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. 2018 Jan 30;8(1):1919.
doi: 10.1038/s41598-018-20344-x.

Individual neural transfer function affects the prediction of subjective depth of focus

Alexander Leube  1 , Tim Schilling  2 , Arne Ohlendorf  2   3 , David Kern  3 , Alex G Ochakovski  4 , M Dominik Fischer  2   4   5 , Siegfried Wahl  2   3
Affiliations

Individual neural transfer function affects the prediction of subjective depth of focus

Alexander Leube et al. Sci Rep. .

Abstract

Attempts to accurately predict the depth of focus (DoF) based on objective metrics have failed so far. We investigated the effect of the individual neural transfer function (iNTF) on the quality of the prediction of the subjective DoF from objective wavefront measures. Subjective DoF was assessed in 22 participants using subjective through focus curves of visual acuity (VA). Objective defocus curves were calculated for visual Strehl metrics of the optical (VSOTFa) and the modulation transfer function as well as the point spread function. DoF was computed for residual lower order aberrations (rLoA) and incorporation of iNTF. Correlations between subjective and objective DoF did not reach significance, when a) standard metrics were used and b) rLoA were considered (r max = 0.33, p all > 0.05). By incorporating the iNTF of the individuals in the calculation of the objective DoF from the VSOTFa metric, a moderate statistically significant correlation was found (r = 0.43, p < 0.01, Pearson). The iNTF of the individual's eye is fundamental for the prediction of subjective DoF using the VSOTFa metric. Individualized predictions could aid future application in the correction of refractive errors like presbyopia using intraocular lenses.

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Conflict of interest statement

This work was done in an industry-on-campus-cooperation between the University Tuebingen and Carl Zeiss Vision International. GmbH. The work was supported by third-party-funding (ZUK 63) as part of the German Excellence initiative from the Federal Ministry of Education and Research (BMBF). A. Ohlendorf and S. Wahl are employees of Carl Zeiss. Vision International GmbH. A.Leube, D. Kern, A. Ochakovski and D. Fischer declare no potential conflict of interest.

Figures

Figure 1
Figure 1
Comparison of defocus curves calculated without lower order aberrations (LoA) and with residual LoAs for a sample participant.
Figure 2
Figure 2
(a) Relationship between contrast sensitivity function (CSF) and modulation transfer function (MTF). Data was fitted with a double exponential square root function (Equation 1) and represents the model of the neural transfer function (NTF). (b) Comparison of mean neural transfer function from the study group (n = 22) ±SD and the NTF adapted from Campbell & Green.
Figure 3
Figure 3
Individual differences between subjective and objective DoF (D) for through focus analysis using the C&G NTF and the individual NTF. Smaller prediction errors are indicated with ✓, whereas no change is shown with ° and higher errors are indicated by X.
Figure 4
Figure 4
Workflow for calculation of through focus curve from wavefront errors using image quality metrics. The parameters A and B describe the residual low order aberrations (LoA) and the individual neural transfer function, respectively, that are evaluated regarding the DoF prediction. Dia = Pupil diameter.
See this image and copyright information in PMC

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