcuBlink via the OCULUS Keratograph 5M (OCULUS, Germany).

Results: At t = 0, comfilcon A (24.0 ± 5.3°) had the lowest contact angle, followed by lotrafilcon B (29.6 ± 6.5°), serafilcon A (67.7 ± 16.0°), senofilcon C (89.2 ± 6.0°), and senofilcon A (92.0 ± 3.1°). All contact lens materials had similar CA out of the blister pack compared to 7 days (p >0.05). There was a slight increase in CA between 7-14 days for serafilcon A and lotrafilcon B, but this was not statistically significant (p>0.05). The NIKBUT for all contact lens materials ranged between 4 – 9 seconds, and there were no significant differences between NIKBUT within the same lens type at any time point (p>0.05). NIKBUT at t = 0 was highest for serafilcon A (8.3 ± 1.7 s) (p<0.05), followed by lotrafilcon B (6.3 ± 1.4 s), comfilcon A (6.1 ± 1.5 s), senofilcon A (5.6 ± 1.1 s), and senofilcon C (5.5 ± 0.8 s).

Conclusion: Lenses with a very low CA did not translate into significantly higher NIKBUT. For some lens materials, notably serafilcon A, there was an increase in CA after 7 days of in vitro testing, which warrants further investigation.

Phan CM, Kapadia W, Qin Nm Zhao P, Ren C, Haines L, Jones L. Development of a microfluidic viscometer for measuring microliter-volume fluid samples American Academy of Optometry, San Diego, 2022 [ Show Abstract ][ PDF ]

Purpose: To develop a microfluidic viscometer capable of measuring the viscosity of microliter-volume fluid samples such as human tear fluid.

Methods: The microfluidic chip was designed using CAD software and laser cut from acrylic sheets into the desired shape and sizes. The various parts of the microfluidic chips were assembled and combined together using medical-grade double-sided tape. The micro-channels were coated with a repellant coating to provide a smooth and hydrophobic surface, which provided a straight flow path for a sample to approach flow equilibrium as it moves through the chip. The chip was attached to a syringe pump to control the flow rate. Additional supporting devices, including a high-speed camera and a pressure transducer, were used for analysis. Based on the difference in capillary pressure at the air-liquid interface, channel dimension, sample length, sample velocity, volumetric flow rate and contact angle, the viscosity of the fluid sample can be derived. For a preliminary experiment, the viscosity of an eye drop (Hydrasense, Bayer Inc., Canada) was measured by the developed microfluidic viscometer as well as a commercial cone/plate rheometer (Model: LVDV-III+, Brookfield Engineering Laboratories Inc, MA, USA) at a shear rate between 27.8 – 308 s-1, n=3.

Results: The minimum sample volume that was needed for measurement was 12 microliters, but this volume can be reduced with further optimization. The results showed that the viscosity values obtained for both the commercial rheometer and the microfluidic viscometer were in strong agreement. At a low shear rate (141 s-1), the viscosity of the eye drop was at 8.03 mPa·s, and at higher shear rates (622 s-1), the viscosity decreased to 6.33 mPa·s. The viscosity of the eye drop decreased with increasing shear rate, which reflects its shear-thinning properties. The maximum shear that was tested was 622 s-1 with no signs of fluid leakage.

Conclusion: The developed microfluidic chip and analysis setup can be used to analyze the viscosity of fluids using very low sample volumes and at very high shear rates. Future work will focus on optimizing the system to further reduce the sample volume requirements to permit testing with human tear samples. This device will provide valuable data in clinical studies investigating dry eye and other ocular surface diseases.

Schulze M, Luensmann D, Ng A, Guthrie S, Woods J, Jones L. Performance of verofilcon A daily disposable contact lenses in digital device users American Academy of Optometry, San Diego, 2022 [ Show Abstract ][ PDF ]

Purpose: To evaluate the performance of Precision1 (verofilcon A) daily disposable (DD) contact lenses (CLs) in habitual CL wearers who undertake substantial digital device use.

