Validation of Titmus vision screener V4 for diagnosing refractory errors and colour blindness: An analogy with quotidian.

Background: This study aims at evaluating the validity profile of Titmus vision screener V4 for gauging visual acuity and colour perception as a screening tool. Methods: Eleven hundred young adults attending eye OPD at a tertiary care center were included in the study. All individuals underwent distance visual acuity (DVA) measurement with Snellen chart and Titmus vision screener V4, at 6 m on the same day. Later, these individuals underwent colour vision testing with Ishihara pseudo isochromatic plates and Titmus vision screener V4. Results: The age distribution ranged from 19 to 53 years with mean age as 26.6 years. Males (87.4%) were more as compared to females. Mean DVA measured by Snellen's chart and Titmus vision screener V4 were 0.088 ± 0.15 and 0.110 ± 0.17, respectively (p = 0.000). Mean difference between DVA by Snellen's chart and Titmus screener V4 was -0.021 ± 0.82 with 95% CI (-0.026 to -0.016). For measuring visual acuity, Titmus vision screener V4 showed a sensitivity of 99.5% and specificity of 90.6%. Negative predictive value and positive predictive value were 99.6% and 85.6%, respectively. For diagnosing colour perception, the Titmus vision screener V4 showed a sensitivity of 100% and specificity of 99.8%. The negative predictive value and positive predictive value were 100% and 88.8% respectively. Area under the curve of receiver operating characteristic (ROC) curve was 0.960 with 95%CI (0.949-0.972). Conclusion: Our study supports use of Titmus vision screener V4 as an excellent screening tool for measurement of visual acuity as well as colour perception.

Comparison of Snellen Visual Acuity Measurements in Retinal Clinical Practice to Electronic ETDRS Protocol Visual Acuity Assessment.

PURPOSE: Evaluate the differences between clinical visual acuity (VA) as recorded in medical records and electronic Early Treatment Diabetic Retinopathy Study (eETDRS) protocol VA measurements and factors affecting the size of the differences. DESIGN: Retrospective chart review. PARTICIPANTS: Study and fellow eyes of participants enrolled in DRCR Retina Network Protocols AC and AE (diabetic macular edema), and W (nonproliferative diabetic retinopathy) with clinical VA recorded within 3 months before the protocol visit. METHODS: Differences and their association with patient and ocular factors were evaluated using linear mixed models with random effects for correlations within sites and participants. MAIN OUTCOME MEASURE: Difference between VA letter scores measured by eETDRS during a study visit versus measured by Snellen during a regular clinical visit (Snellen fraction converted to eETDRS). RESULTS: Data from 1016 eyes (511 participants) across 74 sites were analyzed. The mean VA measurements were 68.6 letters (Snellen equivalent 20/50) at the clinical visit and 76.3 letters (Snellen equivalent 20/32) at the protocol visit, with a mean (standard deviation [SD]) of 26 (21) days between visits. Mean (SD) protocol VA was better than clinical VA by 7.6 (9.6) letters overall, 10.7 (12.6) letters in eyes with clinical VA ≤ 20/50 (n = 376), and 5.8 (6.6) letters in eyes with clinical VA ≥ 20/40 (n = 640). On average, the difference between clinical and protocol VA was 1.3 letters smaller for every 1-line (5 letters) increase in clinical VA (P < 0.001). Mean (SD) differences by clinical correction of refractive error were 3.9 (9.0) letters with refraction, 6.9 (9.2) letters with glasses/contact lenses, 7.9 (11.5) letters with pinhole, and 9.8 (9.3) letters without correction (P = 0.06). CONCLUSIONS: On average, clinical Snellen VA is 1 to 2 lines worse than eETDRS protocol refraction and VA testing, which may partly explain why clinical practice does not always replicate clinical trial results. Eyes with lower clinical measurements and eyes tested without clinical refraction tended to have larger differences. Considering the potential discrepancies between clinical and protocol VA measurements, refracting eyes in the clinic may benefit patients when determining treatment plans and study referrals based on vision. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

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.

[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.

Comparison of visual acuity measurements via three different methods in preschool children: Lea symbols, crowded Lea symbols, Snellen E chart.

