Visual Acuity Testing: Feedback Affects Neither Outcome nor Reproducibility, but Leaves Participants Happier

Scotopic and Photopic Conventional Visual Acuity and Hyperacuity - Binocular Summation

Purpose

The purpose of this study was to determine and compare binocular summation (BiS) of conventional visual acuity (cVA) versus hyperacuity (hVA) for photopic and scotopic luminance conditions as a potential biomarker to assess the outcome of interventions on binocular function.

Methods

Sixteen young adults (age range [years] = 21-31; 8 women; cVA logMAR < 0.0) participated in this study. The Freiburg Visual Acuity Test (FrACT) was used for VA testing and retested on another day. Both cVA and hVA were determined for dark grey optotypes on light grey background. Participants underwent 40 minutes of dark adaptation prior to scotopic VA testing. Binocular and monocular VA testing was performed. The eye with better VA over the 2 days of testing was selected, the BiS was quantified (binocular VA - better monocular VA) and repeated measures ANOVAs were performed.

Results

Binocular VA exceeded monocular VA for all luminance conditions, VA-types, and sessions. We report BiS estimates for photopic and scotopic cVA and hVA, (logMAR BiS ± SEM [decimal BiS]): photopic = -0.01 ± 0.01 [1.03] and -0.06 ± 0.03 [1.15]; and scotopic = -0.05 ± 0.01 [1.12] and -0.11 ± 0.04 [1.28], respectively). Improvement for binocular vision estimates ranged from 0.01 to 0.11 logMAR. A repeated-measures ANOVA (RM ANOVA) did not reveal significant effects of LUMINANCE or VA TYPE on BiS, albeit a trend for strongest BiS for scotopic hVA (15% vs. 28%, photopic versus scotopic, respectively) and weakest for photopic cVA (3% vs. 12%, photopic versus scotopic conditions, respectively).

Conclusions

Our results indicate that BiS of VA is relevant to scotopic and photopic hVA and cVA. It appears therefore a plausible candidate biomarker to assess the outcome of retinal therapies restoring rod or cone function on binocular vision.

Translational Relevance

Binocular summation of visual acuity might serve as a clinical biomarker to monitor therapy outcome on binocular rod and cone-mediated vision.

The Freiburg Acuity Test in Preschool Children: Testability, Test-Retest Variability, and Comparison With LEA Symbols

Purpose

To determine the testability, performance, and test-retest variability (TRV) of visual acuity (VA) assessment using the Freiburg Visual Acuity Test (FrACT) compared to the LEA Symbols Test (LEA) in preschool children.

Methods

In 134 preschool children aged 3.0 to 6.8 years, monocular VA of each eye was measured twice with a four-orientation Landolt C version of the FrACT and once with the LEA. FrACT runs were preceded by a binocular run for explanatory purposes. Test order alternated between subjects. Optotypes were presented on a computer monitor (FrACT) or on cards (LEA) at a distance of 3 m.

Results

Overall, 68% completed the FrACT (91/134 children) and 88% completed the LEA (118/134 children). Testability depended on age: FrACT, 19% (<4 years) and 87% (≥4 years); LEA, 70% (<4 years) and 95% (≥4 years). Mean ± SD VA difference between tests was 0.11 ± 0.19 logarithm of the minimum angle of resolution [logMAR], with LEA reporting better acuity. The difference depended on age (0.27 ± 0.23 logMAR [<4 years], 0.09 ± 0.18 logMAR [≥4 years], P < 0.001) and on test sequence (higher age dependence of FrACT VAs for LEA first, P < 0.001). The 95% limits of agreement for the FrACT TRV were ±0.298 logMAR.

Conclusions

The examiner-independent FrACT, using international reference Landolt C optotypes, can be used to assess VA in preschool children aged ≥4 years, with reliability comparable to other pediatric VA tests.

Translational Relevance

Use of the automated FrACT for VA assessment in preschool children may benefit objectivity and validity as it is a computerized test and employs the international reference Landolt C optotype.