Methods: CL wearers between 18-40 years of age who reported a daily digital device use of ≥6 hours while wearing their habitual CLs participated in the study. Eligible participants were dispensed with verofilcon A DD CLs for a period of 12-16 days and were asked to wear these for at least 5 days/week and at least 10 hours/day, while continuing their normal routine of ≥6 hours digital device use. At the 2-week follow-up visit, participants rated their experience with the study lenses on a 0 to 100 scale, with 100 being best, and reported their lens wear times and digital device use. Comfort, dryness and clarity of vision ratings with verofilcon A lenses were collected directly after lens insertion, after 6 hours of digital device use, just before removal, and for overall lens performance. Participants also completed a 4-point (strongly agree, slightly agree, slightly disagree, strongly disagree) Likert scale-based questionnaire. Subjective ratings were not normally distributed, therefore non-parametric analysis was conducted and data are reported as median (range). The Likert scale responses were analyzed using binomial testing.

Results: Thirty-two participants completed the study (27F:5M), mean age of 25.8 ± 6.0 years (range 19-40). Participants reported total and comfortable CL wear time of 14 hours (10-17) and 11.6 hours (2.8-16), respectively, and digital device use of 8.5 hours (6-18) on a typical day. Subjective ratings for overall lens performance after 2 weeks of CL wear were high, with median ratings of 90 (68 – 100) for comfort, 90 (52-100) for dryness and 95 (70-100) for clarity of vision. There were no differences in comfort, dryness and clarity of vision ratings over the course of a typical day, with similar ratings at insertion, after 6 hours of digital device use and just before removal (all p≥0.05). The majority of participants agreed that the study lenses provided good comfort (28/32 subjects; p<0.01) and good vision (29/32; p<0.01) all day long. Considering CL performance when using digital devices for 6 hours, the majority of participants were satisfied with CL comfort (27/32; p<0.01) and vision (29/32; p<0.01) and most agreed that the verofilcon A lenses provided good performance (26/32; p<0.01). Most study participants (24/32; p<0.01) agreed that they did not experience any eye strain during digital device use while wearing verofilcon A lenses. No significant lens-related ocular health findings were observed after 2 weeks of wear.

Conclusions: After 2 weeks of wear, most participants rated the performance of verofilcon A DD CLs highly, with median overall performance ratings for comfort, dryness and vision all 90 on a 0 to 100 scale.

Wulff D, Phan C-M, Jones L. 3D printing using a novel bioink with a commercial mSLA printer to fabricate a model contact lens The Association for Research in Vision and Ophthalmology, Denver, CO, USA, May 2, 2022 [ Show Abstract ]

Purpose: To develop a cost-effective and scalable 3D printing method and novel bioinks to fabricate contact lenses.

Methods: The bioink formulations consisted of GelMA (gelatin methacrylate), LAP (Lithium phenyl-2,4,6-trimethylbenzoylphosphinate), and a yellow food-grade dye. The dye minimizes unwanted light leakage during the photopolymerization process. A commercial mSLA (masked stereolithography) printer, the Photon Mono X (AnyCubic, Shenzhen), was retrofitted with a custom temperature and humidity control kit. The printing process was performed at 40 oC and 90% humidity to ensure that the GelMA remained at a liquid state and to prevent the bioink from drying out, respectively. A set of matrix cubes of varying sizes with holes was used as a standard control. Images of the cubes were taken with a camera, top-down and side-review, analyzed with the ImageJ software and compared with the original CAD designs to derive an overall print quality score. Two print variables, exposure time (5 s to 40 s) and yellow dye concentration (1 – 7%), were analyzed in this study.

Results: The best resolution with the highest print scores were obtained at either 5% yellow dye concentration and 30 seconds exposure time, or 3% yellow dye concentration and 20 seconds exposure time. There was an overall optimal range for both print times (20 - 30 s) and yellow dye concentration (3 - 5%). Values above or below this critical value resulted in lower print quality scores of the standard cubes. A prototype contact lens with a 200 µm thickness was able to be 3D printed using the developed print methods and parameters, with a total print time of approximately 20 minutes. Approximately 28 contact lenses can be printed at the same time using the 3D printer. However, the surface and edges of the 3D printed contact lens were still visually very rough.

Conclusions: The current study demonstrated that a low-cost commercial 3D mSLA printer can be used to fabricate model contact lenses using a hydrogel material. Still, further work is necessary to improve the print quality for fabricating ultra-thin devices such as contact lenses. Future work will use this 3D printing method to fabricate contact lenses for drug delivery.