-
Clinical & Experimental Optometry Sep 2021: Refracting low vision patients require special procedures and strategies. A device-taking the reduced visual acuity and higher blur tolerance into account-is designed...
: Refracting low vision patients require special procedures and strategies. A device-taking the reduced visual acuity and higher blur tolerance into account-is designed to measure refraction in this group.: Instant Vision Assessment Device (IVAD) is a stenopaeic slit refraction system in a binocular telescopic optometer calibrated to measure refraction. This study aims to validate IVAD in measuring refraction of low vision patients.: Refractions were measured with IVAD on the right eyes of 35 normal subjects (ages nine to 69) and on the better eyes of 20 low vision subjects (ages 60 to 90) and compared with subjective refraction (SR). The visual acuities were compared in the low vision group. Paired Student t-test and Bland-Altman analysis were used to test the significance of difference and limits of agreement between methods, respectively.: In normal subjects, mean spherical equivalent refraction (M) measured by IVAD and SR was -2.88 ± 2.51 D and -2.72 ± 2.29 D, respectively, and the difference of -0.16 ± 0.47 D was not statistically significant (p = 0.05, t = 2.03). In low vision subjects, M measured by IVAD and SR was-0.66 ± 2.64 D and -0.55 ± 2.61 D, respectively, and the difference of -0.11 ± 0.59 D was also not statistically significant (p = 0.43, t = 2.09). Only the astigmatism J0 in the normal subject group of -0.03 ± 0.24 D by IVAD and 0.07 ± 0.17 D by SR showed a statistically significant difference of -0.10 ± 0.25 D (p = 0.04, t = 2.03). In low vision subjects, mean visual acuities with refraction from IVAD and SR were 0.52 ± 0.32 logMAR and 0.53 ± 0.32 logMAR, respectively, and the difference of 0.01 ± 0.07 logMAR was not statistically significant (p = 0.51, t = 2.09). At least 80% of the IVAD measure of refraction components (M, J0, J45) were within ±0.50 D of SR measure.: IVAD is a practical and valid refraction method for low vision patients.
Topics: Aged; Aged, 80 and over; Humans; Middle Aged; Refraction, Ocular; Reproducibility of Results; Vision Tests; Vision, Low; Visual Acuity
PubMed: 33689633
DOI: 10.1080/08164622.2021.1878825 -
International Ophthalmology Sep 2020To describe visual performance in high myopia.
PURPOSE
To describe visual performance in high myopia.
METHODS
In this cross-sectional study, 148 emmetropes [spherical equivalent (SE) - 0.50 to + 1.00 D] and 564 high myopes [SE ≤ - 6.00 D] were categorised into three groups (Group 1: SE - 6.00 to > - 8.00 D; Group 2: SE - 8.00 to > - 10.00 D; and Group 3: SE ≤ - 10.00 D). Multivariate regression analyses adjusting for age and ethnicity examined the relationship between corrected distance visual acuity (CDVA) [photopic, mesopic and super vision test-night vision goggles (SVT-NVG)] and contrast sensitivity (CS)] (mesopic and SVT-NVG) with SE and axial length (AL).
RESULTS
Mean age of subjects was 21.07 ± 1.17 years, and majority were Chinese (91.9%). Mean SE was 0.10 ± 0.23 D (emmetropes) and - 8.76 ± 2.04 D (high myopes), p < 0.001. Higher degrees of myopia were associated with reduced CDVA and CS, and increased AL (all p < 0.001). Among high myopes, Group 1 had the highest proportion of subjects with good CDVA (photopic ≤ 0.00 LogMAR, mesopic ≤ 0.00 LogMAR and NVG ≤ 0.10 LogMAR) and CS (mesopic ≥ 0.75 LogCS and NVG ≥ 0.35 LogCS) compared with Groups 2 and 3 (all p < 0.001). Among high myopes with good VA (photopic ≤ 0.00 LogMAR, mesopic ≤ 0.00 LogMAR and NVG ≤ 0.10 LogMAR), Group 1 also had the highest proportion of subjects who achieved mesopic ≥ 0.75 LogCS and NVG ≥ 0.35 LogCS (both p < 0.001). Multivariate analyses demonstrated that reduced VA and CS were associated with decreased SE and increased AL (all p < 0.001).
CONCLUSIONS
High myopia is associated with reduced VA and reduced CS.