The Impact of Different Color Temperatures and Sources of Light on Mood and Vision: Acuity and Color Recognition

Background: Light is a physical factor that can influence the mood and vision of people during work and study. According to the importance of these physical factors, the present study aimed to investigate the effect of the source and color temperature on the mood and vision (acuity and color recognition) of students of TUMS and USWR medical universities. Methods: The present study is an applied study, and the research method is quasi-experimental. Twenty subjects were determined by first-type error (0.05) and test power (0.08). The mood was measured using the profile of mood states (POMS), visual acuity in different lighting conditions based on Snellen and FrACT methods, and color recognition by Ishihara’s test. Data were analyzed by SPSS 22, one-way ANOVA, and Greenhouse-Geisser. Results: The results of investigating six subscales of the POMS scale in sunlight, LED, and fluorescent with color temperatures of 4000 K and 3000 K indicated improvement in mood states (P < 0.001). Color recognition under different lighting conditions showed no significant difference (P < 0.05). However, visual acuity with the FrACT method under sunlight showed a significant difference in other lighting conditions (P < 0.001). Conclusions: Light sources can influence mood and vision states (acuity and color recognition) under different lighting conditions. Therefore, using sunlight in educational environments can improve the mood and state of students.

Quantification of the Dynamic Visual Acuity Space at Real-World Luminances and Contrasts: The VA-CAL Test

Purpose

Best-corrected visual acuity (BCVA) is assessed at a single standardized luminance with maximum optotype contrast, not reflecting the constantly changing daily-life viewing conditions. For a more realistic estimation of visual performance at varying object contrasts (Cs) and ambient luminances (ALs), we developed a new VA test, VA-CAL.

Methods

Landolt-C-rings between 18% and 95% Weber contrast, were presented at 1 m distance (8 Alternative Forced Choice) on a 5.7 degree field in the middle of a frosted glass screen (66 degrees), back-lit by 3060 LEDs (generating ambient luminances between 0-10,000 cd/m²). Visual acuity (VA) was measured in 14 normally sighted participants twice for 8 conditions of ambient luminance and 6 conditions of contrast using a QUEST staircase procedure.

Results

VA improved continuously up to an ambient luminance of 3000 to 5000 cd/m² (best mean VA ± SEM: -0.47 ± 0.03 logMAR at C = 95%, AL = 3000 cd/m²), followed by a decline of VA at higher luminances with good test-retest variability. As expected, reduced contrast leads to a lower VA (worst mean VA ± SEM: -0.03 ± 0.03 logMAR at C = 18%, AL = 0 cd/m²). A 3D plot of these data shows the VA space (VAS) extending between the contrast and luminance axes, which describes the dynamics of VA continuously changing under varying everyday life conditions.

Conclusions

VA-CAL, an automated device and procedure, allows for simultaneous evaluation of VA at various contrast-luminance combinations, thus providing a more comprehensive assessment of spatial vision problems not seen with standard BCVA tests.

Translational Relevance

The new BCVA test VA-CAL incorporates a range of everyday contrast and ambient luminance conditions for a more realistic description of visual performance.

Implications of a Remote Study of Children With Cerebral Visual Impairment for Conducting Virtual Pediatric Eye Care Research: Virtual Assessment Is Possible for Children With CVI

The Pandemic of 2020 impacted conducting in-person research. Our proposed project already had an asynchronous online component but was later morphed to add a synchronous online component, thereby eliminating the need for in-person assessment. The project compares the results of various tests between a group of children with Cerebral Visual Impairments (CVI) (N = 4) and an age-matched sample of children without CVI (N = 3) from a pediatric low vision clinic. This model was trialed with a small convenient sample of typically developing children in the same age range (N = 4). Given the positive feedback, recruitment for the larger study was done via encrypted e-mail rather than through traditional mailing. The asynchronous components included recruitment, pre-assessment information, the Flemish CVI questionnaire, Vineland-3 comprehensive parent questionnaire for assessment of age equivalent, and vision function tests, such as contrast sensitivity. The synchronous components were administered via Zoom telehealth provided by necoeyecare.org and included assessment of visual acuity via the Freiburg Visual Acuity and Contrast Test (FrACT) electronic software and assessment of visual perceptual batteries via the Children’s Visual Impairment Test for developmental ages 3–6-years (CVIT 3–6). Our virtual testing protocol was successful in the seven participants tested. This paper reviews and critiques the model that we utilized and discusses ways in which this model can be improved. Aside from public health considerations during the pandemic, this approach is more convenient for many families. In a broader perspective, this approach can be scaled for larger N studies of rare conditions, such as CVI without being confined by proximity to the researcher.

