Correction: The evaluation of a web-based tool for measuring the uncorrected visual acuity and refractive error in keratoconus eyes: A method comparison study.

[This corrects the article DOI: 10.1371/journal.pone.0256087.].

The evaluation of a web-based tool for measuring the uncorrected visual acuity and refractive error in keratoconus eyes: A method comparison study.

PURPOSE: To evaluate the outcome of a web-based digital assessment of visual acuity and refractive error, compared to a conventional supervised assessment, in keratoconus patients with complex refractive errors. MATERIAL AND METHODS: Keratoconus patients, aged 18 to 40, with a refractive error between -6 and +4 diopters were considered eligible. An uncorrected visual acuity and an assessment of refractive error was taken web-based (index test) and by manifest refraction (reference test) by an optometrist. Corrected visual acuity was assessed with the prescription derived from both the web-based tool and the manifest refraction. Non-inferiority was defined as the 95% limits-of-agreement (95%LoA) of the differences in spherical equivalent between the index and reference test not exceeding +/- 0.5 diopters. Agreement was assessed by a Bland-Altman analyses. RESULTS: A total of 100 eyes of 50 patients were examined. The overall mean difference of the uncorrected visual acuity measured -0.01 LogMAR (95%LoA:-0.63-0.60). The variability of the differences decreased in the better uncorrected visual acuity subgroup (95%LoA:-0.25-0.55). The overall mean difference in spherical equivalent between the index and reference test exceeded the non-inferiority margin: -0.58D (95%LoA:-4.49-3.33, P = 0.008). The mean differences for myopic and hyperopic subjects were 0.09 diopters (P = 0.675) and -2.06 diopters (P<0.001), respectively. The corrected visual acuities attained with the web-based derived prescription underachieved significantly (0.22±0.32 logMAR vs. -0.01±0.13 LogMAR, P <0.001). CONCLUSIONS: Regarding visual acuity, the web-based tool shows promising results for remotely assessing visual acuity in keratoconus patients, particularly for subjects within a better visual acuity range. This could provide physicians with a quantifiable outcome to enhance teleconsultations, especially relevant when access to health care is limited. Regarding the assessment of the refractive error, the web-based tool was found to be inferior to the manifest refraction in keratoconus patients. This study underlines the importance of validating digital tools and could serve to increase overall safety of the web-based assessments by better identification of outlier cases.

Validation of an Independent Web-Based Tool for Measuring Visual Acuity and Refractive Error (the Manifest versus Online Refractive Evaluation Trial): Prospective Open-Label Noninferiority Clinical Trial.

BACKGROUND: Digital tools provide a unique opportunity to increase access to eye care. We developed a Web-based test that measures visual acuity and both spherical and cylindrical refractive errors. This test is Conformité Européenne marked and available on the Easee website. The purpose of this study was to compare the efficacy of this Web-based tool with traditional subjective manifest refraction in a prospective open-label noninferiority clinical trial. OBJECTIVE: The aim of this study was to evaluate the outcome of a Web-based refraction compared with a manifest refraction (golden standard). METHODS: Healthy volunteers from 18 to 40 years of age, with a refraction error between -6 and +4 diopter (D), were eligible. Each participant performed the Web-based test, and the reference test was performed by an optometrist. An absolute difference in refractive error of <0.5 D was considered noninferior. Reliability was assessed by using an intraclass correlation coefficient (ICC). Both uncorrected and corrected visual acuity were measured. RESULTS: A total of 200 eyes in 100 healthy volunteers were examined. The Web-based assessment of refractive error had excellent correlation with the reference test (ICC=0.92) and was considered noninferior to the reference test. Uncorrected visual acuity was similar with the Web-based test and the reference test (P=.21). Visual acuity was significantly improved using the prescription obtained by using the Web-based tool (P<.01). The Web-based test provided the best results in participants with mild myopia (ie, <3 D), with a mean difference of 0.02 (SD 0.49) D (P=.48) and yielding a corrected visual acuity of >1.0 in 90% (n=77) of participants. CONCLUSIONS: Our results indicate that Web-based eye testing is a valid and safe method for measuring visual acuity and refractive error in healthy eyes, particularly for mild myopia. This tool can be used for screening purposes, and it is an easily accessible alternative to the subjective manifest refraction test. TRIAL REGISTRATION: Clinicaltrials.gov NCT03313921; https://clinicaltrials.gov/ct2/show/NCT03313921.

Quality of life in relation to constipation among opioid users.

OBJECTIVE: Opioid users often experience constipation. In this study the impact of constipation on QoL was assessed in patients using opioids either for non-advanced illness or advanced illness. METHODS: Patients using opioids, recruited via public pharmacies, were asked to complete questionnaires on opioid use, constipation and the EuroQol five-dimension questionnaire (EQ-5D). Patients with a severe non-curable disease and relatively short life-expectancy were classified as having an advanced illness; a disabling yet not directly life-threatening condition was defined as non-advanced illness. Constipation was assessed based on questions on opioid side-effects and laxative use. EQ-5D index scores were compared between patients with and without constipation using Wilcoxon two-samples test. RESULTS: Questionnaires were returned by 588 patients with non-advanced illness, of whom 326 (55%) were classified as having constipation and by 113 patients with advanced illness, of whom 76 (67%) were classified as having constipation. The median EQ-5D index, a weighted health state index score with 1 = full health, was lower in patients with constipation than in patients without constipation (0.31 vs. 0.65, p< 0.01 for non-advanced illness and 0.41 vs. 0.61, p=0.12 for advanced illness). CONCLUSION: The results of this study suggest that, in patients using opioids either for non-advanced illness or advanced illness, constipation negatively influences QoL. By separately analysing patients with advanced illness and patients with non-advanced illness, possible selective non-response and confounding was accounted for, but not completely solved.