Snellen iPad App versus Traditional Light-Box Snellen Chart in Distance Visual Acuity.

This study aimed to discover distance visual acuity (VA) assessments through the display of the Snellen chart on the iPad tablet. The findings are equivalent to those obtained using the conventional light-box Snellen chart. In this work, the Snellen iPad app and Eye Chart HD iOS app are utilized among the participants in the Ophthalmology Outpatient Department (OPD) for determining VA. A cross-sectional method was used for the examination, which included 100 new patients who were chosen by random selection. The age requirement for new patients was 8 years and up for both genders. Patients with a VA of less than 6/30 were disqualified from the experiment. Two testing modalities are used to measure VA, such as the iPad Mini 2 with the iOS software Eye Chart HD and the classic Snellen light-box chart. The observation revealed that the Snellen iPad app and the classic light-box Snellen chart produced equivalent findings. The classic Snellen chart may have been memorized by participants before their eye examination, undermining the accuracy of the conclusions of the initial testing modality used. Patient-related variables were also identified as confounders. Future studies should adjust the brightness of the iPad Mini 2 and the traditional light-box Snellen chart to make sure that neither experiment modality's brightness affects the accuracy of the findings. Future research should also investigate the use of premium apps, use both devices, and employ a bigger sample size.

Clinical usefulness of the baby vision test in young children and its correlation with the Snellen chart.

AIM: To investigate the efficacy of a new visual acuity (VA) screening method, the baby vision test for young children. METHODS: A total 105 eyes of 65 children aged 2-8y were included in the study. Acuity testing was conducted using a standardized recognition acuity chart (Snellen visual chart: at 3 m) and the baby vision model assessment. The baby vision device includes a screen, a near infrared camera and a computer. Children were seated at a measured distance of 33-40 cm from a display for testing. VA was estimated according to the highest resolution the children could follow. Decimal VA data were converted to logarithm of the minimum angle of resolution (logMAR) for statistical analysis. The VA results for each child were recorded and analyzed for consistency. RESULTS: The mean VA measured using the Snellen visual chart was 0.62±0.32, and that assessed using the baby vision test was 0.66±0.27. The 95% limit of agreement was -0.609 to 0.695, with 95.2% (100/105) plots within the 95% limits of agreement. VA values of the baby vision test were significantly correlated with those of the Snellen chart (R=0.274, P=0.005). CONCLUSION: The baby vision test can be used as a relatively reliable method for estimating VA in young children. This new acuity assessment might be a valid predictor of optotype-measured acuity later in preverbal children.

Visual Acuity Examination Methodology in Keratoconus.

Visual acuity is one of the most important parameters for evaluating the vision of patients with keratoconus. This study reviewed 295 articles related to keratoconus published between 2017 and 2022 in which visual acuity was one of the parameters measured. The methodology of visual acuity testing in studies on keratoconus was thoroughly analyzed. The analysis showed that the most commonly indicated chart for testing visual acuity papers on keratoconus is the Snellen chart. It was shown that in 150 out of 295 articles, the authors do not describe the methodology for testing visual acuity. What is more, it was also shown that in 68 of the 295 articles which were analyzed, a procedure for converting visual acuity tested with a Snellen chart into a logMAR scale was used. In this review, we discuss the validity and reliability of such conversions. In particular, we show that insufficient description of visual acuity testing methodology and lack of information on the conversion of visual acuity results into the logMAR scale may contribute to the misinterpretation of visual acuity test results.

HAS SNELLEN CHART LOST THE BATTLE TO ETDRS IN CATARACT SURGERY VISUAL ACUITY EVALUATION?

This study was designed to explore practical differences between visual acuity (VA) scores measured on Snellen chart versus ETDRS chart, to grade cataracts using LOCS III system, and to compare VA on both charts depending on cataract grade and type. Prospective evaluation of uncorrected and best-corrected visual acuity was carried out on the eye scheduled for cataract surgery preoperatively and postoperatively on the Snellen and ETDRS charts. The study was carried out at Department of Eye Diseases, Clinical Center of Serbia, during a two-year period. Inclusion criteria were met by 540 patients who underwent testing, surgery, data collection and analysis. The mean VA score was better on ETDRS than on Snellen chart. The mean difference was 6.05 letters or 1.21 lines. VA results correlated with all types of cataract regardless of the chart used, with the highest statistical significance (p<0.0001) for subcapsular cataract. The ETDRS chart was found to be more discriminative and precise than Snellen chart, especially for poor VA.

Is LEA symbol better compared to Snellen chart for visual acuity assessment in preschool children?

