Use of diffusing filters for artificially reducing visual acuity when testing equipment and procedures

Heinrich, Sven; Strübin, Isabell

doi:10.1007/s10633-019-09715-5

Cited by 10 publications

(5 citation statements)

References 31 publications

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“…Lehsing et al 87 also used the 0.1 Bangerter occlusion filter but were only able to achieve 0.40 LogMAR visual acuity. This discrepancy between the expected level and the actual level of visual impairment induced with a 0.1 Bangerter filter is consistent with the findings of Heinrich and Strubin, 104 who concluded that the Bangerter nominal grade did not match the actual effect on visual acuity. To achieve a particular level of visual impairment, other researchers used plus lenses, progressively adding power until the desired level of visual impairment was achieved.…”

Section: Variabilit Y In Expec Ted and Ac Tual Levels Of Simul Ation ...supporting

confidence: 87%

Simulation of visual impairment in persons with normal vision for scientific research

Abraham,

Sakyi‐Badu,

Boadi‐Kusi

et al. 2024

Ophthalmic Physiologic Optic

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Simulation of visual impairment in healthy eyes has multiple applications in students' training, research and product development. However, due to the absence of an existing standard protocol, the method of simulation was left to the discretion of the researcher. This review aimed to outline the various methods of simulating visual impairment and categorising them. A scoping review of the relevant publications was conducted. Of the 1593 articles originally retrieved from the databases, 103 were included in the review. The characteristics of the participants, the method for simulation of the visual impairment in persons with normal vision and the level or type of visual impairment that was simulated were extracted from the papers. None of the methods of simulation can be judged as being superior to the others. However, electronic displays produced the most consistent form of visual impairment simulation.

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Section: Variabilit Y In Expec Ted and Ac Tual Levels Of Simul Ation ...supporting

confidence: 87%

Simulation of visual impairment in persons with normal vision for scientific research

Abraham,

Sakyi‐Badu,

Boadi‐Kusi

et al. 2024

Ophthalmic Physiologic Optic

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“…For degraded vision, we did not obtain behavioral acuity estimates in the present study as the focus of the study was a comparison between VEP-based estimates. However, we know from a previous study [ 40 ] that the filter used for degradation typically reduces acuity to a logMAR value of about 1.0, which is matched quite well by the acuity estimates obtained with the heuristic algorithm.…”

Section: Discussionsupporting

confidence: 74%

“…With this eye, VEP-based acuity estimates were obtained either with normal vision or with vision degraded by placing a diffusing filter (1° Light Shaping Diffuser, Luminit, Torrance, CA, USA) in a trial frame in front of the study eye. This filter produced Gaussian blur and reduced acuity to around 0.09 decimal acuity (logMAR = 1.06) as measured behaviorally in a recent study [ 40 ].…”

Section: Methodsmentioning

confidence: 99%

VEP-based acuity estimation: unaffected by translucency of contralateral occlusion

2021

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Purpose Visual evoked potential (VEP) recordings for objective visual acuity estimates are typically obtained monocularly with the contralateral eye occluded. Psychophysical studies suggest that the translucency of the occluder has only a minimal effect on the outcome of an acuity test. However, there is literature evidence for the VEP being susceptible to the type of occlusion. The present study assessed whether this has an impact on VEP-based estimates of visual acuity. Methods We obtained VEP-based acuity estimates with opaque, non-translucent occlusion of the contralateral eye, and with translucent occlusion that lets most of the light pass while abolishing the perception of any stimulus structure. The tested eye was measured with normal and artificially degraded vision, resulting in a total of 4 experimental conditions. Two different algorithms, a stepwise heuristic and a machine learning approach, were used to derive acuity from the VEP tuning curve. Results With normal vision, translucent occlusion resulted in slight, yet statistically significant better acuity estimates when analyzed with the heuristic algorithm (p = 0.014). The effect was small (mean ΔlogMAR = 0.06), not present in some participants, and without practical relevance. It was absent with the machine learning approach. With degraded vision, the difference was tiny and not statistically significant. Conclusion The type of occlusion for the contralateral eye does not substantially affect the outcome of VEP-based acuity estimation.