Topics: Adult; Contrast Sensitivity; Cross-Sectional Studies; Humans; Myopia; Refraction, Ocular; Vision Tests; Visual Acuity; Young Adult
PubMed: 32385613
DOI: 10.1007/s10792-020-01403-7 -
Clinical & Experimental Optometry Apr 2023The clinical assessment of distance stereoacuity is important in some ocular conditions. Given the different neurophysiological mechanism for crossed and uncrossed...
CLINICAL RELEVANCE
The clinical assessment of distance stereoacuity is important in some ocular conditions. Given the different neurophysiological mechanism for crossed and uncrossed stereoacuities, evaluation of both may provide additional insight into binocular vision disorders.
BACKGROUND
Clinical devices measuring distance crossed and uncrossed stereopsis are not readily available. Visotec Distance Stereo Test (VDST) is a contour-based device designed to measure both forms of distance stereoacuity. This study assesses the validity and test-retest reliability of the device in comparison to the random dot-based Randot Distance Stereo Test (RDST).
METHOD
VDST and RDST were administered to a total of 107 children, that included 51 'normal' and 56 'abnormal' (37 intermittent exotropia and 19 amblyopia) between the ages of 5 and 15 years. Two examiners retested stereoacuities in a sub-set of 62 randomly selected subjects. Stereoacuity was transformed to log scale. 95% limits of agreement were calculated for test-retest reliability. The Bland-Altman plot was used to demonstrate the agreement between the tests and the examiners.
RESULTS
The mean ± SD crossed distance stereoacuities using VDST in normal, intermittent exotropia and amblyopic children were 93.1 ± 43.8, 161.9 ± 89.8 and 236.3 ± 122.4 arcseconds, respectively. For uncrossed stereoacuity, these were 104.7 ± 54.0, 187.6 ± 89.6 and 265.5 ± 144.0 arcseconds, respectively. Crossed stereoacuity was significantly better than uncrossed stereoacuity. 95% limits of test-retest agreement for crossed and uncrossed stereoacuities using the VDST were 0.27 and 0.30, respectively. An exact test-retest match using VDST was 84% in normals and 77% in abnormals for crossed and 83% in normal and 74% in abnormal for uncrossed stereoacuities.
CONCLUSION
VDST is a reliable, valid and easy-to-administer distance crossed and uncrossed stereoacuity measuring device. Further studies are required to establish the clinical importance of assessing these two forms stereoacuities in relation to various binocular vision disorders.
Topics: Child; Humans; Child, Preschool; Adolescent; Vision Tests; Exotropia; Reproducibility of Results; Visual Acuity; Depth Perception; Amblyopia; Vision Disorders; Vision, Binocular
PubMed: 35125046
DOI: 10.1080/08164622.2022.2033599 -
Ophthalmic & Physiological Optics : the... Jan 2022Current chart-based tests of spatial contrast sensitivity (SCS) with fixed or narrow frequency ranges (≤18 cycles/°) cannot characterise the limits of spatial...
PURPOSE
Current chart-based tests of spatial contrast sensitivity (SCS) with fixed or narrow frequency ranges (≤18 cycles/°) cannot characterise the limits of spatial contrast vision. Here we present the design and validation of a chart-based measure of the spatial contrast envelope.
METHODS
Following the principles of the standard visual acuity (Bailey-Lovie) and contrast sensitivity (Pelli-Robson) charts, a combined spatial-contrast and visual acuity chart was designed using a language-independent triangular symbol for a four-alternative forced-choice procedure plus chart rotation. Symbol frequencies ranged between 0.38 and 60 cycles/° spaced along 10 radial axes (0.55%-100% contrast). The chart was validated with reference to the Bailey-Lovie and Pelli-Robson charts; its reliability and sensitivity to changes in illumination, simulated cataract and blur was evaluated in healthy adults.
RESULTS
The photopic SCS function could be measured in 5.5 ± 0.5 min; thresholding around the spatial contrast resolution limit reduced completion times to ~2 min. There was good agreement with high-contrast visual acuity (difference = 0.08 ± 0.02 logMAR) and contrast-sensitivity at 1.5 cycles/° (0.13 ± 0.06 logCS). Test-retest reliability was excellent at all spatial frequencies (ICC = 0.99). Mesopic illumination or simulated cataract caused a generalised SCS loss; myopic blur reduced high-frequency sensitivity. Spatial contrast sensitivity was independent of radial axis orientation (cardinal or oblique).