Aim: To compare visual acuity using the LEA symbol chart with Snellen E test chart in preschool children of age 3-5 years. Patients and methods: Inclusion criteria: 50 emmetropic children aged 3 to 5 years. Exclusion criteria: Strabismus, amblyopia, ametropia, and any organic eye disease. A pseudo randomized protocol was used to test visual acuity (VA) in each subject monocularly on both eyes using Snellen E chart and LEA symbol chart. Visual acuity for both charts was scored as smallest optotype size which the child correctly identified 3 of maximum 4 optotypes. The strength of agreement on VA between two charts was tested using Interclass correlation coefficient (ICC). A Mann-Whitney U test was applied to compare both the groups. Results: Boys: Girls = 26:24 with a mean age and standard deviation of 4.12 + 0.79 years. ICC between Snellen's and LEA symbol chart was 0.256 and 0.213 for right and left eye respectively. Analysis of the two samples using Mann-Whitney test showed a significant difference between the two charts (p value <0.000). Conclusion: LEA symbol test showed only a fair agreement with Snellen E charts for visual acuity measurements. Visual acuity measurement with LEA symbol chart showed significantly higher scores as compared to Snellen's chart.

[Visual acuity assessment: historical overview and current trends]. / Otsenka ostroty zreniia: vzgliad v proshloe i sovremennye tendentsii.

The article reviews the evolution of visual acuity assessment and gives comparison of the visual acuity charts (Snellen vs. ETDRS) widely used in research and clinical practice.

Visual Acuity Testing Before and After Intravitreal Injection of rAAV2-ND4 in Patients.

Gene therapy in ophthalmology has developed rapidly, and there has been a breakthrough in the treatment of Leber's hereditary optic neuropathy. After receiving an intravitreal injection of rAAV2-ND4, patients followed up over a certain time period showed a definite increase in visual acuity. Visual acuity testing is critical for assessing the efficacy of rAAV2-ND4 intravitreal injection.

Contribution of sVEP visual acuity testing in comparison with subjective visual acuity.

AIMS: Visual acuity determination is an important task in ophthalmology and optometry practices. Visual acuity can be examined objectively or subjectively. The objective examination method, sVEP, allows for quick objective measurements of patient's visual acuity. Previous studies have not demonstrated the repeatability of this objective sVEP method. This study aims to evaluate the sVEP method and compare it to a subjective method. METHODS AND RESULTS: The sample was divided into two groups. For the first group, visual acuity was measured with sVEP and Snellen methods on only one patient twelve times. In the second group, visual acuity was measured twice with sVEP followed twice with the Snellen method with Landolt's rings and logMAR modification on 32 non-pathological patients. Results showed significant differences between average values of visual acuity obtained with both methods (sVEP and Snellen) in both samples (T-test, P < 0.01; Wilcoxon test, P = 0.02 in second group). In the second group, significant correlations between repeated sVEP measurements (Spearman test, P < 0.05, r = 0.69) were found but no significant correlation between average sVEP measurement and average Snellen measurement (Spearman test, P > 0.05, r = 0.15) was found. CONCLUSION: Objective measurement of visual acuity with sVEP is a valid and reliable method, but is recommended only when it is not possible to use a subjective method for measuring visual acuity, e.g. children, patients with mental retardation or simulating/dissimulating patients.

Reproducibilidad y concordancia para la carta snellen y lea en la valoración de la agudeza visual en infantes de primaria / Test-retest reliability and agreement for snellen and lea visual chart to assessment visual acuity in elementary school children

Introducción: la evaluación de la visión de un infante se determina empleandolas cartas de agudeza visual, aunque se les conoce comúnmente con el nombre de “optotipos”, de las cuales la más frecuentemente empleada es la Snellen.Objetivo: determinar la reproducibilidad inter observadores y la concordancia dedos test que miden la agudeza visual en infantes escolares. Materiales y métodos: se evaluaron 61 niños (122 ojos) visualmente sanos conedades entre los 6 a10 años de un colegio de la ciudad de Pereira. La agudeza visual (AV) fue valorada con una carta Snellen de letras y con una carta LEA por parte de dos evaluadores independientemente. Resultados: la AV promedio fue de 0.0 unidades del logaritmo del mínimo ángulo de resolución (logMAR) (20/20) y la diferencia media entre los test fue -0.05 (IC95 porciento-0.064 a -0.037) logMAR; el coeficiente de reproducibilidad (COR) fue mejor parala carta LEA que Snellen (±0.08 y 0.12) superior a lo reportado en estudios previos (±0.15).Conclusión: la concordancia con el coeficiente de correlación intraclase mostró ser moderada (0.493) y los límites de acuerdo mostraron que había una mayor variación entre las mediciones para cuando la AV era más alta. Las cartas LEA y Snellen mostraron una buena reproducibilidad, no obstante la variabilidad en las mediciones entre ellas indica que no son pruebas intercambiables.

Introduction: the evaluation of the vision of an infant is determined using the visual acuity charts, although they are commonly referred to as the “optotypes”, of which the most frequently used is the Snellen.Objetive: to determinate test retest reliability and the agreement of two tests used to assess elementary school children visual acuity. Methods: we evaluated 61 visual healthy children (122 eyes) ages 7 through 10enrolled in elementary school of Pereira. Visual acuity (VA) was measured with Snellen letters chart and LEA symbols chart by two evaluators.Results: the average of VA was 0.0 of logarithm of minimum angle of resolution(logMAR), the mean difference between the test was -0.05 (CI95% -0.064 to -0.037) logMAR; the coefficient of repeatability (COR) was better for LEA symbols and Snellen chart (±0.08 and 0.12) than those reported in previous papers (±0.15). Conclusion: the coefficient correlation Intraclass (CCI) has indicated a moderateconcordance (0.493) and the 95% limits of agreement showed a wider difference between the both charts measurements as while visual acuity was better. LEA symbols and Snellen chart have showed good test retest reliability, although the variability between both measurements indicates that they are not interchangeabletest.

