BackgroundSustained digital display viewing reduces eye blink frequency and tear film stability. To retain water and preserve a smooth optical surface, contact lens manufacturers have integrated the humectant polyvinylpyrrolidone (PVP) into silicone hydrogel contact lenses. In this study, extended blink time (EBT) was used to assess visual stability over a prolonged blink interval of two PVP-containing silicone hydrogel lenses, samfilcon A (SAM) and senofilcon A (SEN).Materials and methodsThis randomized, bilateral, masked, crossover study assessed lens performance in ten subjects after 16 hours of wear. EBT, ie, the time elapsed between cessation of blinking and blur-out of a threshold letter on the acuity chart, was measured. At the end of the wear period, subjects reported duration of computer use and rated visual quality (VQ) and comfort while wearing the assigned lens, and the investigator evaluated lens surface wetting characteristics. Each lens was removed and immediately weighed to determine total water content.ResultsEBTs were 10.42 seconds for SAM and 8.04 seconds for SEN (p = 0.015). Subjective ratings of VQ after 16 hours of wear were 84.6 for SAM and 74.4 for SEN (p = 0.049). Comfort ratings were 85.9 for SAM and 80.2 for SEN (p > 0.05). Median times of computer use were 6–8 hours for both lens types. Post blink, 70.0% of SAM and 30.0% of SEN lenses were completely wet (p = 0.021). Total water content after wear was 43.7% for SAM and 35.5% for SEN (p < 0.001).ConclusionEBT measurement indicated more stable vision with the PVP-containing SAM polymer compared with the PVP-containing SEN polymer. The SAM polymer also demonstrated better surface wetting and maintained higher water content after a prolonged period of wear. EBT can be valuable in assessing vision stability of patients after hours of computer use.

Background: Addressing contact lens dryness continues to be a development goal of contact lens (CL) manufacturers. Objective: The objective of this study is to evaluate the clinical performance of kalifilcon A, a daily disposable silicone hydrogel (SiHy) CL, in subjects that experience dryness with their habitual planned-replacement SiHy CLs relative to a non-dry subgroup. Methods: A cohort of adapted planned-replacement SiHy CL wearers wore kalifilcon A lenses for at least 8 hours daily over two weeks. After one week of lens wear, subjects completed a survey regarding their lens wearing experience with respect to comfort and vision. Subsequently, subjects visited the clinics for the 2-week visit, during which the investigators completed a slit lamp exam and questionnaire regarding lens performance. Results: The evaluation included 180 subjects experiencing CL dryness with their habitual SiHy lenses and 213 subjects that did not. Both subgroups largely agreed with all comfort and vision attribute statements, and the dryness subgroup expressed higher levels of agreement with most comfort-related statements. Among habitual rewetting drop users, 73.9% in the dryness subgroup and 73.1% in the non-dry subgroup used drops less frequently while wearing kalifilcon A lenses. Investigators found no > Grade 2 slit-lamp findings, nor differences between subgroups. Neither subgroup showed a change in ratings between visits, except for a significantly higher proportion of improvers in the non-dry subgroup for upper lid tarsal conjunctival abnormalities. Conclusion: The kalifilcon A lens performed well among habitual planned-replacement SiHy CLs wearers. Its unique chemistry can provide a more satisfying wear experience for SiHy lens wearers experiencing CL dryness.

No abstract

This study was undertaken to 1. develop an apparatus to rapidly measure coefficient of friction (COF) on soft contact lenses; 2. determine if COFs measured on two daily-disposable lens models before and after wear are consistent with changes in lens surface morphology observed in parallel atomic force microscopy (AFM) images. Methods: A stress rheometer was adapted to measure COF on a soft contact lens by custom fabrication of a rapid-mount sample stage for increased throughput. Five subjects were randomly assigned to wear daily disposable nesofilcon A and delefilcon A contact lenses bilaterally for 4 hours, after which time lenses were removed. Static and kinetic COFs of lenses worn on left eyes was measured, while lenses worn on right eyes were imaged in parallel by AFM in tapping mode. Root mean square (RMS) surface roughness was calculated for all lenses to determine the effect of wear on surface topography. Results: Both static and kinetic COFs measured on unworn delefilcon A silicone hydrogel lenses were greater than on nesofilcon A traditional hydrogel lenses. Static COF on nesofilcon A increased significantly after wear, while kinetic COF trended higher but did not change significantly. Similarly, static COF on delefilcon A also increased significantly after wear, and kinetic COF trended higher but did not change significantly, both remaining greater than on worn nesofilcon A. Parallel AFM analysis demonstrated that nesofilcon A lenses are smoother than are delefilcon A out of the package. Both lenses attracted deposits during wear, but the nesofilcon A surface was less altered by on-eye wear than was the delefilcon A surface. Conclusion: A system to rapidly measure static and kinetic COFs was successfully developed. Static and kinetic COFs measured on delefilcon A were greater than on nesofilcon A lenses. More deposits and greater surface roughness were observed after wear on delefilcon A relative to nesofilcon A. Parallel AFM images of worn and unworn lenses were not predictive of measured COFs, but increased roughness visible by AFM was consistent with observed increases in COF, although not all increases were statistically significant.

Purpose The objective of this study was to evaluate and compare the clinical performance of samfilcon A, a unique, polyvinylpyrrolidone (PVP)-containing, silicone hydrogel contact lens with that of the balafilcon A silicone hydrogel contact lens when worn on a 7-day extended wear basis. Subjects and Methods A total of 669 subjects completed this 12-month, controlled, parallel group, masked, randomized study; of these, 340 wore samfilcon A lenses and 329 balafilcon A lenses. Subjects wore their respective assigned lenses bilaterally on a 7-day extended wear basis. On the seventh night of each wearing week, lenses were removed, cleaned, and disinfected using Biotrue multi-purpose solution (MPS), then re-inserted the following morning. Lenses were replaced with new lenses monthly. At each follow-up visit, investigators completed a slit lamp evaluation, and subjects rated lenses based upon a predefined set of performance criteria. Results The samfilcon A lens performed comparably to the balafilcon A lens in terms of most graded and ungraded slit lamp findings, differing significantly only for corneal staining Grade 2 or greater, which favored samfilcon A, and anterior segment abnormalities, which favored balafilcon A. Subjects rated both lenses highly when queried about various lens-wearing characteristics. When comparing the number of subjects with findings on either eye on at least one follow-up visit, the two lenses were comparable in many aspects but favored samfilcon A with respect to cleanliness upon removal, overall comfort, comfort at end of day, dryness, vision, vision in low light, vision at end of day, and overall impression (all p < 0.05). Conclusion While subjects rated both highly, samfilcon A lenses worn for 7-day extended wear and replaced on a monthly basis performed comparably to or better than balafilcon A lenses when worn for the same 7-day wear time and replacement cycle.