CONCLUSIONS
The chart provides a time-efficient, reliable and inexpensive measure of SCS with applications in research and clinic for detecting subtle deficits in early stages of ocular and neurological conditions that often manifest at higher frequencies. It is sensitive to vision changes occurring in dim lighting and with simulated cataract and blur. The chart is available open-access for self-printing; contrast variation in print can be controlled through user calibration and/or establishing normative SCS functions using the theoretical values.
Topics: Adult; Color Vision; Contrast Sensitivity; Humans; Reproducibility of Results; Vision Tests; Visual Acuity
PubMed: 34755353
DOI: 10.1111/opo.12914 -
Translational Vision Science &... Dec 2020Visual prostheses aim to restore, at least to some extent, vision that leads to the type of perception available for sighted patients. Their effectiveness is almost...
UNLABELLED
Visual prostheses aim to restore, at least to some extent, vision that leads to the type of perception available for sighted patients. Their effectiveness is almost always evaluated using clinical tests of vision. Clinical vision tests are designed to measure the limits of parameters of a functioning visual system. I argue here that these tests are rarely suited to determine the ability of prosthetic devices and other therapies to restore vision. This paper describes and explains many limitations of these evaluations. Prosthetic vision testing often makes use of multiple-alternative forced-choice (MAFC) procedures. Although these paradigms are suitable for many studies, they are frequently problematic in vision restoration evaluation. Two main types of problems are identified: (1) where nuisance variables provide spurious cues that can be learned in repeated training, which is common in prosthetic vision, and thus defeat the purpose of the test; and (2) even though a test is properly designed and performed, it may not actually measure what the researchers believe, and thus the interpretation of results is wrong. Examples for both types of problems are presented. Additional problems arise from confounding factors in the administration of tests are pointed as limitations of current device evaluation. For example, head tracing of magnified objects enlarged to compensate for the system's low resolution, in distinction from the scanning head (camera) movements with which users of prosthetic devices expand the limited field of view. Because of these problems, the ability to perform satisfactorily on the clinical tests is necessary but insufficient to prove vision restoration, therefore, additional tests are needed. I propose some directions to pursue in such testing.
TRANSLATIONAL RELEVANCE
Numerous prosthetic devices are being developed and introduced to the market. Proving the utility of these devices is crucial for regulatory and even for post market acceptance, which so far has largely failed, in my opinion. Potential reasons for the failures despite success in regulatory testing and directions for designing improved testing are provided. It is hoped that improved testing will guide improved designs of future prosthetic systems and other vision restoration approaches.
Topics: Humans; Movement; Vision Tests; Vision, Ocular; Visual Prosthesis
PubMed: 33384886
DOI: 10.1167/tvst.9.13.32 -
Journal of Vestibular Research :... 2021Clinical vestibular technology is rapidly evolving to improve objective assessments of vestibular function. Understanding the reliability and expected score ranges of...
BACKGROUND
Clinical vestibular technology is rapidly evolving to improve objective assessments of vestibular function. Understanding the reliability and expected score ranges of emerging clinical vestibular tools is important to gauge how these tools should be used as clinical endpoints.
OBJECTIVE
The objective of this study was to evaluate inter-rater and test-retest reliability intraclass correlation coefficients (ICCs) of four vestibular tools and to determine expected ranges of scores through smallest real difference (SRD) measures.
METHODS
Sixty healthy graduate students completed two 1-hour sessions, at most a week apart, consisting of two video head-impulse tests (vHIT), computerized dynamic visual acuity (cDVA) tests, and a smartphone-assisted bucket test (SA-SVV). Thirty students were tested by different testers at each session (inter-rater) and 30 by the same tester (test-retest). ICCs and SRDs were calculated for both conditions.
RESULTS
Most measures fell within the moderate ICC range (0.50-0.75). ICCs were higher for cDVA in the inter-rater subgroup and higher for vHITs in the test-retest subgroup.
CONCLUSIONS
Measures from the four tools evaluated were moderately reliable. There may be a tester effect on reliabilities, specifically vHITs. Further research should repeat these analyses in a patient population and explore methodological differences between vHIT systems.
