scholarly journals Extracting Modulation Transfer Function of the Visual System from Contrast Sensitivity Function in External Noise

2013 ◽  
Vol 13 (9) ◽  
pp. 1268-1268 ◽  
Author(s):  
Z.-L. Lu ◽  
F. Hou ◽  
C.-B. Huang
Keyword(s):  
Transfer Function ◽  
Visual System ◽  
Contrast Sensitivity ◽  
Modulation Transfer Function ◽  
External Noise ◽  
Sensitivity Function ◽  
Contrast Sensitivity Function ◽  
Modulation Transfer

scholarly journals Comparison of visual and optical quality of monofocal versus multifocal intraocular lenses

2019 ◽  
Vol 30 (2) ◽  
pp. 299-306 ◽  
Author(s):  
Irene Altemir-Gomez ◽  
Maria S Millan ◽  
Fidel Vega ◽  
Francisco Bartol-Puyal ◽  
Galadriel Gimenez-Calvo ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Transfer Function ◽  
Contrast Sensitivity ◽  
Intraocular Lens ◽  
Modulation Transfer Function ◽  
Area Under The Curve ◽  
Optical Quality ◽  
Intraocular Lenses ◽  
Modulation Transfer ◽  
Multifocal Intraocular Lenses

Objective: To compare visual quality in patients implanted with Tecnis® monofocal (ZCB00) and multifocal (ZMB00) intraocular lenses taking into account their optical quality measured in vitro with an eye model. Methods: In total, 122 patients participated in this study: 44 implanted with monofocal and 78 with multifocal intraocular lenses. Measurements of visual acuity and contrast sensitivity were performed. The optical quality of the intraocular lenses was evaluated in three image planes (distance, intermediate and near) using an eye model on a test bench. The metric considered was the area under the curve of the modulation transfer function. Results: Optical quality at the far focus of the monofocal intraocular lens (area under the curve of the modulation transfer function = 66.97) was considerably better than that with the multifocal lens (area under the curve of the modulation transfer function = 32.54). However, no significant differences were observed between groups at the distance-corrected visual acuity. Distance-corrected near vision was better in the multifocal (0.15 ± 0.20 logMAR) than that in the monofocal group (0.43 ± 0.21 logMAR, p < 0.001), which correlated with the better optical quality at near reached by the multifocal intraocular lens (area under the curve of the modulation transfer function = 29.11) in comparison with the monofocal intraocular lens (area under the curve of the modulation transfer function = 5.0). In intermediate vision, visual acuity was 0.28 ± 0.16 logMAR (multifocal) and 0.36 ± 0.14 logMAR (monofocal) with p = 0.014, also in good agreement with the values measured in the optical quality (area under the curve of the modulation transfer function = 10.69 (multifocal) and 8.86 (monofocal)). The contrast sensitivity was similar in almost all frequencies. Pelli–Robson was slightly better in the monofocal (1.73) than in the multifocal group (1.64; p = 0.023). Conclusion: Patients implanted with multifocal ZMB00 achieved a distance visual acuity similar to those implanted with monofocal ZCB00, but showed significantly better intermediate and near visual acuity. A correlation was found between intraocular lenses’ optical quality and patients’ visual acuity. Contrast sensitivity was very similar between the multifocal and monofocal groups.

Masking by Uniform Field Flicker: Some Practical Problems

Perception ◽  
1987 ◽  
Vol 16 (5) ◽  
pp. 641-647 ◽  
Author(s):  
David R Badcock ◽  
Elizabeth Sevdalis
Keyword(s):  
Visual System ◽  
Contrast Sensitivity ◽  
Human Visual System ◽  
Sensitivity Function ◽  
Relative Performance ◽  
Contrast Sensitivity Function ◽  
Uniform Field ◽  
Spatial Frequencies ◽  
The Mean ◽  
Mean Luminance

The technique of uniform field flicker (UFF) masking has frequently been used to address issues concerning the relative performance of sustained and transient neural channels in the human visual system. Unfortunately there has been an artifact in the implementation of this method in most published experiments which has meant that the contrast of the target has been flickered in synchrony with the mean luminance. A study is reported in which the artifact was corrected and the effects of UFF masking on the contrast sensitivity function then examined. With this correction, masking was still restricted to low spatial frequencies but it was much weaker than reported originally. It is argued that the original evidence suggesting that UFF masking can be used to examine the functioning of transient and sustained channels has not been interpreted correctly and that the basis for such a claim is weak.

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