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Purpose: To examine the effects of long-term ultraviolet radiation (UVR) blocking wearing contact lenses on ocular surface health, eye focus and macular pigment., Method: 210 pre-presbyopic patients were recruited from Birmingham UK, Brisbane Australia, Hong Kong China, Houston USA and Waterloo Canada (n = 42 at each site). All patients had worn contact lenses for ≥ 5 years, half (test group) of a material incorporating a UVR-blocking filter. Ocular health was assessed using slit-lamp biomicroscopy and UV autofluorescence. Accommodation was measured subjectively with a push-up test and overcoming lens-induced defocus. Objective stimulus response and dynamic measures of the accommodative response were quantified with an open-field aberrometer. Macular pigment optical density (MPOD) was assessed using heterochromatic flicker photometry (MPS II)., Results: The two groups of participants were matched for age, sex, race, body-mass-index, diet, lifestyle, UVR exposure, refractive error and visual acuity. Limbal (p = 0.035), but not bulbar conjunctival redness (p = 0.903) was lower in eyes that had worn UVR-blocking contact lenses compared to controls. The subjective (8.0 ± 3.7D vs 7.3 ± 3.3D; p = 0.125) and objective (F = 1.255, p = 0.285) accommodative response was higher in the test group, but the differences did not reach significance. However, the accommodative latency was shorter in eyes that had worn UVR-blocking contact lenses (p = 0.003). There was no significant different in MPOD with UVR filtration (p = 0.869)., Conclusions: Blocking the transmission of UVR is beneficial in maintaining the eye's ability to focus, suggesting that presbyopia maybe delayed in long-term UVR-blocking contact lenses wearers. These lenses also provide protection to the critical limbal region., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Purpose: To determine whether hypo-osmotic saline drops can improve contact lens associated discomfort and dryness by decreasing contact lens osmolality., Methods: Fifteen symptomatic subjects wore Lotrafilcon A lenses bilaterally for 6h on two different days. According to randomisation, hypo-osmotic (280mmol/kg) or hyper-osmotic (380mmol/kg) saline drops were applied four times during each day and ocular symptoms, tear film and contact lens parameters, and contact lens osmolality were assessed., Results: Sixty percent of the subjects preferred the hypo-osmotic saline drops, compared to 33%, who preferred the hyper-osmotic ones. Subjects experienced significantly less dryness and lens awareness with hypo-osmotic saline drops compared to hyper-osmotic ones (p<0.05). Using the hypo-osmotic drops, there was a trend for decreased contact lens osmolality from 379 to 343mmol/kg (p=0.06). There were no differences in lipid layer, non-invasive tear film break-up time, lens surface wettability, lens water content after wear, lens movement on eye or ocular staining and indentation between saline drops (all p>0.05). Interestingly, the difference in contact lens osmolality between drops did not reflect the osmolality difference between the two saline drops., Conclusion: Hypo-osmotic saline drops were preferred by a greater number of subjects and contact lens osmolality tended to be lower with the use of hypo-osmotic saline. Hypo-osmotic drops have the potential to decrease contact lens osmolality which in turn may help improve ocular comfort. This has possible impact on the practitioners' choice of the lens rewetting drop recommended and the design of future lens rewetting drops., (2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To evaluate a novel method to measure the osmolality of worn contact lenses and assess the impact of contact lens and tear film osmolality on comfort during short-term wear., Methods: A new method to measure contact lens osmolality was validated by testing for repeatability and by evaluating independence of lens material, power, and osmolality value of the lens. This method was then used in a clinical study. Nine different lens types were each worn by 15 subjects. Osmolality, tear film, and ocular surface parameters were tested for their association to comfort using linear mixed model., Results: The method to measure contact lens osmolality was independent of lens material (p = 0.911), power (p = 0.826), and osmolality value of the lens (p = 0.858). No differences in contact lens osmolalities between two different days were observed (p > 0.05). Comfort after 6 h of lens wear was associated with the osmolality of the worn lens (p = 0.006, r = -0.41) but not with tear osmolality after lens wear (p = 0.993). Comfort was associated with conjunctival indentation (p = 0.002, r = -0.37). Osmolality of worn lenses significantly correlated with tear film break-up time (p = 0.003, r = -0.22), lens water content (p < 0.001, r = -0.58), conjunctival indentation (p < 0.001, r = 0.45), and ocular sensitivity (p < 0.05) after 6 h lens wear., Conclusion: This newly developed method to measure contact lens osmolality was repeatable and independent of lens material, power, and osmolality value of the contact lens. Although no association between tear film osmolality and ocular comfort after 6 h of lens wear could be demonstrated, contact lens osmolality was associated with comfort and ocular surface characteristics, and may provide the link between symptoms and clinical observations.