Influence of Lenslet Configuration on Short-Term Visual Performance in Myopia Control Spectacle Lenses

Purpose: This study aimed to evaluate short-term visual performance and optical quality of three different lenslet configurations on myopia control spectacle lenses.

Materials and Methods: This study utilized a cross-over design. Distance visual acuity (VA) was measured in 50 myopic children; contrast sensitivity (CS) was measured in 36 myopic children. For each test, four spectacle lenses were evaluated in a random order: single-vision lens (SVL), lens with concentric rings of highly aspherical lenslets (HAL), lens with concentric rings of slightly aspherical lenslets (SAL), and lens with honeycomb configuration of spherical lenslets (HC). The modulation transfer function (MTF) and MTF area (MTFa) were used to determine optical quality. All tests were performed monocularly on the right eye with full correction.

Results: HAL and SAL had larger MTFa than HC. VA in lenses with lenslets was significantly reduced compared to SVL (all p < 0.01). The reduction in VA was worse with HC than with SAL (p = 0.02) and HAL (p = 0.03); no effect of lenslet asphericity was found (p > 0.05). VA changes induced by lenslets showed no correlation with spherical equivalent refraction (all p > 0.05) and were weakly positively associated with age for SAL (r = 0.36, p = 0.01) and HC (r = 0.31, p = 0.03), but not for HAL (p = 0.30). The area under the log contrast sensitivity function (AULCSF) decreased with HAL and HC (all p < 0.001) in all illumination levels, and AULCSF with HAL was higher than that with HC in a photopic condition (1.17 ± 0.10 vs. 1.10 ± 0.13, p = 0.0004). The presence of lenslets did not affect CS at 3 cycles per degree (cpd) (p = 0.80). At 6 to 18 cpd, CS was significantly reduced by HAL and HC (all p < 0.05), but not SAL (p > 0.05) compared to SVL. At high spatial frequencies (>12 cpd) both SAL and HAL reduced CS significantly less than HC (all p < 0.01).

Conclusion: Short-term visual performance was minimally impaired by looking through the lenslet structure of myopia control spectacle lenses. Concentric rings with aspherical lenslets had a significantly lower impact on both VA and CS than honeycomb configuration with spherical lenslets.

Fundus-controlled perimetry (microperimetry): Application as outcome measure in clinical trials

Fundus-controlled perimetry (FCP, also called 'microperimetry') allows for spatially-resolved mapping of visual sensitivity and measurement of fixation stability, both in clinical practice as well as research. The accurate spatial characterization of visual function enabled by FCP can provide insightful information about disease severity and progression not reflected by best-corrected visual acuity in a large range of disorders. This is especially important for monitoring of retinal diseases that initially spare the central retina in earlier disease stages. Improved intra- and inter-session retest-variability through fundus-tracking and precise point-wise follow-up examinations even in patients with unstable fixation represent key advantages of these technique. The design of disease-specific test patterns and protocols reduces the burden of extensive and time-consuming FCP testing, permitting a more meaningful and focused application. Recent developments also allow for photoreceptor-specific testing through implementation of dark-adapted chromatic and photopic testing. A detailed understanding of the variety of available devices and test settings is a key prerequisite for the design and optimization of FCP protocols in future natural history studies and clinical trials. Accordingly, this review describes the theoretical and technical background of FCP, its prior application in clinical and research settings, data that qualify the application of FCP as an outcome measure in clinical trials as well as ongoing and future developments.

