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Eye and Vision (London, England) Aug 2022To evaluate microscopically whether the print quality and accuracy of sizing of Landolt ring near vision charts are adequate for the calibration of reading charts.
PURPOSE
To evaluate microscopically whether the print quality and accuracy of sizing of Landolt ring near vision charts are adequate for the calibration of reading charts.
METHODS
Near vision charts with Landolt rings from Oculus GmbH (C-Test; Wetzlar, Germany), Precision Vision (Woodstock, IL) and the RADNER Charts were examined, as well as custom-made Landolt rings optimized for print quality. Microscopic investigations and measurements were performed by using a Huvitz HSZ 600 stereomicroscope (Nikon NIS Elements software) to evaluate the height of the Landolt rings, the thickness of the lines, and the width of the openings. The deviations from the mathematically correct values, which were calculated as given in the EN/ISO 8596 and by the International Council of Ophthalmology (ICO), were analyzed (calculated for a test distance of 40 cm).
RESULTS
All the near vision charts showed notable deficiencies in print quality and aberrations from the nominal values in the height, thickness of the lines, and width of the openings. The openings were too narrow, whereas the height and thickness of the lines were larger than the nominal values. Even the openings of Landolt rings optimized for print quality were not always within an acceptable 5% tolerance and need further improvement.
CONCLUSION
This study reports inaccuracies in the heights, thicknesses of the lines, and widths of the openings of Landolt rings in all the near vision charts investigated. The extent of these inaccuracies excludes such near vision charts as reference tests for the calibration of reading charts. The x-height in relation to the visual angle still seems to be the most reliable method for standardizing the print sizes for reading charts.
PubMed: 35965343
DOI: 10.1186/s40662-022-00302-5 -
Attention, Perception & Psychophysics Nov 2019A previous study from our lab demonstrated retention of high tactile acuity throughout the lifespan in blind subjects in contrast to the typical decline found for...
A previous study from our lab demonstrated retention of high tactile acuity throughout the lifespan in blind subjects in contrast to the typical decline found for sighted subjects (Legge, Madison, Vaughn, Cheong & Miller, Percept Psychophys, 70 (8), 1471-1488, 2008). We hypothesize that preserved tactile acuity in old age is due to lifelong experience with focused attention to touch and not to blindness per se. Proficient pianists devote attention to touch - fingerings and dynamics - over years of practice. To test our hypothesis, we measured tactile acuity in groups of ten young (mean age 24.5 years) and 11 old (mean age 64.7 years) normally sighted pianists and compared their results to the blind and sighted subjects in our 2008 study. The pianists, like the subjects in 2008, were tested on two tactile-acuity charts requiring active touch, one composed of embossed Landolt rings and the other composed of dot patterns similar to braille. For both tests, the pianists performed more like the blind subjects than the sighted subjects from our 2008 study. For the ring chart, there was no significant difference in tactile acuity between the young and old pianists and no significant difference between the pianists and the blind subjects. For the dot chart, the pianists showed an age-related decline in tactile acuity, but not as severe as the sighted subjects from 2008. Our results are consistent with the hypothesis that lifelong experience with focused attention to touch acts to preserve tactile acuity into old age for both blind and sighted subjects.
Topics: Adult; Age Factors; Aged; Aging; Attention; Blindness; Female; Humans; Male; Middle Aged; Music; Occupational Diseases; Touch; Touch Perception; Vision, Ocular; Young Adult
PubMed: 31410761
DOI: 10.3758/s13414-019-01844-y -
Children (Basel, Switzerland) Mar 2024The purpose of this study was to develop a new pediatric acuity chart that can assess the minimum separation threshold by incorporating the minimum separation threshold...
The purpose of this study was to develop a new pediatric acuity chart that can assess the minimum separation threshold by incorporating the minimum separation threshold into the picture. To overcome the design limitations of the Landolt ring, two designs of highly versatile minimum separable thresholds that can be easily incorporated into a picture were created: a black, filled circle (the "Circle") and a segment (the "Square"), both with the same break as in the Landolt ring. The three designs-the Landolt ring, Circle, and Square-were used to evaluate and compare the differences in the visual acuity of 21 healthy adults. No significant differences were observed between the results of the visual acuity tested with the Landolt ring, Circle, and Square (Landolt ring vs. Circle: = 0.92, Landolt ring vs. Square: = 0.31, Circle vs. Square: = 0.40). The Bland-Altman analysis revealed no fixed errors between the Landolt ring and Circle and between the Landolt ring and Square (95% CI: -0.09-0.08, -0.09-0.12). Proportional errors were also not observed ( = 0.68, = 0.41). The Landolt ring, Circle, and Square designs obtained equal results in visual acuity, thus achieving the successful development of a novel pediatric visual acuity chart using these designs.