Prueba piloto para determinar la reproducibilidad de la carta de Snellen al evaluar la agudeza visual en sujetos jóvenes / Pilot trial to determine the reliability of the snellen chart for assessment of the visual acuity in young people

La agudeza visual es la principal característica evaluada para conocer cómo ve una persona. Al medirla se utilizan Cartas de Agudeza Visual, de las cuales la más empleada en el medio colombiano es la carta Snellen. Objetivo: el propósito de esta investigación fue determinar la reproducibilidad ínter e intraobservador de la carta de letras serif Snellen para evaluar la agudeza visual (AV). Materiales y métodos: en un muestreo por conveniencia, dos evaluadores midieron en dos sesiones la AV con la carta de Snellen tipo serif en 110 estudiantes universitarios (220 ojos) entre 15 y 30 años de edad, con ametropía corregida, visión binocular normal y sin patologías del segmento anterior o posterior. Se repitieron las pruebas en los pacientes induciendo una miopía de 1,50 D. Los valores de AV fueron convertidos de la escala fraccional a la logarítmica. Resultados: los resultados mostraron que la AV promedio (LogMAR) fue -0,06 (20/20+5); con la miopía inducida, 0,51 (20/63). La prueba de Wilcoxon pareada mostró diferencias significativas para la primera sesión entre los dos evaluadores (p = 0,0001; p = 0,007) y con el defecto inducido interevaluadores en las dos sesiones (p = 0,03; p = 0,001). El coeficiente de correlación y concordancia de Lin (Pc) indicó pobre concordancia (Pc = 0,9) ínter e intraobservador, sin defecto inducido y con éste. Los límites de concordancia de Bland-Altman muestran variaciones de AV de 3 líneas en los sujetos corregidos y de 5 a 6 líneas de visión con la miopía inducida. Conclusiones: la carta de Snellen presenta concordancia baja y variabilidad en los resultados moderada-alta, por lo que se sugiere la realización de estudios que evalúen la validez de la prueba en las poblaciones sana y con alteraciones visuales.

The visual acuity is the main characteristic evaluated to know how a person sees. For the visual acuity measuring it is used the letter chart, in Colombia the most used it is the Snellen Chart. Objective: To determinate the reliability inter e intraevaluator of Snellen Chart to test visual acuity. Methods: With convenience sampling two evaluators tested visual acuity with serif Snellen Chart to 110 subjects (220 eyes) who were university students between 15-30 years old, full distance refractive correction, normal binocular vision, and no pathologies of anterior and posterior of eye. A refractive error (myopia 1.50D) was induced for all the subjects and the trials were carrying out.Results: Visual acuity means was -0.06 (20/20+5), with induced myopia 0.51 (20/63). Wilcoxon sign rank test showed difference between inter evaluators (p=0,0001; p=0,007) in first trial and wearing plus lens +1.50D between inter evaluators in both trials ((p=0,03; p=0,001). Conclusions: Correlation Coefficient and Concordance of Lin showed a poor concordance and a moderated-high variability in the outcomes; then, Snellen chart has a poor concordance and moderate variability, so we suggest achieving researches about the validity of this test in the population with normal and subnormal vision.

Epidemiology of hospitalized ocular injuries in the upper East region of ghana.

UNLABELLED: Summary AIM OF STUDY: The Upper East is the poorest and most rural region in Ghana and ocular injuries are a major public health problem. This study aims at providing epidemiologic data on the burden of this problem in order to facilitate the provision of integrated eye care and safety strategies for the prevention of such injuries in the region. DESIGN: A retrospective case series. METHODS: Computerized records of all eye injuries admitted to the clinic between January and December 2004 were retrieved and analyzed using the Epi-Info software. Injuries were classified using the Birmingham Eye Trauma Terminology while Snellen visual acuities were classified/banded using the WHO categories of visual impairments. RESULTS: Ninety six eyes of 96 patients were admitted over the study period. Seventy five percent of the patients were males and 82.3% below the age of 30 years. Half of the patients had to travel beyond 100 km to get ophthalmic assistance. Only one third of the cases reported within 24 hours while 21% reported after one week of their injuries. These delayed periods of reporting showed no statistically significant relationship with the distances travelled to the hospital (p=0.76; chi2 test), nor the eventual visual outcome achieved following treatment. Open-globe injuries were by far the most common (60/96) and were 4.7 times more likely (Chi squared test) to produce poor visual outcome (p=0.02 CL 1.75-12.63). CONCLUSION: Current eye care strategies do not adequately address the issue of eye injuries in the region. There is the need to provide integrated approach by incorporating primary eye care strategies into the existing primary health care system.