Effects of Nicotine Gum Administration on Vision (ENIGMA-Vis): Study Protocol of a Double-Blind, Randomized, and Controlled Clinical Trial

Studies reported that tobacco addiction was related to visual impairments, but one unresolved issue is whether the impairments are related to the many compounds existing in the cigarettes or to the effects of nicotine. On the other hand, nicotine gum can be used as replacement therapy or as a neuroprotective agent for some diseases. The main purpose of this controlled trial is to investigate the effects of nicotine gum on vision. The ENIGMA-Vis trial aims to compare two dosages of nicotine gum (2 and 4 mg) and a placebo gum in a randomized, double-blind, placebo-controlled trial of 100 participants to be allocated into a single group assignment of repeated measures (two studies; N = 50 for each one). Eligibility criteria are healthy non-smokers not diagnosed with substance abuse and without an acute or chronic medical condition. Intervention will last three sessions for each participant with a window frame of 1 week per session. Study outcomes are (1) short-term effects of nicotine gum on contrast sensitivity; (2) short-term effects of nicotine gum on chromatic contrast discrimination; and (3) whether demographics, body mass index, or serum cotinine predicts response of visual processing. This study addresses an important gap in the effects of nicotine on vision. One of the main takeaways of this study is to understand the effects of nicotine on contrast sensitivity and chromatic contrast discrimination. This information will provide a further understanding of how nicotine interacts with early visual processes and help determine how the different components present during smoking can affect vision.

Clinical Trial Registration Number: RBR-46tjy3.

Specificity and retention of visual perceptual learning in young children with low vision

There is evidence that a pen-and-paper training based on perceptual learning principles improves near visual acuity in young children with visual impairment. The aim of the present study is to measure specificity and retention of its training effects during one year. Sixteen visually impaired children aged 4-8 years were divided in two age- and acuity-matched groups: an early (n = 9) and late treatment group (n = 7). Training consisted of 12 sessions (2× per week for 6 weeks). Studied variables were uncrowded and crowded binocular near visual acuity (40 cm), distance visual acuity (3.0 m) and fine motor skills (Beery VMI, subtest Motor Control). In the early treatment group, we measured at 0 months (pre-training), at 2 months (post-training), at 8 months (6 months post-training) and at 14 months (12 months post-training) since inclusion. In the late treatment group, three pre-training measurements were performed at 0, 2 and 8 months, and two measurements at 0 and 6 months post-training. In the short term, training improved uncrowded and crowded near visual acuity at 0.4 m by 0.13 ± 0.03 and 0.09 ± 0.03 logMAR, respectively (mean ± SEM). Training did not affect distance acuities or Beery scores. Learning effects on uncrowded and crowded near visual acuities remained intact 6-12 months after training. We conclude that the pen-and-paper training specifically improves near visual acuities but does not transfer to distance acuities or fine motor skills. Improvements in near visual acuity are retained over time, bolstering its clinical value.

Vitreous and Vision Degrading Myodesopsia

Macromolecules comprise only 2% of vitreous, yet are responsible for its gel state, transparency, and physiologic function(s) within the eye. Myopia and aging alter collagen and hyaluronan association causing concurrent gel liquefaction and fibrous degeneration. The resulting vitreous opacities and collapse of the vitreous body during posterior vitreous detachment are the most common causes for the visual phenomenon of vitreous floaters. Previously considered innocuous, the vitreous opacities that cause floaters sometimes impact vision by profoundly degrading contrast sensitivity function and impairing quality-of-life. While many people adapt to vitreous floaters, clinically significant cases can be diagnosed with Vision Degrading Myodesopsia based upon echographic assessment of vitreous structure and by measuring contrast sensitivity function. Perhaps due to the ubiquity of floaters, the medical profession has to date largely ignored the plight of those with Vision Degrading Myodesopsia. Improved diagnostics will enable better disease staging and more accurate identification of severe cases that merit therapy. YAG laser treatments may occasionally be slightly effective, but vitrectomy is currently the definitive cure. Future developments will usher in more informative diagnostic approaches as well as safer and more effective therapeutic strategies. Improved laser treatments, new pharmacotherapies, and possibly non-invasive optical corrections are exciting new approaches to pursue. Ultimately, enhanced understanding of the underlying pathogenesis of Vision Degrading Myodesopsia should result in prevention, the ultimate goal of modern Medicine.