PubMed: 38671614
DOI: 10.3390/children11040397 -
Scientific Reports Nov 2023Dynamic visual acuity (DVA) is crucial for the perception of moving objects. While traditional DVA assessment tools predominantly focus on horizontal movements, the...
Dynamic visual acuity (DVA) is crucial for the perception of moving objects. While traditional DVA assessment tools predominantly focus on horizontal movements, the evaluation of vertical DVA remains unstandardized. Consequently, the disparities between vertical and horizontal DVAs are yet to be thoroughly investigated. Therefore, we designed a system capable of conducting multidirectional DVA tests and eye movement measurements. During the experiments, the participants identified the gap direction of the Landolt-C ring moving either horizontally or vertically. The speed of movement decelerated from its maximum as a high-speed infrared camera captured the pupil movements of the left eye at 500 fps. We conducted tests on 15 healthy university students (aged [Formula: see text] years) and measured vertical and horizontal DVAs five times each. DVA was deduced from the Landolt-C ring speed with accurate gap direction responses, and eye movement was assessed based on the total gaze movement distance. The results revealed superior DVA and eye movement in the horizontal direction compared with the vertical direction ([Formula: see text]). This highlights the anisotropic characteristics of DVA and eye movement. The proposed system has the potential for multidirectional dynamic vision evaluation and training in clinical scenarios.
Topics: Humans; Aged; Visual Acuity; Eye Movements; Movement; Vision Tests; Eye Movement Measurements
PubMed: 38017190
DOI: 10.1038/s41598-023-48292-1 -
Frontiers in Aging Neuroscience 2023Patients with Alzheimer's disease (AD) are known to exhibit visuospatial processing impairment, as reflected in eye movements from the early stages of the disease. We...
BACKGROUND
Patients with Alzheimer's disease (AD) are known to exhibit visuospatial processing impairment, as reflected in eye movements from the early stages of the disease. We investigated whether the pattern of gaze exploration during visual tasks could be useful for detecting cognitive decline at the earliest stage.
METHODS
Sixteen AD patients (age: 79.1 ± 7.9 years, Mini Mental State Examination [MMSE] score: 17.7 ± 5.3, mean ± standard deviation) and 16 control subjects (age: 79.4 ± 4.6, MMSE score: 26.9 ± 2.4) participated. In the visual memory task, subjects memorized presented line drawings for later recall. In the visual search tasks, they searched for a target Landolt ring of specific orientation (serial search task) or color (pop-out task) embedded among arrays of distractors. Using video-oculography, saccade parameters, patterns of gaze exploration, and pupil size change during task performance were recorded and compared between AD and control subjects.
RESULTS
In the visual memory task, the number of informative regions of interest (ROIs) fixated was significantly reduced in AD patients compared to control subjects. In the visual search task, AD patients took a significantly longer time and more saccades to detect the target in the serial but not in pop-out search. In both tasks, there was no significant difference in the saccade frequency and amplitude between groups. On-task pupil modulation during the serial search task was decreased in AD. The number of ROIs fixated in the visual memory task and search time and saccade numbers in the serial search task differentiated both groups of subjects with high sensitivity, whereas saccade parameters of pupil size modulation were effective in confirming normal cognition from cognitive decline with high specificity.
DISCUSSION
Reduced fixation on informative ROIs reflected impaired attentional allocation. Increased search time and saccade numbers in the visual search task indicated inefficient visual processing. Decreased on-task pupil size during visual search suggested decreased pupil modulation with cognitive load in AD patients, reflecting impaired function of the locus coeruleus. When patients perform the combination of these tasks to visualize multiple aspects of visuospatial processing, cognitive decline can be detected at an early stage with high sensitivity and specificity and its progression be evaluated.
PubMed: 37025964
DOI: 10.3389/fnagi.2023.1123456