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“…The second experiment was performed with six healthy volunteers, aged between 20 and 43 years (mean 28.9 ± 8.7 SD), recruited from the staff of the Center for Ophthalmology at the University of Tuebingen (one volunteer also took part in the first study), according to the same criteria as for the first experiment. Visual acuities were determined using the Freiburg Visual Acuity & Contrast Test (FrACT) [ 10 , 11 ] for BCVA and two artificially reduced viewing conditions using Bangerter occlusion foils (0.6, 0.4) [ 12 ]. In both experiments, only one eye of each participant was assessed.…”

Section: Methodsmentioning

confidence: 99%

Comparison of CRT and LCD monitors for objective estimation of visual acuity using the sweep VEP

et al. 2022

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Purpose To investigate the applicability of liquid crystal displays (LCD) as suitable replacement for cathode ray tube monitors (CRT) as stimulator for the sweep VEP for estimating visual acuity. Methods In a first experiment, sweep VEPs were recorded in 13 healthy volunteers with best-corrected visual acuity with an LCD and a CRT monitor, respectively. Time-to-peak after stimulus and peak-to-trough amplitudes as well as the visual acuity, estimated using a second-order polynomial and the modified Ricker model, were compared between both monitor types. In a second experiment, sweep VEPs were recorded in six healthy volunteers with two levels of stimulus contrast using artificially reduced visual acuities as well as best-corrected with the same monitors as in the first experiment and additionally, a modern LCD gaming monitor with a response time of 1 ms. Time-to-peak after stimulus and peak-to-trough amplitudes were compared between the different combinations of monitors and contrasts. Finally, visual acuities estimated using the modified Ricker model were compared to subjective visual acuities determined using the Freiburg Visual Acuity and Contrast Test (FrACT). Results In the first experiment, the time-to-peak after stimulus presentation was statistically significantly delayed for LCD displays (mean difference [confidence interval]: 60.0 [54.0, 65.9] ms; t(516) = 19.7096, p < 0.0001). Likewise, peak-to-trough amplitudes were statistically significantly smaller for the LCD stimulator, however, not clinically relevant (mean difference [confidence interval]: − 0.89 [– 1.59, − 0.20] µV; t(516) = − 2.5351, p = 0.0115). No statistically significant effect of the monitor type on the estimated visual acuity was found for neither method, second-order polynomial, nor the modified Ricker model. In the second experiment, statistically significant delays of the time-to-peak after stimulus onset were found for all combinations of monitor and contrast compared to the CRT monitor. A statistically significant, but not clinically relevant, difference of the peak-to-trough amplitudes was only found between the CRT monitor and the LCD gaming monitor (mean difference [confidence interval]: 2.6 [1.2, 4.0] µV; t(814) = 4.66, p < 0.0001). Visual acuities estimated from LCD stimulation significantly underestimated the subjective visual acuity up to 0.2 logMAR using the conversion formula of the first experiment. No statistically significant difference was found when using conversion formulas adjusted for each combination of monitor and contrast. Conclusions Based on the results of this study, LCD monitors may substitute CRT monitors for presenting the stimuli for the sweep VEP to objectively estimate visual acuity. Nevertheless, it is advisable to perform a calibration and to collect normative data of healthy volunteers using best-corrected and artificially reduced visual acuity for establishing a conversion formula between sweep VEP outcome and the subjective visual acuity before replacing a CRT with an LCD stimulator.

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Use of diffusing filters for artificially reducing visual acuity when testing equipment and procedures

Cited by 10 publications

References 31 publications

Simulation of visual impairment in persons with normal vision for scientific research

Simulation of visual impairment in persons with normal vision for scientific research

VEP-based acuity estimation: unaffected by translucency of contralateral occlusion

Comparison of CRT and LCD monitors for objective estimation of visual acuity using the sweep VEP

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