PURPOSE: The aim of this study was to compare three different methods to measure visual acuity (VA) in healthy and amblyopic preschool children: a Snellen E chart (SE), a single Lea symbols (SLS), and a crowded Lea symbols (CLS). METHODS: Seventy-eight eyes of 54 patients (28 females, 26 males) were included in this cross-sectional, comparative study. The control group consisted of 30 healthy cases, and the amblyopic group consisted of 24 patients with amblyopia. Best-corrected VA (BCVA) measurements with SLS, CLS, and SE were compared in control eyes (CE), amblyopic eyes (AE), and fellow eyes (FE) separately. RESULTS: The mean age of the cohort was 5.7 ± 0.7 years (range 5-7 years). The mean refractive error was +1.02 ± 0.36 D (diopter, spherical equivalent) in CE, +5.59 ± 2.45 D in AE, and +3.96 ± 2.38 D in FE. The median BCVA (logMAR) was (in order of SLS, CLS, and SE) 0.00 [interquartile range (IQR) 0.10], 0.10 (IQR 0.10), 0.00 (IQR 0.10) in CE, 0.25 (IQR 0.33), 0.35 (IQR 0.30), 0.25 (IQR 0.38) in AE, and 0.10 (IQR 0.08), 0.10 (IQR 0.00), 0.10 (IQR 0.10) in FE. There was no statistically significant difference between the three methods in terms of the CE or FE (p > 0.05). In contrast, there was a statistically significant difference in AE (p < 0.05). The mean VA measurement with SLS was higher compared with CLS in AE. A positive and strong correlation between the three charts was found in all of the groups (p < 0.001). CONCLUSION: We found SLS, CLS, and SE to be consistent: all three methods can be used to obtain measurements of VA in healthy and amblyopic preschool children.

Correcting Finger Counting to Snellen Acuity.

In this paper, the authors describe an online tool with which to convert and thus quantify count finger measurements of visual acuity into Snellen equivalents. It is hoped that this tool allows for the re-interpretation of retrospectively collected data that provide visual acuity in terms of qualitative count finger measurements.

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.

Evaluation of Agreement Between Sweep Visual Evoked Potential Testing and Subjective Visual Acuity.

Objectives: The primary objective of this study was to evaluate the agreement of visual acuity (VA) obtained with the sweep visual evoked potential (sVEP) method with the VA obtained with the Snellen chart. The secondary objective was to examine the effect of age and gender on agreement. Materials and Methods: Best corrected VAs of subjects were recorded with the Snellen chart, and sVEP testing was performed according to the recommendations of the International Society for Clinical Electrophysiology of Vision (ISCEV). Snellen VAs and sVEP measurements were analyzed using logMAR conversion for statistical analysis. Agreement was evaluated with Bland-Altman analysis. Results: The study included 49 subjects with a mean age of 53.5±17.3 years (range: 19-75 years) and mean Snellen VA of 0.31±0.32 logMAR (range: 1.3-0.0 logMAR). In the Bland-Altman analysis, the mean differences between the VA and sVEP measurements (VA-sVEP) were significantly different and outside the limits of agreement (p=0.035). A significant proportional bias (p=0.0007) was found in the regression analysis performed between VA-sVEP and the mean VA. According to the Bland-Altman analysis of sex subgroups, there was a significant difference between VA and sVEP measurements in female subjects (p=0.006). The difference between VA and sVEP measurement increased significantly with older age (R2: 0.306, p<0.001, ß: 0.05 [0.03, 0.08]). Conclusion: In conclusion, sVEP measurements and VAs did not show statistical agreement. Cranial anatomy and endocrine differences of the subjects may affect their sVEP measurements. The difference between the methods varies according to VA level. Directly using sVEP results instead of VA would not be appropriate.

The Best Dentistry Professional Visual Acuity Measured under Simulated Clinical Conditions Provides Keplerian Magnification Loupe: A Cross-Sectional Study.

Visual acuity plays an important role in dentists' vision in their daily clinical routine. This study aimed to determine dental students' visual acuity without optical aids and when using magnification devices in simulated clinical conditions. The participants were forty-six students at the School of Dental Medicine with a visual acuity of 1.0 in decimal values or 100% in percentage. The central visual acuity was tested using a miniature Snellen eye chart placed in the molar cavity of a dental phantom, in simulated clinical conditions under five different settings (natural visual acuity, by applying head magnifying glasses x1,5 and binocular magnifying devices using Galileo's x2,5/350 mm, Keplerx3,3/450 mm and Keplerx4,5/350 mm optical system). The Wilcoxon Signed Rank test shows that the distribution of measurements of the visual acuity undertaken by the application of magnifying devices (VNL, VGA2,5, VKP3,3, VKP4,5) contained higher values of visual acuity than those received by the use of natural vision (VSC) (p < 0.001 for the comparison to the VNL, VGA2,5, VKP3,3 and VKP4,5 groups). The highest and statistically most significant increase in visual acuity is achieved using the Keplerian telescope x4.5/350 mm. The application of magnifying devices provided dentistry professionals with better visual acuity, improving detail detection in an oral cavity during dental procedures by magnifying the oral structure. The use of magnification devices means much more precise work, decreases the operating time, improves posture and reduces muscle pain in the shoulder during dental treatment.