Topics: Head Impulse Test; Humans; Reproducibility of Results; Vestibule, Labyrinth; Vision Tests; Visual Acuity
PubMed: 33646190
DOI: 10.3233/VES-201522 -
JAMA Ophthalmology Mar 2021Many ophthalmology appointments have been converted to telemedicine assessments. The use of a printed vision chart for ophthalmology telemedicine appointments that can...
IMPORTANCE
Many ophthalmology appointments have been converted to telemedicine assessments. The use of a printed vision chart for ophthalmology telemedicine appointments that can be used by people who are excluded from digital testing has yet to be validated.
OBJECTIVES
To evaluate the repeatability of visual acuity measured using the Home Acuity Test (HAT) and the agreement between the HAT and the last in-clinic visual acuity.
DESIGN, SETTING, AND PARTICIPANTS
This diagnostic study was conducted from May 11 to 22, 2020, among 50 control participants and 100 adult ophthalmology outpatients who reported subjectively stable vision and were attending routine telemedicine clinics. Bland-Altman analysis of corrected visual acuity measured with the HAT was compared with the last measured in-clinic visual acuity on a conventional Early Treatment Diabetic Retinopathy Study logMAR chart.
MAIN OUTCOMES AND MEASURES
For control participants, repeatability of the HAT and agreement with standard logMAR visual acuity measurement. For ophthalmology outpatients, agreement with the last recorded in-clinic visual acuity and with the International Classification of Diseases and Related Health Problems, 11th Revision visual impairment category.
RESULTS
A total of 50 control participants (33 [66%] women; mean [SD] age, 36.0 [10.8] years) and 100 ophthalmology patients with a wide range of diseases (65 [65%] women; mean [SD] age, 55.3 [22.2] years) were recruited. For control participants, mean (SD) test-retest difference in the HAT line score was -0.012 (0.06) logMAR, with limits of agreement (LOA) between -0.13 and 0.10 logMAR. The mean (SD) difference in visual acuity compared with conventional vision charts was -0.14 (0.14) logMAR (range, -0.4 to 0.18 log MAR) (-7 letters) in controls, with LOA of -0.41 to 0.12 logMAR (-20 to 6 letters). For ophthalmology outpatients, the mean (SD) difference in visual acuity was -0.10 (0.17) logMAR (range, -0.5 to 0.3 logMAR) (1 line on a conventional logMAR sight chart), with the HAT indicating poorer visual acuity than the previous in-clinic test, and LOA of -0.44 to 0.23 logMAR (-22 to 12 letters). There was good agreement in the visual impairment category for ophthalmology outpatients (Cohen κ = 0.77 [95% CI, 0.74-0.81]) and control participants (Cohen κ = 0.88 [95% CI, 0.88-0.88]).
CONCLUSIONS AND RELEVANCE
This study suggests that the HAT can be used to measure visual acuity by telephone for a wide range of ophthalmology outpatients with diverse conditions. Test-retest repeatability is relatively high, and agreement in the visual impairment category is good for this sample, supporting the use of printed charts in this context.
Topics: Adult; Female; Humans; Male; Middle Aged; Outpatients; Printing; Reproducibility of Results; Telemedicine; Vision Disorders; Vision Screening; Vision Tests; Young Adult
PubMed: 33410910
DOI: 10.1001/jamaophthalmol.2020.5972 -
Korean Journal of Ophthalmology : KJO Oct 2020To determine whether contrast sensitivity (CS) can represent photophobia in intermittent exotropia (IXT) by comparing the CS test with and without glare stimulus, and to...
PURPOSE
To determine whether contrast sensitivity (CS) can represent photophobia in intermittent exotropia (IXT) by comparing the CS test with and without glare stimulus, and to analyze the factors of IXT affecting CS.
METHODS
We retrospectively reviewed the medical records of 107 patients with basic-type IXT. We compared CS under mesopic and photopic conditions, with and without glare. We compared the difference in CS before and after glare (ΔCS) between mesopic and photopic conditions, and compared CS with glare between patients with and without photophobia. The correlations between the clinical features of IXT and CS were analyzed.
RESULTS
There was no significant reduction in CS at all spatial frequencies by glare stimulus. ΔCS was greater at high spatial frequencies under photopic conditions than under mesopic conditions. The group with subjective photophobia showed lower CS at 10.2 cpd under mesopic conditions with glare. CS showed a negative correlation with stereopsis under both mesopic and photopic conditions, and a positive correlation with fusional ability at low and intermediate spatial frequencies under mesopic conditions. ΔCS was smaller at intermediate spatial frequencies with better fusional ability, greater at high spatial frequencies with photophobia, and greater at intermediate spatial frequencies with a higher frequency of exotropia.
