Near visual function measured with a novel tablet application in patients with astigmatism

Clinical relevance: While the clinical focus of performance metrics is traditionally based on visual acuity, research from the field of visual impairment has demonstrated that metrics such as reading speed and critical print size correlate much more strongly with subjective patient reported outcomes and assessed ability in real-world tasks. Background: More recently, digital device use has increasingly replaced many paper-based tasks. Therefore, this study aimed to assess the correlation between standard acuity/contrast metrics and functional reading ability compared to real-world performance on an iPad-based reading task with astigmatic patients corrected wearing toric and mean spherical equivalent contact lenses. Methods: Thirty-four adult participants, with −0.75 to −1.50 D of refractive astigmatism, were enrolled in a double-masked cross-over study and fitted with toric and spherical equivalent contact lenses, in random order. A digital application was developed to assess zoom, contrast modifications, the distance at which the tablet was held, blink rate, and time to complete the reading task. High and low contrast near logMAR visual acuity were measured along with reading performance (critical print size and optimal reading speed). Results: The amount participants chose to increase tablet font size (zoom) was correlated with their high-contrast visual acuity with toric correction (r = 0.434, p = 0.010). With best sphere correction, zoom was associated with reading speed (r = −0.450, p = 0.008) and working distance (r = 0.522, p = 0.002). Text zoom was also associated with horizontal (toric: r = 0.898, p < 0.001; sphere: r = 0.880, p < 0.001) and vertical scrolling (toric: r = 0.857, p < 0.001; sphere: r = 0.846, p < 0.001). There was a significant negative association between the selection of text contrast and zoom (toric: r = −0.417, p = 0.0141; sphere: r = −0.385, p = 0.025). Conclusion: Real-world task performance allows more robust assessment of visual function than standard visual metrics alone. Digital technology offers the opportunity to better understand the impact of different vision correction options on real-world task performance

Tear Exchange and Midday Fogging

Purpose: Approximately 30% of scleral gas-permeable lens (SGP) wearing patients are affected by midday fogging (MDF). The purpose of this study was to determine the influence of post-lens tear exchange and other fitting characteristics on the presence or absence of MDF.Methods: 33 subjects were recruited for this study. 23 subjects were habitual SGP wearers (11 MDF, 12 non-MDF subjects), and 10 were non-SGP wearing normal controls. At the study visit, dry eye symptoms were quantified (TERTC DryEye Questionnaire), and lens-fitting characteristics were evaluated using ocular coherence tomography and biomicroscopy. Tear exchange rates were measured using the Fluorotron fluorophotometer. The procedure was to instill high molecular weight fluorescein(FITC) Dextran into the tear film reservoir beneath the SGP, and measure the tear fluid fluorescein concentration every 5-30 minutes over a period of 4 hours. The tear reservoir fluorescein concentrations were plotted to measure the fluorescein decay from within the tear fluid, which was used to calculate the tear exchange rate. Statistical analysis was done using student t-test and ANOVA.Results: In this study, there was less tear exchange in the MDF group (mean: 0.111%) when compared to the nonMDF group (mean: 0.417%), although statistical significance was not reached due to the high variability of the exchange rates (p = 0.26). There was no significant difference between the tear film reservoir thickness in the MDF (283um) and nonMDF (326um)groups (p = 0.53), or with dry eye scores (mean of 29.5 in MDF, 30.4 in nonMDF) (p = 0.91).Conclusions: In this study, there is no clear relationship between the amount of tear exchange during SGP wear and the incidence of MDF. Tear exchange may indeed be a factor, although additional studies are needed to clarify its role, and to further explore other contributing factors that may be involved in modulating the occurrence of MDF.Optometry, College o

Soft toric contact lens wear improves digital performance and vision—A randomised clinical trial

Purpose To compare objective and subjective digital near visual performance and comfort in low to moderate astigmatic participants fitted with toric versus spherical equivalent silicone hydrogel daily disposable contact lenses. Methods This was a double-masked, randomised, crossover study. Participants aged 18 to 39 years with astigmatism of −0.75 to −1.50 D were recruited and fitted with toric and spherical contact lenses, in random order. Outcomes were measured at baseline and after 1 week of wear with each contact lens type after the follow-up visits. High- and low-contrast near logMAR visual acuity, automated visual acuity, zoom (%), contrast (%), reading distance (cm), critical print size (logMAR) and reading speed were assessed. Participants also completed the validated Near Activity Visual Questionnaire (NAVQ) and Contact Lens Dry Eye Questionnaire 8 (CLDEQ-8) for each correction type. Results Twenty-three participants completed the study (74% female, average age 24.4 ± 4.2 years). When participants wore toric contact lenses, near high- and low-contrast visual acuity and automated visual acuity improved by 3–4 letters (all p < 0.03) and participants were able to read faster on an iPad (p = 0.02). Participants were also able to read with 8% less contrast on the iPad with toric lenses (p = 0.01). Participants reported better subjective vision on the overall NAVQ (p = 0.001) and better comfort on the CLDEQ-8 (p = 0.02) with toric lenses. Fewer participants reported difficulty with maintaining focus at near, reading small print, reading labels/instructions, reading the computer display/keyboard and reading post/mail with toric correction. Conclusions Toric contact lenses improve comfort, subjective and objective visual performance with digital devices and other near tasks compared with the spherical equivalent correction in participants with low to moderate astigmatism