Ease and Willingness to Use Smartphone Applications for Visual Acuity Assessment Among Patients in Ahmadu Bello University Teaching Hospital, Zaria.

Background: Smartphone applications (apps) are increasingly becoming more popular for medical use. Aim: The aim of this article is to determine the willingness and ease of using smartphone apps for visual assessment among adult patients attending the general outpatient ophthalmology clinic of Ahmadu Bello University Teaching Hospital, Zaria in Nigeria. Design: The study was a hospital-based descriptive cross-sectional design. Materials and Methods: New and old adult patients who presented at the clinic and consented to the study were selected. Visual acuity assessment was done using a 6-m Snellen chart and three selected Smartphone visual acuity applications sequentially. A semi-structured questionnaire was used for data collection and then analysed using SPSS version 23. Results: A total of 287 patients were studied. Majority (96%) of the patients found the Smartphone apps to be easy to use. A good proportion (76%) of the patients also believed that Smartphone charts were easier to use than the conventional Snellen chart and expressed willingness to use the app again. Conclusion: Smartphone visual acuity apps could offer a convenient, easy-to-learn, and easy-to-use means of visual acuity assessment. This coupled with the demonstrated patient's willingness to embrace this technology could be used to encourage the use of clinically validated apps for the early detection as well as monitoring of any impairment of vision, especially in out-of-clinic situations.

[New DIN and ISO norms for determination of visual acuity]. / Neue DIN- und ISO-Normen zur Sehschärfebestimmung.

Recently, three international norms (ISO) for visual acuity assessment were revised. The DIN EN ISO 8596:2018 stipulates the Landolt C eye chart as the standard optotype and specifies display characteristics. An informative annex lists clinical optotypes for the first time. These include the ETDRS chart, Snellen chart and pediatric optotypes; however, these clinical optotypes do not have the same status as the Landolt C chart, since even with identical font size and stroke width they may differ in recognizability. The technical report ISO/TR 19498:2015 complements DIN EN ISO 8596. A scientifically appropriate procedure is described, which enables a quantitative correlation of clinical optotypes with the Landolt C chart. The DIN EN ISO 10938:2016 describes the required optical quality of optotypes. For the first time, electronic devices are explicitly approved for standardized visual acuity tests. Consequently, according to this amendment electronic devices may be used for acuity assessment for ophthalmological expert opinions according to DIN 58220, part 3.

A Comparison of different scoring terminations rules for visual acuity testing: from a computer simulation to a clinical study.

Purpose: To compare four visual acuity (VA) scoring termination rules. Methods: A computer simulation generated 30,000 virtual patients who underwent 10 repetitions for each of four termination rules, on both the Snellen and ETDRS charts (2.4 million tests performed in total). Three termination rules focused on the smallest character row: all characters were correctly identified (100%), one character was incorrectly identified (one miss) and 50% or more of the characters were correctly identified (50%). The forth termination rule used a calculation in which each character, when correctly recognized, contributed a proportional increment (per-letter). Accuracy, test-retest variability (TRV) and test duration were measured. Next, a clinical study was conducted in which 254 subjects underwent three repetitions of the ETDRS VA test from 4 m, and VA scores for each of the four scoring termination rules were calculated. Results: In the Snellen simulation, the mean accuracy of the 100%, one miss, 50% and per-letter termination rules in decimal was 0.23 (-0.16 logMAR), 0.11 (-0.09 logMAR), 0.10 (-0.08 logMAR), and -0.08 (0.08 logMAR) respectively; while with the ETDRS simulation, the mean accuracy in decimal was 0.34 (-0.22 logMAR), 0.14 (-0.11 logMAR), 0.07 (-0.06 logMAR), and 0.07 (-0.05 logMAR), respectively. For the ETDRS simulation, the per-letter had the lowest TRV values and the longest test duration. In the clinical study (n = 254), the reproducibility of the 100%, one miss, 50% and per-letter was 0.50, 0.53, 0.17, 0.14, respectively. Conclusions: Clinical study and simulation data both suggest that the 100% and one-miss termination rules have higher TRVs, while the 50% and per-letter demonstrated much tighter, and rather close, TRV values.