CONCLUSIONS
The CS test could not represent photophobia in IXT. However, CS tended to decrease with glare stimulus, and CS under mesopic conditions with glare was worse when accompanied by photophobia. Moreover, a poorer degree of stereopsis was associated with lower CS, and better fusional ability was associated with higher CS under mesopic conditions. Therefore, the CS test can be considered helpful in evaluating sensory function in IXT.
Topics: Adolescent; Child; Child, Preschool; Contrast Sensitivity; Exotropia; Female; Follow-Up Studies; Humans; Male; Retrospective Studies; Vision Tests; Visual Acuity; Young Adult
PubMed: 33099561
DOI: 10.3341/kjo.2020.0058 -
PloS One 2022We investigated the effect of luminance on refraction and visual function under twilight conditions.
PURPOSE
We investigated the effect of luminance on refraction and visual function under twilight conditions.
METHODS
Twenty young adults (mean age 20.5 ± 0.5 years) without ocular diseases and 20 eyes were included in the study. Subjective and objective spherical equivalent power (SE), logMAR, pupil diameter, ocular aberration, and ocular axial length were evaluated. Measurements were conducted in a light room with high luminance (300 cd/m2) targets (photopic), in a dark room with low luminance (10 cd/m2) targets (twilight), and a dark room after 15 min of adaptation to low luminance (10 cd/m2) targets (after adaptation: AA). Differences between the three conditions were analyzed using the Friedman test and Scheffe's multiple comparisons.
RESULTS
The results of logMAR were -0.20 ± 0.07, -0.08 ± 0.08, and -0.11 ± 0.08 in photopic, twilight, and AA, respectively, with significant differences between photopic and twilight (p < 0.001) and between photopic and AA (p < 0.001). Then subjective SE were -3.58 ± 2.04 D, -3.75 ± 2.08 D, and -3.74 ± 2.04 D in photopic, twilight, and AA, respectively, with significant differences between photopic and twilight (p = 0.007) and photopic and AA (p = 0.023). However, none of the other objective SEs produced a significant difference (p = 0.63). The pupil diameter and ocular aberration changed significantly in all conditions (p < 0.001).
CONCLUSIONS
Subjective myopic refraction increased and visual resolution decreased in younger subjects. However, this change in refraction is less than one level (±0.25 D) in clinical optometry, so fully corrected eyeglasses are important when assuming refraction in twilight, and there is no need for additional correction.
Topics: Adult; Color Vision; Eyeglasses; Humans; Myopia; Refraction, Ocular; Vision Tests; Young Adult
PubMed: 35427398
DOI: 10.1371/journal.pone.0267149 -
Eye (London, England) Jun 2023Keratoconus is associated with thinning and anterior protrusion of the cornea resulting in the symptoms of blurry and distorted vision. The commonly used clinical vision...
BACKGROUND
Keratoconus is associated with thinning and anterior protrusion of the cornea resulting in the symptoms of blurry and distorted vision. The commonly used clinical vision tests such as visual acuity and contrast sensitivity may not reflect the symptoms experienced in keratoconus and there are no quantitative tools to measure visual distortion. In this study, we used a quantitative test based on vernier alignment and field matching techniques to quantify visual distortion in keratoconus and assess its relation to corneal structural changes.
METHODS
A total of 50 participants (25 keratoconus and 25 visually normal) completed the experiment where they aligned supra-threshold white target circles in opposite field in reference to guidelines and circles to complete a square structure monocularly. The task was repeated five times and the global distortion index (GDI) and global uncertainty index (GUI) were calculated as the mean and standard deviation respectively of local perceived misalignment of target circles over five trials.
RESULTS
Both GDI and GUI were higher in participants with keratoconus compared to controls (p < 0.01). Both parameters correlated with the best corrected visual acuity, maximum corneal curvature (K), topographical keratoconus classification (TKC) and central corneal thickness (CCT).
CONCLUSION
Our findings show that the quantitative measure of distortion could be a useful tool for behavioural assessment of progressive keratoconus.
Topics: Humans; Keratoconus; Corneal Topography; Cornea; Visual Acuity; Vision, Ocular
PubMed: 36104521
DOI: 10.1038/s41433-022-02240-x