ABSTRACT
CLINICAL RELEVANCE: Accurate colour vision assessment is important in clinical settings to minimise false-positive errors and enhance the reliability of diagnoses outcomes. BACKGROUND: Colour vision testing is valuable in assessing the visual system, particularly given the high proportion of individuals with poor vision. This study aimed to determine the minimum visual acuity level required to perform a colour-vision test without errors. METHODS: After fogging the right eyes of 52 healthy participants using plus lenses to 1.60 logMAR, vision was evaluated using Ishihara, Hardy - Rand - Rittler Standard Isochromatic, Waggoner Pseudo-isochromatic, City University, Waggoner Computerised, and Farnsworth D-15 tests. Participants then completed these tests at lower fogging degrees (in 0.1-logMAR intervals). The acuity at which 5% of the tested population was considered abnormal was determined. RESULTS: Significant differences were found in the average visual acuity required to perform colour vision tests without errors (p < 0.05). The Waggoner Computerized test required the highest average visual acuity among the tests utilised. The Farnsworth D-15 test yielded the highest logMAR values. No significant differences were observed between the Waggoner Pseudo-isochromatic test and Hardy - Rand - Rittler Standard Isochromatic, Ishihara, and Farnsworth D-15 tests (p > 0.05). Additionally, no significant differences were found between the Ishihara and Hardy - Rand - Rittler tests (p > 0.1) or between the Waggoner Computerized and City University tests (p = 0.11). Colour vision testing maintained an accuracy ≤ 1.0 logMAR with the Ishihara and Hardy - Rand - Rittler tests, 1.1 logMAR with the Waggoner Pseudo-isochromatic and Farnsworth D-15 tests, and 0.9 logMAR with the Waggoner Computerized and City University tests. CONCLUSIONS: Insights are provided into the visual acuity thresholds required for accurate colour vision testing, which can serve as a basis for future research and provide a reference for clinical practice in this field.
ABSTRACT
PURPOSE: Colors have been shown to improve reading performance; however, the effect of colors on Arabic orthography has not been studied. This study aimed to design and create a chromatic acuity chart to evaluate the effect of chromatic contrast on Arabic reading performance. METHODS: Color selection for the newly developed chromatic acuity chart was based on the contrast between the L, M, and S cones. The colors were chosen to have a luminance of approximately 13.6 cd/m2 with red text on a green background. A Pantone color guide set was used to choose the colors. Fifteen healthy individuals aged 19-27 years were recruited. Reading performance was measured using the newly developed red-green (R-G) chart and compared with the original achromatic Balsam Alabdulkader-Leat (BAL) chart with a luminance of 95 cd/m2. The outcomes were maximum reading speed in standard-length words per minute (SLWPM), reading acuity (RA), and critical print size (CPS). RESULTS: The mean R-G SLWPM of 201 wpm was similar to that of the BAL chart (P < 0.05). The mean RA for the R-G chart was - 0.05 logMAR and - 0.20 logMAR for the BAL chart (P < 0.05). The CPS for the R-G chart was 0.36 logMAR, significantly higher than the original chart of 0.17 logMAR (P < 0.05). CONCLUSION: This study showed that the reading performance for a text that varies only in chromatic contrast along the R-G axis reduces the reading performance for CPS and RA. Individuals showed an approximate decline of two lines on an Arabic continuous text chart compared with a high-contrast achromatic chart. This information can be used to further develop a set of near-reading charts that can efficiently determine whether there is a differential loss in chromatic and achromatic sensitivity in patients with various vision disorders.
ABSTRACT
COVID-19 is a highly contagious disease caused by SARS-CoV-2. Vaccination against the virus was first approved in Saudi Arabia in December 2020. Vaccinated individuals are still at risk of getting infected with the virus and can transmit the disease. Therefore, the perception of vaccinated individuals regarding the disease can help limit the spread of the virus. OBJECTIVES: To measure the risk perception of COVID-19 following vaccination and factors that have an effect on risk perception; to identify the health protective behaviours of the vaccinated individuals. METHODOLOGY: This is a quantitative analytical cross-sectional, questionnaire-based study. The target population includes individuals aged 18 and above who live in the Riyadh region and have been vaccinated, during the period of June 2021 to December 2021. RESULTS: The perception of 30.2% of participants did not change after vaccination, with many participants continuing to "always" take precautions even after vaccination. Numerous factors, such as age, gender, marital status, occupational status, employment status, and total household income, have shown significant effects towards risk perception. CONCLUSION: Many vaccinated individuals have continued to take precautionary steps and their risk perception has not changed.