Determination of scotopic and photopic conventional visual acuity and hyperacuity

PURPOSE

Visual acuity (VA) is an important determinant of visual function. Here we establish procedures and recommendations for VA testing extending beyond the classical VA and thus make them available for future studies of visual function in health and disease. Specifically, we provide reference values for photopic and scotopic conventional uncrowded visual acuity (cVA) and Vernier-hyperacuity (hVA) and assess their reproducibility and dependence on contrast polarity.

METHODS

For ten observers with normal vision, we determined photopic ("p"; maximal luminance 220 cd/m²) and scotopic ("s"; maximal luminance 0.004 cd/m²; 40 min of dark adaptation) cVA and hVA, for two contrast polarities i.e. black optotypes on white background and vice versa. To assess intersession effects, two sets of measurements were obtained on different days.

RESULTS

Compared to pcVA (1.32 decimal VA; - 0.12 ± 0.02 LogMAR), the phVA (14.45 decimal VA; - 1.16 ± 0.04 LogMAR) scaled (in terms of decimal visual acuity) on average with a factor 11.0, the scVA (0.12 decimal VA; 0.91 ± 0.03 LogMAR) with a factor of 0.1, and the shVA (1.47 decimal VA; - 0.17 ± 0.02 LogMAR) with a factor of 1.1. There were neither significant effects of contrast polarity (p > 0.12), nor of session (p > 0.28).

CONCLUSIONS

Our approach optimises integrated photopic and scotopic cVA and hVA measurements for general use and thus encourages the integration of these important measures of scotopic visual function in future studies. The absence of strong intersession effects demonstrates that no dedicated training session is needed to obtain scotopic and hVA measurements. The combined measures of scotopic and photopic VAs open a field of applications to study interplay and plasticity of the retinal photoreceptor systems and cortical processing in health and visual disease. As a rule of thumb, hyperacuity is 10× higher both in the photopic and scotopic range than conventional acuity. Thus, scotopic hyperacuity is close to photopic conventional acuity.

Evaluation of the “Freiburg Acuity VEP” on Commercial Equipment

Purpose

To assess the implementation and outcome quality of the Freiburg Acuity VEP methodology (Bach et al. in Br J Ophthalmol 92:396–403, 2008) on the Diagnosys Espion Profile and E3 electrophysiology systems.

Methods

We recorded visual evoked potentials (VEPs) from both eyes of 24 participants, where visual acuity (VA) was either full or reduced with scatter foils to approximately 0.5 and 0.8 LogMAR, resulting in a total of 144 recordings. Behavioral VA was measured in each case under the same conditions using the Freiburg Acuity Test (FrACT); VEP-based acuity was assessed with the “heuristic algorithm,” which automatically selects points for regression to zero amplitude.

Results

Behavioral VA ranged from − 0.2 to 1.0 LogMAR. The fully automatic heuristic VEP algorithm resulted in 8 of 144 recordings (6%) that were scored as “no result.” The other 136 recordings (94%) had an outcome of − 0.20 to 1.3 LogMAR (which corresponds to a range of 20/12.5–20/400, or 6/3.8–6/120, in Snellen ratios; or 1.6–0.1 in decimal acuity). The heuristic VEP algorithm agreed with the behavioral VA to within ± 0.31 LogMAR (95% limits of agreement), which is equivalent to approximately three lines on a VA chart.

Conclusions

The successful implementation of the Freiburg Acuity VEP “heuristic algorithm” on a commercial system makes this capability available to a wider group of users. The limits of agreement of ± 0.31 LogMAR are close to the original implementation at the University of Freiburg and we believe are clinically acceptable for a fully automatic, largely objective assessment of visual acuity.

TuebingenCSTest - a useful method to assess the contrast sensitivity function

Since contrast sensitivity (CS) relies on the accuracy of stimulus presentation, the reliability of the psychophysical procedure and observer's attention, the measurement of the CS-function is critical and therefore, a useful threshold contrast measurement was developed. The Tuebingen Contrast Sensitivity Test (TueCST) includes an adaptive staircase procedure and a 16-bit gray-level resolution. In order to validate the CS measurements with the TueCST, measurements were compared with existing tests by inter-test repeatability, test-retest reliability and time. The novel design enables an accurate presentation of the spatial frequency and higher precision, inter-test repeatability and test-retest reliability compared to other existing tests.