Purpose: To investigate the influence of sample volume and contact lens material on osmolality measurements made with a Wescor vapor pressure osmometer., Methods: Accuracy: Sample volumes of 0.8, 2.0, and 10.0 microL were tested with 290, 320, and 1000 mmol/kg after the osmometer was calibrated with the intended sample volume. Influence of sample volume: Sample volumes ranging from 0.5 to 1.1 microL (0.1 steps) were applied with solutions of 290, 320, 500, and 1000 mmol/kg after the osmometer was calibrated with 0.8 microl, independent of the intended sample volume. Influence of contact lens material: Lens discs of 3.4 millimeters were trephined from the center of Lotrafilcon B, Nelfilcon A, Balafilcon A and Etafilcon A lenses, and equilibrated in phosphate buffered saline with 290 mmol/kg after dehydration for 16 h. The osmometer was calibrated with 0.8 microl and lens discs were inserted into the small sample holder of the osmometer., Results: There were no significant differences between the nominal and measured osmolalities for each sample volume and solution combination (all p > 0.05). Influence of sample volume: Differences of more than 0.1 microl between the calibration and sample volume significantly affected osmolality readings, with sample volumes larger than calibration volume resulting in lower readings, and smaller volumes resulting in higher readings. Influence of contact lens material: Measured osmolalities of Lotrafilcon B (358.8 +/- 45.4 mmol/kg) and Balafilcon A (356.7 +/- 38.7 mmol/kg) were not significantly different to each other (p = 0.999) but were significantly higher than Etafilcon A (298.2 +/- 15.9 mmol/kg) and Nelfilcon A (281.2 +/- 12.2 mmol/kg, p < 0.05). There was no significant difference between Etafilcon A and Nelfilcon A lenses (p = 0.056). The main factors associated with measured osmolality were water content, sample volume and their interaction (r(2) = 0.716)., Conclusion: Osmolality readings varied with calibration and sample volume, and with different contact lens materials.

Purpose: Contact lens discomfort remains poorly understood, not least due to lack of associations between clinical signs and symptoms. This study aimed to explore the relationships between osmolarity, comfort and lid wiper epitheliopathy in contact lens wear.Methods: Twenty subjects participated in a randomized, cross-over study where comfilcon A and lotrafilcon A lenses were each worn for 10days separated by a 7days washout period. Tear and contact lens osmolarity, ocular symptoms including comfort, tear stability and production, and lid wiper epitheliopathy were measured.Results: Comfort and tear stability decreased and upper lid wiper staining and foreign body sensation increased with lens wear. These were not affected by lens type. A reduction in tear production was seen after 10days of comfilcon A lens wear. High proportions of lid wiper epitheliopathy were observed at the upper (range 65%-85%) and lower (range 90%-100%) lid margins. Tear and contact lens osmolarity were unaffected by lens wear or type. Contact lens osmolarity was associated with comfort (r=0.45, p=0.009). Tear osmolarity moderately correlated with tear stability (r=-0.53, p=0.014) and tear production (r=-0.44, p=0.012) but not with lid wiper staining.Conclusions: A relationship between comfort and contact lens osmolarity and between tear osmolarity and tear stability and production were found, however, this study was unable to demonstrate an association between comfort and tear osmolarity or lid wiper epitheliopathy. Further studies using contact lenses with a wider range of comfort responses are warranted to investigate these associations further. [ABSTRACT FROM AUTHOR]