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.

Morphological characterization and distribution of antennal sensilla of Diaphania angustalis Snellen (Lepidoptera: Crambidae).

Diaphania angustalis Snellen (Lepidoptera: Crambidae) is the main defoliator of Alstonia schalaris. In this article, observation of external morphological and ultrastructure structure of adult antennae of D. angustalis was carried out using the scanning and transmission electron microscope. The results showed that both male and female antennae were filiform and could be divided into scape, pedicel, and flagellum. There are eight types and two subtypes of antennal sensilla, namely, sensilla trichodea, sensilla chaetica (I & II), sensilla coeloconica, sensilla auricillica, sensilla styloconica, sensilla squamiformia, capitate peg, and Böhm bristles. Most sensilla are concentrated in venter and the sides of antennae. Analyses on morphological and quantitative differences of antennal sensilla between male and female adults. The size of SCo is significantly different between male and female. In terms of quantity, only SSt and CP have no significant differences between male and female. By comparing the existing antennal sensilla of Crambidae, it is found that STr, SCh, SCo, and SAu are common sensilla. These results can contribute to further research on the function of sensilla of D. angustalis relating to its behavior. A detailed description is provided of the antennal sensilla in Diaphania angustalis. Diaphania angustalis has the rare sensilla of capitate peg in Crambidae. No sexual dimorphism of sensillum types is found in the species. The number and distribution of sensilla trichodea, sensilla chaetica, sensilla coeloconica, and sensilla auricillica sensillum are different.

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.

Comparison of Snellen and Early Treatment Diabetic Retinopathy Study charts using a computer simulation.

AIM: To compare accuracy, reproducibility and test duration for the Snellen and the Early Treatment Diabetic Retinopathy Study (ETDRS) charts, two main tools used to measure visual acuity (VA). METHODS: A computer simulation was programmed to run multiple virtual patients, each with a unique set of assigned parameters, including VA, false-positive and false-negative error values. For each virtual patient, assigned VA was randomly chosen along a continuous scale spanning the range between 1.0 to 0.0 logMAR units (equivalent to 20/200 to 20/20). Each of 30 000 virtual patients were run ten times on each of the two VA charts. RESULTS: Average test duration (expressed as the total number of characters presented during the test ±SD) was 12.6±11.1 and 31.2±14.7 characters, for the Snellen and ETDRS, respectively. Accuracy, defined as the absolute difference (± SD) between the assigned VA and the measured VA, expressed in logMAR units, was superior in the ETDRS charts: 0.12±0.14 and 0.08±0.08, for the Snellen and ETDRS charts, respectively. Reproducibility, expressed as test-retest variability, was superior in the ETDRS charts: 0.23±0.17 and 0.11±0.09 logMAR units, for the Snellen and ETDRS charts, respectively. CONCLUSION: A comparison of true (assigned) VA to measured VA, demonstrated, on average, better accuracy and reproducibility of the ETDRS chart, but at the penalty of significantly longer test duration. These differences were most pronounced in the low VA range. The reproducibility using a simulation approach is in line with reproducibility values found in several clinical studies.

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.

Design of customizable automated low cost eye testing system.

BACKGROUND AND OBJECTIVES: In many underdeveloped and third world countries, eye care is often neglected due to illiteracy. Particularly people in rural areas suffer with eye problems due to mal nutrition. The government is spending lot of money and efforts in screening the people at periodic intervals. One of the challenges faced by the doctors is screening the school children. MATERIALS AND METHODS: The standard Snellen letter chart based diagnostic system does not work always. There are instances where the first few students who undergo this diagnostic system, memorize the letter sequence of the Snellen letter chart and convey the same to other fellow students. Hence other students simply read out the Snellen letter sequence from their memory, not by looking at the Snellen letter chart. Thus there is a need of randomizing the sequence of letters being displayed on the Snellen letter chart for every student to be diagnosed for eye testing. CONCLUSION: In the present paper we are proposing a customizable, software based, cost effective solution which involves a standard personal computer (PC) fitted with a camera, headphone and speaker system. The envisaged system can be administered even by the trained persons. The proposed system is also suitable for remote diagnosis of patients, particularly in the field of telemedicine.